As mentioned in the previous section, the weather data in each station are interpolated to determine the temperature for the entire country. In terms of yield per area, the hydroponic production of tomato is found to be greater than open-field production. Hydro-ponic greenhouse tomato production is estimated with a yield of 195.3 kg/m2/y, whilst the yield in an open field is projected at 3.23 kg/m2/harvest. It is assumed that the duration of harvest for tomato is every 2 months during the year and that there are zero harvests during the summer period . Consequently, the estimated yield in an open field is estimated to be 9.69 kg/m2/y. The high yields of hydroponics production of tomato result from the controlled environmental conditions maintained within the hydroponic greenhouse, which allow for continuous production all year round. The advantages of hydroponic production will vary depending on the operational parameters under which the crop is grown and is not unique nor limited to tomato alone. Similarly, water utilization in a hydroponic greenhouse and open field production of tomato in Qatar is compared for various seasons. The results summarized in Table 8 indicate that less water demand is required in hydroponic production in comparison to open field production. Therefore, it is considered as a more efficient farming method, due to the fact that the hydroponic system delivers the water more resourcefully, with a larger percentage of the water going to plant evapotranspiration . The tomato crop evapotranspiration per season for open-field agriculture and hydroponic greenhouse as a growing method is summarized in Table 9. The result demonstrates that hydroponic is more efficient than open field by 5%, where it saves around 4000 mm/day/season in the summer.
Due to the controlled nature of the climate within a greenhouse, the amount of crop water lost by evaporation and transpiration processes would be reduced. All greenhouses have the capability of reducing evapotranspiration through increasing humidity and entrapping moisture level, flood tray physically blocking wind, and reducing the solar radiation by filtering out some direct sunlight that reaches the plants; this is due to the greenhouse’s protective covering that performs all of these three functions. Results for energy consumption per each component in a hydroponic greenhouse for tomato production in Qatar are illustrated in Appendix C. Due to the availability of 40 ha for the production area in Agrico farm, it requires more energy for cooling in comparison to other three farms. Moreover, the energy for supplemental artificial lighting is assumed to be constant for all seasons, as it set to the optimal value required in tomato production. Furthermore, the results demonstrate that most of the energy consumption in the hydroponic greenhouse is due to the cooling loads. This is primarily due to the fact that the greenhouse is located in AlKhor, in the North of Qatar, an area which can have average temperatures of 40 °C in the summer and 20 °C in the winter. However, if greenhouses are to be located in more reasonable climates that are closer to the greenhouse set point temperature, they would experience a lower energy requirement. The other use of energy for the hydroponic greenhouse is for supplemental artificial lighting, which is used to maximize crop yield and maintain consistent production year-round. Some systems use supplemental lighting to create a 24-h photoperiod, especially during the first few days of plant growth, whereas others may use supplemental lighting for only a few hours a day . In addition, small and low-output systems may not use artificial lighting at all. However, in this study, it is assumed that the maximum yield is desired . In addition, the other energy components that affect total energy consumption in the hydroponic greenhouse include the energy used to pump groundwater from approximately 40 m depth for irrigation purposes, and the energy used to distillate brackish water using reverse osmosis technology.
The energy consumed by RO plants is calculated only for SAIC farm due to the onsite availability of two RO plants with a capacity of 370 and 700 m3/day, and by considering a value between 0.5 to 3 kWh/m3 for specific energy consumption . Furthermore, one of the objectives of the study is to observe how changes in technology or production methods can affect the utilization of water and energy in farms. Accordingly, water and energy consumption are also estimated for the four farms assuming an open field for tomato production. The overall energy consumption in both open field and hydroponic greenhouse are summarized in Table 10. The main observation demonstrated from the assessments is that the node is affected by seasonality, growing method and size of the production area. Different seasons will have different water and energy consumption, this is especially noticeable in an open field scenario, where in summer, open field farms will suffer from high temperatures leading to high evapotranspiration and hence higher water demands. Furthermore, as stated previously, depending on the production method used for tomato, a large variation within water and energy consumption exists. The production area also influences the overall energy and water demands, where Agrico is the largest farm in comparison to the others with an area of 40 ha with corresponding hydroponic energy needs of 5133.3 kJ/kg/year. Although SAIC farm has a smaller area of 2.8 ha, it still consumes large quantities of energy in the hydroponic greenhouse due to the two onsite RO plants.Increasing consumption of natural resources and energies, global environmental problems have appeared. Nowadays, many people face major environmental issues. Especially water problem is spread around the world . Approximately 2.4 billion people are in strict water-stressed condition . The deterioration of water environment has been accompanied by the factors concerning health hazard and agricultural production. On the other hand, two-thirds of fresh water in the world is irrigation water for agriculture to provide foods. Because of these reasons, food production is strongly close to water issues. Hence, preservation of water quality and economy is important ranging from human life to agriculture. According to these various studies, the assurance of high water quality is serious issue to be solved.
In agriculture, advanced technique against environment stress for high quality vegetable production has been discussed by many researchers , and they mentioned that it is more important to control nutrient solution in water circulation systems. The pH in nutrient solution is related to the plant growth and nutrient components in hydroponics. The nutrient solution used in hydroponics has been related to pH, electrical conductivity , ion concentration, temperature and additional chemical compounds. Hydroponic system for agricultural production has several advantages such as it can use unsuitable area, independence of environmental conditions and easy controlled root systems. Moreover, plant factories adopt hydroponic system because the plant factories need cultivation systems to control plant growth and produce high quality. In this study, we focused on nutrient solution especially water structure. Water is a unique liquid in our world and has a highly structured liquid . Recently, many water analyses were carried out to investigate water structure to know hydrogen bonding and hydration effect. For example electrolytes solution is assessed through viscosity , thermally stimulated current method and 1 H NMR spectroscopy . One of dynamic status in water expresses viscosity.Therefore, viscosity as one of the fundamental macro parameters in a solution was evaluated for water status such as ion concentration, temperature and pressure . The absorption of water is essential for the growth of most plants because they lose large amount of water daily. Plant cells constitute approximately 90 % of water. Therefore, water state surround root systems of crops is important in agricultural production. However, the relation in water structure including the state of hydrogen bound formed water molecules and physiological function of plant growth has not been clarified. As the viscosities decreased in the nutrient solution for plant growth, recent studies have suggested that the uptake of ions and water by plant roots would be easier . Other research has demonstrated that the thermally stimulated current method, the method of water analysis, has carried out for hydroponic system . For growth of plants, ebb and flow tray the using water to prepare the nutrient solution is limited by water quality . Therefore, quality and structure of water for agricultural use is expected to continue improving.
However, water structures are difficult to apply hydroponic system due to complex relationship between roots and waters. For this purpose in this study, nutrient solutions in various concentrations of ions were compared concerning viscosity. In addition, viscosity of nutrient solution was measured not only in different concentration but in different temperature. The data obtained from this experiment will be to control nutrient solution in hydroponic system for production of high quality vegetable and stable production.Evaluation of water structure influenced by ion concentration is complex phenomenon such as ion-water molecular interaction and states of hydrogen bond in water. In general, viscosity is one of general value which are information regarding ion-solvent interaction and fundamental state deciding dynamics property of water structure making or breaking characteristics. Therefore, the viscosity is one of the fundamental parameters deciding dynamic property in the water. In this experiment, viscosity was focused and measured with a digital rotary viscometer as adapted measurement of low viscosity. LCP was used for spindle, and revolution speed of the spindle was 100 rpm. The samples of nutrient solutions were taken 18 mL into sample adaptation by a pipette. The viscosities were recorded during 7 min except 3 min after starting an analysis. Averages of viscosities were calculated using last 2 min . Because water temperature influences the viscosity of solution, water temperatures of all samples were measured before measuring viscosities by thermocouple. The water temperatures were controlled by a low-temp thermostatic water bath circulated surround sample adapter. The average of all plots was recorded and all samples were carried out in triplicate. For comparison of viscosities in different temperature, nutrient solution fixed its concentration and temperature only changed over 5-35 o C.In relation between viscosity and EC value, the viscosity significantly increased with the increase in the EC value . Regression analyses showed that there were significantly positive correlations between viscosities and electrical conductivities . In general, this tendency of increasing viscosity explains that main cause was the different concentration of ions due to structure making effect. This result suggested that nutrient solution changed its viscosity during cultivation period. Without automatic managing ions concentration, nutrient solutions during cultivation period increase or decrease at end of growth period. According to previous study, hydration of inorganic ions can assort into two groups, one is “positive hydration” and the other is “negative hydration”. These groups have different behaviors in water. “Positive hydration” forms ordering water structure by bivalent, trivalent ions and alkali ions. On the other hands, “negative hydration” behaves structure-breaking on the water structure by univalent ions . Concentrations of positive hydration ions, especially magnesium and calcium, dissolved nutrient solution. This result indicated that nutrient solution was observed higher viscosity due to shift concerning ion concentrations. Antibiotics are widely used in medical treatment, veterinary medicine, aquaculture and other areas.
The global annual consumption of antibiotics in agriculture, aquaculture, and livestock husbandry reached 100,000–200,000 tons and the amount of antibiotics used worldwide is expected to reach 106,000 tons in 2030 . However, 30–90% of antibiotics are excreted in urine and feces as parent compounds or metabolites . Therefore, antibiotics are constantly released into the environment. Existing studies have shown that antibiotics are widely found in water environments , posing a great threat to humans, animals and aquatic habitats . When Iris pseudacorus and Typha were exposed to 2 mg/L of furosemide, the plants have a positive growth rate at the end of 21 days experiment . Concentrations of fluoroquinolone antibiotics , particularly levofloxacin , in the upper ng/L to lower μg/L range are frequently detected in wastewater . LOFL is widely applied as an antidysenteric and antibacterial agent and for the treatment of pneumonia and immunodeficiency virus . Existing research has shown that the environmental fate of FQs is influenced by photodegradation, adsorption, and biodegradation.