Water Treatment and Management System For Greenhouse Farming

Water Treatment and Management

0. Abstract

This report covers the activities running on water and energy conservation in greenhouse farming. To achieve its purpose the paper involves a study of the watergy project (A project launched in Europe to allow water conservation in greenhouses). Further to that, the report studies other methods utilized globally for efficient greenhouse cultivation. The technologies used in these processes are then be compared to identify the most economical as well as productive. Water is a primary resource in farming and in this case, it becomes necessary to identify positive water management practices. Additionally, effective greenhouse cultivation can bolster food production even in arid areas, thus ensuring global food security.

Water Treatment and Management

Table of Contents

Water Treatment and Management 2

0. Abstract 2

1. Introduction 2

1.1 Overview of the Watergy Project 3

1.2 Research Objectives and Motivation 7

1.3 Research Report Outline 8

2. Literature Review 8

2.1 Watergy greenhouse in Spain 9

2.2 Watergy greenhouse in Germany 10

2.2.1 Watergy Project Summary 11

2.3 Systems with similar goals as the Watergy greenhouse 12

2.3.1 Metrolina Greenhouses’ Quest to Improve Water Quality 13

2.3.2 Lucas Greenhouses Closed Loop System 15

3 Watergy greenhouse control Methodology 18

4. Outline of the thesis 19

5. Water treatment and desalination system in Greenhouse Model 20

5.1 Watergy greenhouse 20

5.2 Watergy climate model 20

5.3 Parameter estimation and discussion 22

246. Optimal Adaptive Control in Greenhouse model for Watery.

246.1. Optimal controller

256.2. Parameter estimation

256.3. Greenhouse emulation

297. Discussions and result analysis for watergy in greenhouses

308 Conclusion and Recommendations

1. Introduction

Water has a vast number of uses, as a fact life would be impossible without water. Plants need water for the production of energy, which they then transfer to animals. Humans also need water for various biological services not forgetting physiological services and also cooking. Seeing this maximum necessity of water, any step towards conserving it is a goal towards protecting our planet and the lives in it. In farming, much water that is provided to plants ends up evaporating into thin air due to contact with the sun’s radiation. A common strategy that the horticulture industry is adopting worldwide is the use of greenhouses to reduce the amount of water lost to the atmosphere. Greenhouses comprise of a polythene structure held in place by a metallic frame in which plants grow. The polythene cover allows light into the structure but rejects water loss through evaporation. This structure enables minimum water loss while enabling plants to grow in an optimally wet environment. One practice that has come to improve how greenhouses work is the watergy management system. This report will analyze practices that farmers can embrace in order to ensure proper water management in a greenhouse; it will use the watergy system as a case study.

1.1 Overview of the Watergy Project

The European Community’s Vth Framework in its Energy, Environment and Reasonable Development program supports the Watergy project. It comprises of the advancement of a sticky air sun oriented authority framework that takes after the guideline of a shut two stage thermo syphon. A mix of dissipation and buildup permits to utilize sunlight based warm vitality in a substantially more effective way. The principle favorable position is not just the diminishment of expenses in space cooling and warming, however the likelihood of water purging, as the framework also supports recycling low quality water to acquire refined water. The decentralization of warmth and water supply opens the likelihood of local locations where nurseries nourished with low quality water (dim water and saline water) could be utilized to create refined water and also warmth and natural products. The undertaking examines the improvement of two models: one application for dry atmospheres in Southern Europe with an accentuation on water generation with regards to nursery agriculture, also, another for mild Central European atmosphere concentrated on warmth and water generation for feasible design.

The restricted water resources pose genuine difficulties for the real status of escalated nursery cultivation as an exceptionally productive technology of food generation in Mediterranean territories. The intensive plant generation framework utilizing nurseries was moved from Central to Southern Europe due to the expanding energy costs. The semi arid Mediterranean atmosphere takes into account an idea of passive greenhouse with extensively less extra vitality request (Stanhill, 1980). In any case, despite the fact that the nursery itself is a method for water conservation(contrasted and outside development, greenhouse cultivation requests a third less water utilization Stanghellini, et al 2003), the water shortage connected with areas where the nurseries are blossoming is a genuine impairment for the manageability of the real production framework.

Albeit advanced innovation proposes desalination as a hotspot for this developing interest of water, common advances are likewise unequivocally influenced by their expansive interest for essential energy. Another mechanical arrangement that is broadly talked about is warmth and water recuperation from greeenhouse air release or from within closed greenhouse with the guide of heat exchangers and warmth accumulation frameworks (Goto et al, 1996, 1997). Be that as it may, this arrangement faces with a few issues:

  1. The measure of energy required for the transport of hot air to a heat exchanger, requiring constrained ventilation;

  2. The decreased efficiency of the warmth exchange from air to water because of the little warmth limit of air;

  3. The undesirable shading made on the plants by the warmth exchangers, normally set in the hottest zone of the nursery, which is the rooftop zone; and

  4. The low temperature administration set up by plant resistance (often not no more than 35ºC).

The issue of sustainable engineering is a growing one, and governments and private associations are advancing energy efficient structures. Be that as it may, although solar based energy is gradually being introduced in the energy parity of the structures with the utilization of standard sun power collectors and even means for heat storage, the viewpoint of water supply and sanitization is still subject to centralization and reliant on a current system.

Project Watergy proposes another idea of a solar collector based on a damp air circuit fueled by thermal sun based energy (Buchholz et al, 2003). The collector is shaped by a greenhouse associated with a sun-based chimney, within which a cooling channel contains an air-to-water heat exchanger connected with a heat aggregator. The procedure begins with the warming of the air inside the greenhouse, which ascends to the solar-based tower by natural lightness. The evapotranspiration of the plants and soil is included to the air, which gets to be humid. Over the greenhouse, expelled from the plant region, the rising air is further warmed in a secondary sunlight based collector until it achieves the most extreme temperature at the highest point of the sun powered tower. In this auxiliary collector, keeping in mind the end goal to immerse the rising air while it is warming, a humidification framework goes about as an extra dissipation source. The point is to have extremely hot and humid air at the highest point of the sun based tower. Inside the tower, a feedback channel contains a warmth exchanger which cools the air. On the surface of the warmth exchanger, the cooling of the humid air causes condensation, discharging extra thermal energy and refined water. The frosty and dry air falls back to the greenhouse, where it is warmed and humidified beginning the cycle once more. The last component of the closed framework is a strong state fermentation device (Buchholz, 2003). Greenhouse plants and fermentation micro-organisms supply each other with oxygen and carbon dioxide. Besides, metabolic waste warmth can be added to the heat accumulation.

This idea has noteworthy advantages contrasted to standard solar collectors. On one hand, the humid air permits to store more thermal energy at a given temperature, in view of the utilization of inactive warmth notwithstanding the sensible heat. This higher energy density of humid air implies that the same measure of energy can be transported by much lower air volume stream, which can be managed by regular bouyancy. Then again, the evaporation and condensation processes expand the productivity of the warmth exchange. This takes into account the warmth exchanger to be smaller and made of less expensive materials (i.e., plastic). Likewise, the division between the gatherer (greenhouse) and the heat exchanger (set inside the sun based tower) takes into account more surface of both components and further cost lessening. Moreover, the evaporation also, condensation forms open the likelihood of water cleaning as a major aspect of the solar energy gathering framework.

The energy gathered in the heat exchanger is put away amid the stacking stage in the external heat aggregators. Amid the deloading stage, the heat is discharged in the warmth exchanger by the inversion of the dissemination. The framework permits a few potential outcomes relying upon the prerequisites. The heat accumulation should be possible in a day by day or a regular premise. In hotter climates, heat gathered amid the day can be discharged during the night, however, in temperate climates the substantial contrast between seasons proposes a late spring heat gathering for winter release. The project ponders two variants of the collector, created in two diverse models, one for Mediterranean atmosphere with day-night stacking cycles and another for Central European atmosphere with a regular stockpiling of heat.

1.2 Research Objectives and Motivation

The objective of the engineering project is to investigate the water treatment and management framework for Greenhouse Farming. So as to enhance the water-sparing and reusing in the enclosed greenhouse, the venture will examine the innovations of water-saving and wastewater management practices essential for the enclosed greenhouse cultivation. Additionally a celebrated nursery project named Watergy in Spain will be talked about as contextual analysis. In the report, the following points will be discussed;

  1. To identify the principle of water treatment system in greenhouse.

  2. To identify the history and background of water treatment system in agricultural industry

  3. To List the affect of the water treatment system for the environment, community, and further development.

  4. To analysis material and structure of water treatment system

  5. To identify the actual technologies of water treatment in greenhouse application and analysis the advance and disadvantage of different water treatment with authority resource or data.

  6. To indicate what should be further investigated and research how the project can be developed in the future.

1.3 Research Report Outline

This paper will look into how the watergy project has been utilized in Spain and Germany in an attempt to allow for sustainable agricultural production and water conservation. In extension, the paper will look into other similar systems applied in the world and deduce the technologies and mechanisms of the process. The report will then analyze how the utilized mechanisms can be enhanced for better results in future.

2. Literature Review

Water and wastewater treatment organizations are massive energy clients that work 24 hours a day. Truth be told, for some districts, water and wastewater treatment can represent as much as 30 to 40% of their energy utilization. Notwithstanding, water and wastewater treatment organizations have not generally been urged to address the energy efficiency of their businesses. This in mind, energy utilization in most water frameworks worldwide could be lessened by no less than 25% through financially savvy effectiveness activities. At the same time lessening water spills and enhancing administration rehearses in utilities can drastically expand the measure of water accessible to end clients, while yielding huge economic savings.

In 1997, the Alliance dispatched the Watergy project to address the connection between water and energy in civil water and wastewater treatment frameworks. From that point forward the Watergy program has planned and completed undertakings in more than 100 urban communities over the globe. Watergy members in developing nations have spared more than 20.8 million kWh of power and $5 million in working expenses, and the economic benefits keep on accumulating.

To understand the vitality effectiveness capability of the water and wastewater treatment area, and also to instruct vitality proficiency program designers and arrangement creators, the Alliance offers an arrangement of services that incorporate energy evaluations, training, outreach,and support with electric and gas utilities, financing system examination and policy investigation. These efforts provide water and wastewater treatment offices with the instruments and education to accomplish noteworthy water and vitality funds that can moderate rate increments and sidetrack city incomes toward other public services. The Watergy system comes in two prototypes which have been tested in two countries Spain and Germany.

2.1 Watergy greenhouse in Spain

The first model (PT1) is a solitary closed greenhouse with the primary spotlight on warm control and water creation (Buchholz et al 2004). It has been implicit in Almería (southeast of Spain), which is additionally the region with the most elevated grouping of greenhouses on the planet. Common greenhouses comprises of a nursery of around 200 m2, with a standard excited iron structure and polyethylene plastic spread. The solar oriented tower is 10 m high, secured by polycarbonate, what’s more, the warmth exchanger inside the cooling channel is made of polypropylene tubes. The optional collector is a straightforward plastic layer on top of the plant zone with a water sprinkling framework on it. Outside the nursery, the warmth storage comprises of three deposits of polyethylene, which contain an aggregate of around 15 m3 water, associated with the warmth exchanger. Both the warmth exchanger and the warmth storage are built in a measured route for testing diverse degrees of performance and limit of the framework. The fermentation gadget has not been coordinated in this model to maintain a strategic distance from further confusions, and the CO2 fundamental for plants is artificially supplied as in an ordinary commercial nursery. The model incorporates modern measurement frameworks (temperature, air dampness what’s more, the streams of water, air and CO 2) to give far reaching data about its physical conduct. Sensors and actuators associated with low level controllers initiate a model-based ideal control framework [Jochum et al n.d].

2.2 Watergy greenhouse in Germany

The second model (PT2) has been developed in the city of Berlin in Germany. The test stage is experiencing alteration of the framework. In this model, the Watergy idea is connected to building technology as a sunlight based collector and water treatment instrument. The greenhouse (40 m2 surface, metallic structure secured with ETFE transparent foil) is appended to a two story building (120 m2, 6 m high, wood welted development). On the rooftop, a secondary collector with a humidificacion framework helps the extra warming and immersion of the air before it comes to the heat exchanger. In this procedure, condensation happens on the surface of the warmth exchanger as in PT1. The energy gathered is utilized to load regular warmth stockpiling of around 35 m3 limit, with a 60 cm layer of cellulosic protection. The warmth put away amid the warm part of the year is utilized for building and nursery heat supply amid the chilly part of the year. In this model the cooling conduit is put inside the building, and the warmth exchanger acts like a building heat radiation unit amid the waste air from the building can be headed to the greenhouse for more productive space warming.

In spite of the fact that it depends on the known ideas of standard inactive house protection and sun based warming frameworks from regular warmth stockpiles, it is the first occasion when that a supposed sun powered humid air gatherer is utilized for thermal heat generation. Moreover, the warmth exchange from air to water as a storage medium can take the role of direct warming of water, saving the utilization of ordinary sun based collectors. Other than its capacity as a solar collector, the utilization of the nursery in urban zones is considered as a strategy for reusing residential dim water, creating clean water for human utilization and additionally natural products such as plants. The greenhouse is sustained with dark water, natural waste and indeed, even utilized air from the building, delivers refined water. From a compositional perspective, the framework proposes a few difficulties:

  1. The idea of right around zero energy input in the climatization;

  2. The decentralization of supply, both of clear water and warmth, and wastewater exhaust;

  3. The utilization of light materials in the working, as the warmth accumulator permits diminishing the warm mass of the building.

2.2.1 Watergy Project Summary

The Watergy project proposes two models for use of a novel humid air solar collector. The first is a closed greenhouse for sun based solar thermal energy collection, water reusing, water desalination and progressed agricultural use. It is now built in Estación Experimental de Cajamar in Almería (Spain), and working subsequent to the fall of 2004. The framework permits controlling the atmosphere inside the shut nursery and shutting the water cycle with the recuperation of all the evapotranspiration from the plants. This opens an exceptionally fascinating probability for feasible administration of water in serious cultivation, as the greenhouse inundated with dark water turns into a method for delivering of organic products as well as clear water. Then again, if dark water is let well enough alone for the framework, the nursery can decrease extraordinarily its water use with the reuse of the recuperated refined water.

The second model is developed in Berlin (Germany), and it is a building with a self-sufficient supply of warmth furthermore of clear water. In this case, the closed greenhouse is associated with the building and sanitizes its remaining dim water. Next to its fundamental capacity as solar oriented collector and water distiller, the greenhouse gives fruits and vegetables can be fed with leftover air from the building. The more effective gathering of sun based thermal energy in the framework and its occasional stockpiling take into consideration a passive climatization of the building. With regards to manageable engineering, the Watergy framework implies that this idea of zero energy is supplemented with that of water autarchy.

The Watergy project proposes the joining of greenhouses in urban territories in beneficial interaction with houses. The greenhouse is joined as a feature of a new humid air sun based collection framework in which the warmth accumulation process takes into consideration dark water filtration and edible biomass improvement. The framework produces water of higher quality than standard biological treatment strategies. The greenhouse is a piece of the collector surface, but however offers further points of interest as a supplementary living space and an incorporated food creation framework. The treatment of urban wastewater in such an independent and nearby way opens two potential outcomes of awesome enthusiasm for the economical man.

2.3 Systems with similar goals as the Watergy greenhouse

Water recycling is not a strange thought for greenhouse cultivators; numerous have done it for a long time. Be that as it may, a few producers are taking water recycling to another level with 5-micron channel innovation, ozonation and rainwater collecting. These strategies guarantee that the water these producers use is the cleanest, most pure water accessible, permitting them to decrease pesticide and fungicide use, enhance plant wellbeing and acknowledge cost savings. What’s more, they’re additionally demonstrating that because of water catchment frameworks, it’s conceivable to be totally independent of city and ground water.

2.3.1 Metrolina Greenhouses’ Quest to Improve Water Quality

According to Abe Van Wingerden of Metrolina Greenhouses in Huntersville, N.C. Clean water is their number one chemical «Numerous producers miss that. They test their water quality and use chemicals to alleviate those issues. We do the inverse to decrease synthetic use.» For sure, the Van Wingerdens have been on a mission to enhance their water quality in the course of recent years. They achieve this with a unique combination of collecting rain water, recovering utilized irrigation water and usage of two sifting frameworks including 5-micron innovation, they have utilized critical time and money to furnish crops with the most pure water.

Metrolina has been gathering, reusing and testing water for over 30 years. They constructed the operation’s first retention pond in 1976, and today, Metrolina has three ponds on its property that can hold up to 250 million gallons of water. The 162-acre of greenhouse organization gets 98 percent of its water from the ponds, which store collected rain water only. Metrolina has never utilized city water and just uses well water in a couple of particular cases, depending on rainfall to supply the more than 1.5 million gallons of water it utilizes day by day.

As indicated by Director of Research Mark Yelanich, Metrolina’s rainwater catchment framework yields 5 million gallons of water from one inch of downpour. Water is gathered from stores rooftops, greenhouse rooftops, surge floors, the adjoining parking garage, which is built with pervious cement, and drains in the yard. All collected water channels through a progression of interfacing funnels to the maintenance lakes. From that point, it is separated through a complicated framework and cleaned before it touches the plants. In 2010, the Van Wingerdens became disappointed with their water quality and chose to glance around at other greenhouse operations to fix the problem. They met Charlie Hayes, an agrarian water master with Advanced Treatment Technologies, who broke down Metrolina’s water source, maintenance ponds, filtration frameworks, nursery drainage floor frameworks and water sanitizing process.

Consequently, the Van Wingerdens actualized the up and coming era of filtering innovation, introducing Dramm 5-micron channel frameworks in two of its nursery ranges. Water from the maintenance lakes now channels through a 50-micron channel to catch huge particles and residue. From that point, it experiences the 5-micron channels, which remove malady pathogens like Phytophthora, Pythium and Rhizoctonia from entering the water supply. Next, the water is purified through a copper ionization process and pumped into one of three holding tanks, measuring 600,000 gallons, 500,000 gallons and 300,000 gallons. Water for the irrigation system blasts is pumped straight ahead from the holding tank to the plants, while the flooding irrigation water goes through the manure nourish before being pumped into the nursery to surge floors. It takes 30 to 40 minutes to the surge floors, utilizing somewhere around 30,000 and 40,000 gallons for every inlet. It requires an equivalent measure of time for unused water to return and refilter into the 600,000 gallon tank, where the water bolster level is checked and quality is tried. In the event that the water is excessively messy, making it impossible to be reused, it does a reversal to the maintenance lake and through the filtering procedure (Drotleff, 2012).

2.3.2 Lucas Greenhouses Closed Loop System

During the time George and Louise Lucas began Lucas Greenhouses in Monroeville, N.J., their water concerns were engaged fundamentally on having an adequate supply of irrigation water. Farming was generally straightforward in 1979. They cultivated in polythene secured houses that had soil floors. The water used for irrigation was absorbed into the soil without creating a fuzz. George comments that they needed their operations to be eco-friendly, however the equipment and the demands to accomplish more were essentially not available. Like most cultivators working around then, edges were better ready to ingest some leakages coming about because of irrigating system issues and water quality issues. There wasn’t a great deal of worry about water confinements and preservation.

After a period of 32 years, Lucas Greenhouses is completing the establishment of a standout project amongst the most modern closed system water protection and treatment frameworks in the U.S. giant farming industry. There were a few explanations behind concentrating on water protection, including a feeling of municipal obligation; worries about plant security; ecological issues and the budgetary viewpoint. Water administration challenges, including having a satisfactory water supply, sifting vast volumes of water, automating manure infusion, avoiding pathogen sullying and constraining water and chemical spillover, had dependably been tended to as they emerged. Tending to these difficulties, the Lucases turned out to be more mindful of the requirements for better water administration and their arrangements to address them turned out to be more aggressive.

The beginning strides toward water preservation and spillover control truly started at Lucas in the 1970s with the burrowing of an overflow maintenance pond. The pond, which was then enlarged by three times, is committed to catching the majority of the downpour spillover from the greenhouse rooftops. The pond, which has an area of around 150,000 square feet, holds around 13.5 million gallons of water. Being fed by regular springs, the pond is a key part of the organization’s independent, zero spillover water administration framework. As they constructed more greenhouses, Lucas increased his water conservation endeavors. In 2002, The farm introduced their first drainage floor system incorporated with an Argus PC control framework. The introduction of this computer saw the automation of the irrigation process, it became a flagship model that would collect and reuse water automatically. The flood floors significantly decreased the measure of water utilized and the quantity of spillover. The PC controls enhanced water preservation by settling on more exact choices about when to irrigate the farm. the company expanded this project in 2004, 2007 and 2008. The total land under cultivation is 770,000 square feet.

Amid this time of extension the organization attempted different chemicals to sterilize the irrigation system water, however it observed them to be too exorbitant and/or tedious to utilize. Lucas discovered that appropriate checking of water treatment inputs and results is tedious yet mandatory to keep up sensible pathogen kill levels with synthetic arrangements. The organization additionally attempted a UV light refinement framework, yet never finished the establishment. The framework’s measurements were wrongly estimated for the measure of water that should have been dealt with. Soon after the last nursery development in 2008, the organization shifted its regard for the overflow that was leaving its property, especially the release from gathering reservoirs. The organization was searching for an approach to expel any hints of pesticides, herbicides and plant development controllers that would be present in the water spillover.

During a Water Education forum in Florida, organization authorities found out about ozone treatment. They were acquainted with the biochemical procedure of cutting edge oxidation, which consolidates ozone with either hydrogen peroxide mixes or bright light. This treatment strategy can be utilized to wipe out water-borne pathogens and in addition numerous chemicals, including the herbicide glyphosate. Taking crucial lessons from the forum, the organization introduced the ozone technology in the farm, which was vital for water sanitization. Water is re-circled from three surge tanks through a pre-treatment filtration framework that evacuates around 95 percent of the particulates down to 5 microns (the total microscopic size is 20 microns). The water is then flowed through a protected ozone reaching framework, where it is sterilized utilizing ozone gas and afterward come back to the tank from which it came. The framework is intended to work 24 hours a day, pivoting from tank to tank. The framework was additionally observed to be compelling against water-borne pathogens as a component of a PhD research venture supported by the University of Florida.

Lucas said that the ozone treatment amused him largely that a second framework was bought to treat the water in the flood floor; the rest of the system includes an overhead hanging basket and boom watering system framework. A specially crafted bio-filter channel framework will give a last treatment of the leachate overflow from the overhead basket and boom watering system frameworks before the water is discharged into the lake. The bio-fillters are put to evacuate remaining hints of manures and different chemicals (i.e. fungicides, pesticides, plant development controllers, and so on.). The bio-filters and ozone treatment framework will recycle the pond water which will in the long run evacuate any synthetic deposits that have been beforehand released into the lake. The organization additionally introduced a pond air circulation framework that is intended to produce 9.71 complete turnovers for every day of all the water in the pond. The air circulation framework keeps up a uniform temperature, clarity and oxygen level all through the lake. It disposes of most pathogens, brings down turbidity and lessens pathogen levels, altogether enhancing this water source.

Basically, the two methods stated above are the other most robust methods of greenhouse water conservation aside from the watergy design. The watergy design has a top advantage in that it does not demand the necessity of external sources of energy in order to operate (Zylstra, 2011).

3 Watergy greenhouse control Methodology

The watergy greenhouse works to ensure an environment that is cool, wet and bright contrary to traditional greenhouses that offer hot conditions in cold regions. The watergy greenhouse and other humidification dehumidification greenhouses hence become even additionally viable even in desert areas. Current methods used to provide irrigation water in Arid areas including sinking of boreholes, redirecting of water from other sources are unsustainable in the longterm. The watergy greenhouse and other humidification dehumidification prototypes gather massive advantages from the following working methodology.

1. The treatment of Dry air in the greenhouse whereby the system traps dry air in humidifier concentrates allows the greenhouse to remain humid throughout the day. This kind of humidity inside the greenhouse reduces the levels of water usage in the greenhouse while at the same time providing an optimal humid and cool environment for the plants.

2. Apart from providing the plants with optimal growing conditions, the humid air also protects crops from Airborne contaminants. The humid air works to capture foreign contaminants such as spray, dust, pollen and insects.

3. The watergy greenhouse also produces a source for clean consumption water. It produces fresh water from its distillation process which is free from salt, chemicals and other mineral additives. 4. The watergy project also benefits from its operative methodology whereby it uses renewable sources of energy unlike other prototypes. Common prototypes rely on the national grid for provision of power but the watergy project uses solar energy.

5. The process utilizes the sunlight and saline water to run its processes.

6. Due to its water gathering and water saving initiative, the watergy project ensures water availability in the dry season.

7. Another major working methodology of the watergy project is the natural control of pests and pathogens in the greenhouse. This action reduces the need for pesticides in the farm

8. The system embraces economical production and thus in the process enables for financial savings in the farm.

4. Outline of the thesis

Modern methods of greenhouse water conservation are evidently more effective than traditional methods, however, additional techniques may be utilized for more efficient production.

5. Water treatment and desalination system in Greenhouse Model

5.1 Watergy greenhouse

Watergy is a bionic idea, immitating the biosphere inside a fenced in area, utilizing wind, rain and related energy scattering. It permits 85% reusing of irrigation system water, while amassing of CO2 prompts higher rates of photosynthesis. Further applications are plant safety, preparing of greywater, desalination and heat supply. Closed greenhouses are normally known as a probability of a more asset effective agricultural generation as far as water and energy is concerned. Water is the fundamental restricting variable of development in dry regions around the world, as it is the premise for sustenance creation and chief human life support. Worldwide populace development incites new innovations not just for more effective methods for water use and higher efficiency of farming, however particularly for future improvement of non developed regions. Developing costs for fossil fuels are the primary explanation behind reduced aggressiveness of plant production in Central Europe, where warming interests amid winter are a primary issue.

5.2 Watergy climate model

In a closed greenhouse, air trade with the encompassing environment is minimized, dissipated water is reused by buildup forms and the sunlight based warmth load is in part caught, put away, and can be utilized for warming procedures as a part of postponed time. However, using man made methods for cooling a nursery needs facilitate mechanical energy (i) for inner air dissemination between the vegetation zone and a warmth exchanger, (ii) to drive a warmth pump for cooling (iii) to drive course pumps for transport of cooling or warming media. Owing to this factor, as of not long ago just little diminishment of essential energy utilization has been picked up furthermore; water reusing must be paid for by an extra requirement for energy. Further focal points of a closed greenhouse are decrease of pest/pathogen control, effective utilization of CO2 and the likelihood of upgraded CO2 saturation in the closed environment.

The Watergy framework has been planned on the base of mathematical recreation of the energy and water parities including air mass exchange. The framework is as of now in the condition of improvement since the year 2003 when a model at the Experimental Station of Cajamar in the area of Almeria/Spain, was developed in an European Union supported examination venture. The fundamental creation surface is 200 m². It has been working in a closed state for around two years with French beans, bramble beans and okra. The primary inventive component is a cooling tower in the focal point of the nursery where amid the day time, hot air ascends from the vegetation zone, through the rooftop zone into the tower. To build the energy and water substance of the rising air, it is further humidified in the rooftop territory by sprinklers on an internal rooftop plastic layer.

From the highest point of the tower, the air falls back to the base of the nursery as it is cooled in a pipe by a warmth exchanger. The cooling media is water and is given from three capacity tanks of 5 m³ each outside of the nursery. Through the cooling procedure, the damp air consolidates and the dissipated water from watering system and from the sprinklers can be reused. Amid the night, the warmed water from the store streams backward bearing through the warmth exchanger, keeping in mind the end goal to discharge the warmth back to the nursery and to cool the store. The warmth exchanger is then humidified by further sprinklers, keeping in mind the end goal to increment the warmth discharge with extra evaporative cooling. As they are isolated from the vegetation, both sprinklers at the internal rooftop and in the tower can be bolstered with saline water keeping in mind the end goal to coordinate a desalination capacity. Water can likewise be overhauled amid the procedure, if polluted water is utilized for watering system.

5.3 Parameter estimation and discussion

Cooling process

The principle point of the cooling procedure is to keep the air around the vegetation at a level which permits ideal development conditions and to ruin transient overheating that would kill plants or parts of them (particularly blooms). By having a counterfeit supply of CO2 at saturations somewhere around 600 and 1200 ppm (which is somewhere around two and three times more than the climatic level), the greatest ideal development temperature is moreover lifted from 24 to 29° C. An improved proficiency of the passive cooling can be accomplished by expanding the heat discharged during the evening with the sprinkling of water in the warmth exchanger, as was done in the late spring. Nonetheless, there is a breaking point to the warmth discharge. The temperature of the cooling media can’t go underneath the outside evening time temperature values. Covering of the two bends demonstrates the best warmth discharge execution.

Dehumidification process

To permit consistent plant development in the nursery, the inward air needs perpetual dehumidification in parallel to the evaporation procedures. This is acknowledged by buildup on the coldest surfaces in the framework, particularly on the warmth exchanger (amid daytime) and the outside surface (amid night). The impact can likewise be utilized for water reusing and redesigning. The normal water interest for irrigation system in the Watergy model is about ~1.5 L/m2 d (generally low because of higher relative moistness in the nursery) and the water reusing rate (from consolidated water) is 65%. Furthermore, 10 % of the water was reused by gathering of water from soil waste. In examination with open field agribusiness, this is as of now a minimisation of water interest of 90%. This can as of now be considered as a water autarky mode, as the remaining water needs (coming about because of misfortunes in the buildup accumulation procedure and dampness misfortunes via air trade through the remaining spillages) can be given by the accumulation of downpour from the surface (in the test atmosphere of southern Spain).

The buildup procedure goes parallel to the cooling procedure, however other than the arrival of warmth, buildup seems just at the coldest parts of the surfaces. It ought to not show up on the vegetation surfaces as here, the primary part of the dissipation needs to take place. With respect to ideal plant development, a most extreme temperature is set and the temperature where condensation happens is for the most part under this constraining quality. This is the principle contrast to a sun oriented greenhouse, where buildup amid daytime can show up on the outside spread. The sun illuminates the spread and it is generally hot, however the inward temperatures can rise past the surface temperature. In the energy equalization of the greenhouse, the same heat that is discharged by the warmth exchanger is utilized to breakdown condensation.

6. Optimal Adaptive Control in Greenhouse model for Watery.

6.1. Optimal controller

A single closed greenhouse is a first prototype with the main purpose of producing water. The size of the greenhouse for the prototype is about 200 square meters and the structure is made up of galvanized iron with a polythene cover made of plastic. A transparent layer made of plastic has to be used as a secondary collector for the crops inside the greenhouse with water sprinkling system. The structure of the prototype is made up systems for measuring humidity, water flow, and temperature as quoted from (Wilcoxson 2013). In addition, other key components in the structure of the greenhouse prototype are sensors and actuators, which are used for activating model, based optimal controller system.

The greenhouse is closed to create a system that act as climatization that is powered by solar energy. Further, this system provides a water treatment cycle for the greenhouse. The system can use water from irrigation. The crop transpiration purifies the water when evaporating from the soil. Additionally, the secondary collector can also use saline water in evaporation to generate distilled water in the condensation chamber. The condensed water can be recycled to be used for irrigation again. This system therefore, generates a significant method for saving water and energy.

Optimal control of the greenhouse can meet the future demands in the structure and model of the greenhouse.

6.2. Parameter estimation

The application of relevant and quality controllers in greenhouses requires advanced models. The models require much attention from the greenhouse owners due to change in parameters like growth of crops, change in the layout, and finally, change in properties of the materials and modifications in the greenhouse. the estimation of the parameters in the greenhouse have to be kept in track by ensuring that, the accuracy of all parameters used are up to date

6.3. Greenhouse emulation

Before designing a new or expanding an already existing greenhouse structure, water availability has to be a determinant factor. A number of varying factors affects water usage in the greenhouse. The most essential variable in this situation is the solar radiation in the greenhouse. The irrigation system for the Greenhouse optimal adaptive controls for watery generate the supply of water and nutrients for the crop in the Greenhouse as suggested by (Schlueter 2016). The system supply precise amount of water to the crop as required. The basic requirements for this system is that, the incoming water is mixed with precise amount of fertilizers before it is supplied to the crops. The key component to keep in mind is that, each moment when water is delivered to a crop, the crop also receives fertilizer. Water and fertilizer are injected to the crop through use of pumps connected to the pipes running through the length of each row of the crops in the Greenhouse. the design of the tubing has a small diameter feeding one crop. This design ensures that the amount of water and fertilizer delivered to the crop is equal throughout the Greenhouse. Large greenhouses have a number of partitioned zones for watering. The water flows passed the crop zones to the root system.

Water application in Greenhouse is essential for integration of fertilizers in crop production system for hydroponic management. The watering management of Greenhouse is focussed on optimal water delivery over a number of growth stages of the plants through environmental changes over the production period to help in maximizing the plant yields. Additionally, the application of water in Greenhouse environment helps in optimizing the nutrients, which also promote the growth of plants to maturity for a promising harvest as quoted by (Schlueter 2016).

Generally, statistics from various researches conducted indicate that, plants comprise a range of eighty to ninety percent of water, and the availability of adequate and reliable quality water is very essential to a successful production of the crop. The minerals contained in the water at the source determine the quality of the water for the crop. Some sources of water include well, rainwater, dugouts, and water supply from city or town as suggested by (Wilcoxson 2013). The water from different sources contain different degree of acidity or alkalinity, which determines its quality for the minerals needed for the crop. In a practical view, water is a solvent, this property gives it the ability to contain and hold a certain percentage of soluble salts in a solution form.

The nature of fertilizers is in a soluble form of salts; therefore, growers provide plants with adequate nutrients by dissolving the fertilizers in water. Essentially, before using water from any source for Greenhouse production, it is important to test the quality of that water since; high quality water with adequate soluble minerals will provide good production of the crop. By testing the quality of water, the amount of salts available in that water determines the quality concerns of the water. Another factor that determines the quality of water for Greenhouse production is determined by the concentration of salt ions in parts per million for water, which is a unit of measurement for amount of dissolved ions in water, and besides that, they are also used in measuring amount of dissolved fertilizer salt nutrients in a solution form. In addition, milligrams of a solution is another mode of determining the nutrients level as dissolved ions in water. The test for water quality will also help in determining the pH value, acidity, and alkalinity of water. Once the water source has been verified for crop production in the Greenhouse, it is important to have a routine of testing the water to ensure that, in case of fluctuations in the quality of water, the production of crop is not compromised according to (Schlueter 2016).

Electrical conductivity of water can be determined by water quality testing. The amount of salts and ions dissolved in water determine the ability of the water to conduct an electrical current. If the concentration of ions and salts in water are high, it consequently indicates that the electrical conductivity is high for the water. The level of salts in water can be determined by electrical conductivity and this however, can be a very essential tool in determining water suitability for crop production, and for determining the fertilizer feed solution for the crop. Electrical conductivity can be a tool for determining the target of the nutrient solution on the root zone of the crop and this can be used for managing decisions regarding fertilizer delivery solutions for the plant.

Relative acidity and alkalinity contained in water determines the pH level for the water. The scale of measure for the pH value is from a level of zero to fourteen. If the number of the pH value is low, that indicates that the level of acidity for that water solution is high, and if the level of the pH value number is high that indicate that the amount of alkalinity is higher for the water solution. In most cases, the water supplies are alkaline with 7.0 to 7.5 as pH levels, which increases with increase in levels of bicarbonate. The level of the pH measure indicates the chemistry of nutrients and water solutions. Fertilizer solutions pH can be used in determining the solubility of the nutrients and how available the nutrients are to the plants.

The optimum pH level for a solution in relation to nutrients available for the crop ranges from 5.5 to 6.5. In adjusting the level of pH in a solution, acids such as phosphoric and nitric acids are used if it means that the adjustment is towards the higher level of acidity in the pH scale. Consequently, in adjusting the pH value for towards higher level of alkalinity bases such as potassium bicarbonate are used. While adjusting the pH level for feed solutions using acids and bases, the nutrients added by acids or bases should be accounted for when calculating the feed solution. In most cases, water supplies for Greenhouse crop production are alkaline and thus require the use of acids for pH correction.

Water analysis determines the amount of bicarbonate in water supply. The level of bicarbonate in water determines the level of acid required to determine the pH level. An appropriate target for pH nutrient feed is 5.8, which corresponds to a bicarbonate level of 60ppm. For instance, if the incoming water for the Greenhouse has a pH level of 8.1 and the bicarbonate level is said to be 208ppm, then 208ppm-60ppm=148ppm that will be required to be neutralized by the acid in order to reduce the level of the acid from 8.1 to 5.8. According to the analysis, the calculations have to be made for every sample of water based on the result of the analysis. Apart from nitric and phosphoric acid, hydrochloric and sulphuric acids are also used to adjust the pH value for the acids.

7. Discussions and result analysis for watergy in greenhouses

The advancement in the structure of the greenhouses require developments in sensors and actuators and the use of information. For instance, many growers use installed weighing gullets in the greenhouses to ensure that they keep track of evapotranspiration of the crops. In future, there is no doubt that, there will be further advanced innovations in response to increased operational demands on the structure and system of the greenhouse. Watergy in the greenhouse ensures proper modelling in the evapotranspiration of crops and make model parameters become adaptive for the greenhouse.

In discussion and result analysis of water supply in the greenhouse, an adequate supply of water is relevant for irrigation in the greenhouse. Water is also needed for irrigation, application of pesticide, evaporative cooling of the crop, and lastly for cooling and media preparation. Crops require satisfactory moisture for optimum growth. However, this factor is affected by many variables. The type of crops to be grown, the area to be watered, the environmental control system, and the weather condition of the place where the greenhouse is located determines the quantity of water required in the greenhouse according to (Balas 2016). In a practical view, the design of supplying water determines that water have to be injected in the greenhouse at the peak season of the year. Factors that determine the level of water required in the greenhouse include:

  • Solar radiation- the radiation level that reaches the plant is decreased by ten to forty percent because of gazing in the greenhouse. This factor causes a reduction in the transpiration rate.

  • Leaching- water usage in the greenhouse increases due to excessive water required to be supplied in the greenhouse to remove excessive fertilizer salts. Leaching significantly accounts for a greater percentage of water usage. The pattern of growing crops definitely affects the water holding capacity of the crop. This enhances the frequency of watering.

  • The type of irrigation system- an estimate of only twenty percent of the water irrigated in the greenhouse may reach the canopy of the crop. The grounds that are flooded conserve water by only reusing and recycling the excessive water applied.

The usage of water in the greenhouse can be done using a number of methods. The most appropriate method is by adapting low water usage irrigation system. Zoning water application is whereby water is injected at one section of the crop at a given time allowing water to be irrigated to a large number of plants. In case the wells have a shallow end flow, the storage tanks can be used to store water to be used in the greenhouse. Water in the storage tanks is then injected to the crops in the greenhouse to be used during daylight as suggested by (Balas 2016).

8 Conclusion and Recommendations

The watergy project aims at finding short-term solutions for the energy requirements and ecological influences of greenhouse cultivation. The project has achieved a major impact on reducing water demands for greenhouses as well as maintaining sustainable energy use. The benefits have been vast not forgetting that this project is more economical for farmers reducing the need for pesticides in farming. Comparing the Watergy project and other projects such as the Lucas farm, we find that the Watergy model is less expensive and also less technical. The greenhouse capability to maintain cool temperatures makes farming even in areas that experience highly volatile temperatures. Though the project has had massive success, further research can be done to ensure similar benefits at lower costs.

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