Starting from the lowest line in Figures 10, it is shown that a poor P:N ratio results in significantly lower efficiencies than the other combinations, for all levels of variation. The NFT system, with its lower system volume, shows the highest sensitivity to variation . The 3000 m2 HPS scores lower than the reference due to its relatively low fraction of nutrients supplied by the fish . The addition of the RO system for a 2500 m2 HPS resulted in only a small performance difference with the reference , due to the low availability of nutrients in the RAS when demand is high in summer. Therefore, RO has limited added value in northern latitudes. The scenarios with buffer show very low sensitivity to transpiration variation, of which an AD buffer for the NFT system shows the greatest performance increase . For the DWC system, the AD buffer outperforms the RAS to HPS buffer, despite requiring less than a sixth of the volume. The production of tomatoes was also simulated and briefly explored to support the theories brought forward in this study. The corresponding methods, results and discussion can be found in Appendix 5. For a tomato crop, a similar decline in AP efficiency is found with increasing variation in the seasonal transpiration. However, the changes in the greenhouse parameters resulted in a smaller difference in variation than with lettuce. Most of the GH parameters tested in this study had only a small effect on the transpiration variation and could, therefore, be readily changed to save energy. This includes the thermal insulation of the cover, minimum temperature, heat storage, and screens, as shown by the smaller differences in transpiration in figure 6.
Further increasing the bounds of maximum humidity lowered the performance of the aquaponics system the most and is,potted blackberry plant therefore, not advised for low volume systems. In agreement with Dijkgraaf et al. , it is in most cases better to have a system that requires supplementation rather than dilution. For scenarios with a high CV as a result of energy savings, an increase in the HPS area is a suitable measure to decrease dilution requirements, with an acceptable loss in nutrient self-sufficiency . The same can be seen in the outcomes of Goddek & Körner , where the HPS area is increased relatively more than the decrease in transpiration rate between the different scenarios.The addition of a buffer for the direct flow from the RAS to the HPS reduces the variation in this flow, which leads to a significant increase in performance compared to the reference . However, the volume required to have this effect is substantial, with more than 10L/m2 required for each percentage point of performance increase. The buffer for the AD output has shown similar benefits with a much smaller volume of 0.6 to 0.75 L/m2 for an increase of one percentage point, which greatly reduces the estimated construction costs. The AD to HPS buffer increases performance by linking the nutrient supply to the seasonally variable demand. While this mainly influenced phosphorus, the NUE of N was also improved in some scenarios due to lower dilution requirements from phosphorus peaks. The RAS to HPS buffer flattens the peaks of NO3 in the RAS, which is especially beneficial for sensitive fish. It is not yet studied how the water quality is affected by the long term storage suggested here. This concerns both food safety aspects, as well as chemical reactions that could change the nutrient composition during storage.
It is expected that both chemical and microbial reactions continue in the storage tank, which could decrease the water quality and safety . If required, several adjustments can be made to lower the risk of pathogens in the storage tanks, such as temperature and pH control and disinfection. buffering the brine flow of the RO system was not explored in this study, but we expect a similar increase in performance as for the RAS to HPS buffer. While not only resulting in a more concentrated inflow than buffering RAS water, and thus a smaller required buffer, it would allow the RO to be activated more during the winter. This is when the nutrient concentrations in the RAS are generally the highest, while RO cannot be used as it would result in a nutrient surplus and subsequent dilution in the HPS. buffering the brine flow could likely flatten the nitrate peaks displayed by Goddek & Körner .The scarcity of freshwater in most countries is an increasingly acute problem, particularly as their populations continue to grow rapidly and place higher demands on water resources. The agriculture sector is the largest consumer of water supplies. Agriculture consumes about 87% of the total water consumption in the Middle East and North Africa region. In the Palestinian territories, the total estimated water used for agriculture is not exceeding 150 million cubic meters annually. This amount represents 45% of the total water consumption, which is reflected directly on the limited prospects for the development of irrigated agriculture that can have an important economic, social and political role in rebuilding the Palestinian economy. Wastewater has to be reclassified as a renewable water resource rather than as a waste.Reclaimed wastewater is a treatment of different types of wastewater for reuse application.
The climate change affect in the reuse application. Climate change affect directly or indirectly on the wastewater reclamation and its reuse to conserve freshwater resources. The direct climatic factors include temperature, precipitation, sea level rise and severe conditions, whereas the indirect factors related to management and operation activities as water use control, greenhouse gases and adaptation measures. Epuvalisation is a French word that means a biological treatment technique that comes from the contraction of two French words: épuration and valorisation ; it uses plants,not only to purify water but also for the growth and production of these plants. The plants roots act as a physical filter which holds the suspended matters. Epuvalisation has been applied with ample success in many Mediterranean countries and in Belgium as a tertiary purification process of secondary treated effluent utilizing different plants. The technique was applied for treated wastewater. In addition, it was used for Sr/ Cs in wastewater treatment. This technique consists of hydroponic plantation in channels. The wastewater flows into the channels and keeping a direct contact with the plants’ roots. The roots are utilized as bio-filters and adsorbents for the removal of nitrogen, phosphorus and other macro-nutrients. In addition, toxic elements and salts can be removed from wastewater by an accumulation into the plant tissues. The system mechanism consists of gravitational effluent flowing through open channels to keep the water well aerated. The channels host the plant roots not only for water absorption purposes but for trickling and biological filter functions as well. The roots play a dominant role in taking up the nutrients, thus decreasing the total dissolved solids, which includes nitrogen and phosphorus.
This technique can be operated in closed or open loop modes. The open loop system is less efficient in the removal of nutrients and salinity due to minimal contact time, while the closed loop system is more efficient because of a relatively longer retention time. The system can also produce two valuables, water and plant valorization. Water valorization which is the complementary treatment can make the water suitable for non-restrictive irrigation and plants valorization in which the system will produce. Valuable plants ; seed; animal feeding under given and strict conditions regarding toxic compounds such as heavy metals or any other compounds that could enter the food chain. In our lab, we have investigated the Rosemary plant using the same technique and same water type. The results emerged from this study demonstrated a good adaptation with increasing rate of all plant growth parameters. The technique was applicable using brine water for Basillicum irrigation which highly adapted in brine water and biomass production. The aim of this experiment was to investigate the ability of geranium plants to purify a secondary treated wastewater using Epuvalisation technique in greenhouse environment. The main objectives of this study were to plant geranium plants in epuvalisation system using secondary treated wastewater and fresh water and to determine the plant growth parameters and plant tissue analysis during and at the end of the seasons. The physical, chemical and biological analysis for influents and effluents of both secondary treated wastewater and fresh water as blank are determined during the study period. Comparison of the plan parameters between the two irrigation systems is used as a tool to determine the efficiency of the use of secondary treated wastewater in epuvalisation system.At the end of the experiment, the plants were harvested and separated into roots, leaves and stems and then dried in the air. The dried samples were used for chemical plant tissue analysis. The chemical analysis included total nitrogen, total phosphorus, sodium, tall pot stand chloride and potassium. A standard method for soil and plant analysis was used for chemical plant analysis.The results of the Irriblend-DSW simulations offered valuable information for the fertigation management of the demonstrative case studies presented, in which DSW and conventional waters with different quality, price, and availability are used. Once the requirements and available resources for the production systems were characterised, the DST could identify which combinations of water and fertiliser could be viable from a technical and economic perspective.
Both case studies involve intensive production systems with great land and water productivity,but with substantial investment and operational costs. The DST provides the value of PPI for all technically feasible combinations, but only those with a PPI above the profitability threshold would be economically feasible. For the NFT lettuce case, the DST showed that only half of the technically viable options were likely to be profitable,whereas for the GH tomato, all the solutions were above the profitability threshold. However, the real contribution of the DST is not merely filtering out unfeasible options from an economic perspective but also to offer information on how to optimise the use of available resources and maximise profits. Navigating the interactive plots,it can be seen that in both cases, increasing the amount of low-quality water over the optimum percentage drastically reduces the PPI. In fact, the EC of the optimal solutions was close to the crop salinity threshold, since maximal addition of cheaper brackish water substantially reduces costs without yield loss. In the NFT lettuce case, this limit was 35% of brackish water in the blend, as percentages over it rendered the crop non-profitable. This implies that, because the availability of conventional fresh water is becoming very scarce, without the supply of DSW, production would not be viable. In the case of GH tomato, although all solutions surpassed the profitability threshold, the DST showed that adding more than 65% of brackish water in the blend causes the EC to increase above the salinity threshold, which can result in a decrease in net profit over 2 × 103 €/ha/cycle. It is important to note here that, for the calculations, we used the mean GH tomato market price in the 2017–18 season. For a crop market price below 0.45 €/kg,we would have found combinations with the PPI below the profitability threshold among the technically viable ones as in the case of NFT lettuce. Supplementary material related to this article can be found online at doi:10.1016/j.agwat.2021.107012. Information about fertiliser selection and cost for each water blend derived from these simulations was relevant for fertigation management. In both cases, the data showed that the amount and type of fertiliser required increased as the percentage of DSW increased in the water blend. However, this cost increase is lower than that owing to the DSW cost. The increase in fertiliser cost was approximately 0.06 €/m3 for both the NFT lettuce and the GH tomato when moving from 35% to 85% of DSW in the water blend, whereas the increase in water cost was over 0.22 €/m3 in the said percentage range. Therefore, notwithstanding that fertilisation programmes and even systems require adaptation to DSW, the fertiliser cost overrun derived from the integration of DSW did not seem to pose a major threat to profitability.