Water Productivity Efficiency Research Articles

Optimal Design of Air Treatment for an Adsorption Water-Harvesting System

In some areas where access to water is difficult, such as arid regions, it is a feasible measure to acquire water from the air. In this context, a system for water harvesting from the air was designed and manufactured. In order to find the optimal operation parameters of the system, the humidity–enthalpy diagram and the dehumidifier computation software (V2.0, Win7) were adopted for the optimization work. The air treatment process of the system was analyzed and calculated by using the professional software provided by the dehumidifier company. Operation modes of ‘powerful mode’ and ‘economic mode’ were defined in the computation work, which are represented by the water production amount and efficiency (water production per power consumption), respectively. According to computation analysis, the relationships between the main performance indicators and the system design/operation parameters were obtained. By considering the heating power limitation of the system, the wheel dehumidifier rotation speed of 8 rph (revolutions per hour), zonal area ratio of Ap/Ar = 2, and the optimal airflow ratios in different relative humidity (RH) environments, together with the outlet air parameter settings of the surface cooler, were finally defined.

Alternate wetting and drying: a water-saving technology for sustainable rice production in Burkina Faso?

With emerging water scarcity and rising fertilizer prices, optimising future water use while maintaining yield and nutrient efficiency in irrigated rice is crucial. Alternate wetting and moderate soil drying irrigation (i.e., re-irrigation when the water level reaches 15 cm below the soil surface) has proven to be an efficient water-saving technology in semi-arid zones of West Africa, reducing water inputs without yield penalty. Alternate wetting and severe soil drying (AWD30), by re-irrigating fields only when the water table reaches 30 cm below the soil surface, may further reduce water inputs compared to farmers’ irrigation practices (FP). However, acute soil drying may impair fertilizer use efficiency and reduce the bio-availability of some key nutrients. This study assessed the potentials and risks associated with AWD30 for smallholder rice farmers in the semi-arid zones of West Africa. We conducted 30 on-farm field trials over three seasons (wet and dry seasons of 2019, and dry season of 2020), in Kou Valley, Burkina Faso. We assessed yield, water productivity, nutrient uptake, and use efficiency under AWD30 and FP. In FP, farmers maintained their fields submerged as frequently as possible according to the scheme-dependent water provision schedule. With AWD30, irrigation frequency was reduced by 30%, however, soils were seldom completely dried due to a shallow groundwater table. Compared to FP, AWD30 reduced irrigation water input by 37% with no significant effects on grain yields (average of 4.5 Mg ha−1), thus increasing average water productivity by 39%. Both irrigation management practices provided comparable crop uptake of N, P, and K, and use efficiencies of applied N and P. However, the N content in straw and the P concentration in grain generally increased with total water input (rain + irrigation). We conclude that at locations with a shallow groundwater table, AWD30 can effectively save irrigation water without significantly reducing the grain yield and the use efficiency of applied mineral nutrients.

A reduced model for pilot-scale vacuum-enhanced air gap membrane distillation (V-AGMD) modules: Experimental validation and paths for process improvement

A fast and robust computational model of a spiral-wound vacuum-enhanced air gap membrane distillation (V-AGMD) module at the pilot-scale is proposed and implemented. In contrast with data-driven models available in the literature, a physics-based approach is adopted for more reliable generalization beyond the validation dataset. A total of 86 experimental results, of which 41 are described in this work and 45 come from independent sources available in the literature, are used in the validation effort with quite favorable results. With the confidence on the robustness of the methodology due to the wide range of operational parameters and the use of spiral-wound modules of four different sizes included in the validation comparisons, a physical analysis is conducted varying the air gap pressure, the number of feedwater channels, the feedwater flow rate, and the membrane area. Improvements of up to 60% in both water productivity and energy efficiency can be achieved by intensifying the vacuum in the air gap or decreasing the number of feedwater channels. These parameters achieve performance gains due to less resistance in the air gap for vapor to migrate through it, in the former case, and a reduced temperature polarization effect, in the latter case. Smaller flow rates favor energy efficiency at the expense of water productivity by simultaneously decreasing transport-phenomena-related irreversibility and the partial pressure difference across the membrane and the air gap. In addition, this tradeoff between energy efficiency and driving force is shown to lead to an optimum value for the membrane area beyond which the permeate flow rate through the membrane starts to fall due to the small driving force. An illustrative case is predicted to achieve energy efficiency metrics, such as a gain-output ratio of 12.7, competitive with multi-effect distillation.

Integration of proton exchange membrane fuel cell with air gap membrane distillation for sustainable electricity and freshwater cogeneration: Performance, influential mechanism, multi-objective optimization and future perspective

Proton exchange membrane fuel cell (PEMFC) converts vast majority of hydrogen energy into waste heat, resulting in energy wasting, membrane drying and even lifetime shortening. Herein, air gap membrane distillation is proposed to immediately remove and harness the waste heat from PEMFC for additional freshwater production. By quantifying the irreversible thermodynamic and electrochemical losses, mathematical formulas for the water production, power generation and overall efficiency are derived to evaluate the system performance. After a rigorous model validation, the performance feature, feasibility and competitiveness of the proposed system are examined. The integration system achieves a peak power density 23.69 % higher than that of a single PEMFC at 353 K, with a corresponding increase in exergy efficiency by 3.61 %. In addition, the influential mechanisms of the PEMFC operating conditions, air gap thickness, coolant temperature, and properties of the proton exchange membrane and hydrophobic porous membrane are investigated to discern potential avenues for further performance improvement. The gradient-based local sensitivity analyses further determine the optimal parameter regulation strategies for different output targets. The economic study indicates that the levelized costs of water and electricity over the total lifecycle are 21.53 $ m−3 and 0.061 $ kWh−1, respectively. The multi-objective optimization, integrating genetic algorithm and the technique for order preference by similarity to an ideal solution, maximizes the exergy efficiency and output power density while minimizing the initial investment cost per unit area, with values of 42.84 %, 0.975 W cm−2, and 27.33 $ cm−2, respectively.

Water saving rice cultivation using sheet-pipe subsurface irrigation

Water saving in rice cultivation has assumed paramount importance, especially in the context of climate change. The introduction of sheet-pipe technology in Indonesia heralded as an innovative subsurface irrigation and drainage system, is poised to revolutionize how to manage this vital resource. Our study was designed with two primary objectives: first, to investigate how rice plants respond when water levels are deliberately reduced using the sheet-pipe technology; and second, to comprehensively analyze water productivity and water use efficiency in comparison to conventional flooded rice cultivation systems. We conducted two distinct experiments: one employing sheet-pipe subsurface irrigation (SSI) and the other utilizing conventional flooded irrigation (CFI). In the SSI setup, the water level was maintained at a depth of 5–10 cm below the soil surface 20 days after transplanting to harvesting. With this setting, the soil moisture was maintained at around 85–95 degrees of saturation. On the other hand, the CFI approach involved water flowing directly over the soil surface, with the water level consistently maintained at a mere 2–3 cm above it. Interestingly, while the SSI method did lead to a reduction in yield, it has significant benefits. Our results showed that a reduction in yield was observed for the SSI 15.5–18.6 % lower compared to the conventional method (CFI). However, the SSI is environmentally benefit compared to the conventional method by reducing 37.5–50.5 % in water irrigation, increasing water use efficiency (WUE) up to 70.8 %, and improving 3.2–10.4 % in water productivity. Our findings reveal that optimizing water conservation may have a disadvantageous effect on rice yield, indicating the importance of optimal water level. Future research to find the optimal water level that balances yield production and environment is required, especially to adapt to dry and warming climate change in the future.

Composite porous 3D foam for solar-driven atmospheric water harvesting in low humidity natural environment

Solar-driven atmospheric water harvesting (SAWH) has been recognized as a promising strategy to alleviate the freshwater crisis. Herein, we developed an efficient porous polymeric foam, LiCl@CCP-PPy, which has low preparation cost, strong adaptability and portability, and is very suitable for use as a wicking material in SAWH systems. LiCl@CCP-PPy contains abundant –NH2 and –OH groups. These hydrophilic groups and excellent pore structure (porosity is 80.22 %) make it have a good moisture absorption effect even in low humidity environment. The moisture absorption capacity can reach 2.86 g/g at 35 % RH and 25 °C, and 4.48 g/g at 25 °C and 90 % RH. The saturated water absorption effect was 27.48 g/g. LiCl@CCP-PPy can be scaled up for production. In addition, LiCl@CCP-PPy has a high light absorption rate of more than 90 %, and the strong photothermal conversion ability of Polypyrene (PPy) enables the material to warm up rapidly under natural light, thereby accelerating the desorption process (96 % desorption rate at 1 kW/m2 for 3 h). Based on the above properties, LiCl@CCP-PPy was applied to the Tengger desert in northwest China. The final water production efficiency was 0.64 L/m2/d, and the collected water quality met the international drinking water standard.

Optimizing irrigation and nitrogen fertilizer management to improve apple yield, quality, water productivity and nitrogen use efficiency: A global meta-analysis

Inappropriate strategies in water use and nitrogen (N) fertilizer application in apple production can decrease apple yield, water productivity (WP), nitrogen use efficiency (NUE), and quality, leading to severe environmental pollution. However, there is a lack of systematic analysis on the effects of water use and N fertilizer inputs on apple yield, quality, WP, and NUE at the global scale. Therefore, we conducted a comprehensive meta-analysis with 1834 observations from 72 published studies across 18 countries to assess the effects of water use and N inputs on apple yield, quality, WP, and NUE. We aim to quantify the potential for water-saving and N-saving for global apple production. Our results showed that the global average apple yield, organic acids (OA), total soluble solids (TSS), vitamin C (VC), firmness (FN), WP, and NUE were 34.7 t ha−1, 0.51 %, 13.9 %, 4.7 mg 100 g−1, 7.4 kg cm−2, 6.8 kg m−3, and 214.5 kg kg−1, respectively. Reducing above-optimal water input to optimal water input may increase apple yield by 19.4 %, WP by 36.1 %, OA by 12.5 %, TSS by 8.4 %, VC by 17.5 % and FN by 9.8 %, respectively. Reducing above-optimal N inputs to optimal N inputs may increase apple yield by 8.9 %, NUE by 48.1 %, OA by 10.7 %, TSS by 6.1 %, VC by 13.3 % and FN by 5.2 %, respectively. The overall global mean water-saving and N-saving potentials for apple production were 20.4 % (136 mm less water irrigated) and 37 % (203 kg ha−1 less N fertilizer used), respectively. Our findings provide guidance for water use and N fertilizer management of apple production and can thus help to improve/ maintain yield and quality for greatly saving water and N fertilizer.

Water and nitrogen supply at spatially distinct locations improves cotton water productivity and nitrogen use efficiency and yield under drip irrigation

The location of water and fertilizer supply directly affects the distribution of soil moisture and nutrients, thereby affecting crop yield and fertilizer use efficiency. However, the impact of water and nitrogen (N) supply location on cotton water and N use efficiency and yield is not yet clear, especially under drip irrigation conditions. A field experiment was conducted in 2022 and 2023. Four water and N supply patterns were set as: water and N supply at the same location (narrow row (PN) or wide row (PW)), water and N supply at spatially distinct (SD) and spatially and temporally distinct locations (STD). Soil water and N leaching, cotton root growth, water productivity (WP) and recovery efficiency of N (REN), and yield were quantified. The soil moisture and NO3--N vertical distribution range (0–60 cm) were deeper at the same location for water and N supply than at spatially distinct locations for water and N supply (0–40 cm). Compared to water and N supply at the same location, supply at spatially distinct locations significantly increased cotton root weight, root length density, and root surface area. In addition, water and NO3--N leaching of water and N supply at spatially distinct (SD and STD) were 12%-50% and 32%-59% lower, respectively, than those from the same location (PN and PW), while the yield and WP increased significantly by 7%-11% and 7%-10%, respectively. The REN of water and N supply at spatially and temporally distinct locations was the highest. Therefore, water and N supply at spatially distinct or spatially and temporally distinct locations can improve water productivity, recovery efficiency of N, and yield of cotton, and reduce soil water and N leaching loss under drip irrigation.

Simultaneous production of electricity and potable water underwater by integrating concentrating photovoltaic with air gap membrane distillation

This paper combines underwater concentrating photovoltaic and air gap membrane distillation, enabling the simultaneous production of electricity and potable water in underwater environments. Given its submerged nature and absence of land occupation, it proves particularly advantageous for land-deficient regions with limited access to electricity and potable water, such as islands and Coastal cities. It primarily comprises innovatively designed underwater solar concentrators featuring extensive light interception angles, photovoltaic modules, and membrane distillation units. It utilizes exhausted heat from photovoltaic modules to separate clean water from seawater via membrane distillation process. Furthermore, it is engineered to prevent any contact between metal materials and seawater, thereby mitigating the risk of corrosion. An experimental setup with photovoltaic cells’ areas of 0.006 m2 is developed and tested in the laboratory and under real weather conditions to assess its performance. The steady-state experimental findings indicate that as solar irradiation increases from 500 W/m2 to 900 W/m2, its electricity generation efficiency ranges from 9.0% to 9.7%, while the water yield efficiency ranges from 32.8% to 35.1%. Besides, outdoor experiments demonstrate that its power output during normal incidence ranges from 38.89 W/m2-85.56 W/m2, with an average electrical efficiency of 10.5%. Its average potable water yield reaches 0.537 kg/m2/h and average water production efficiency reaches 48.3%.

Optimizing irrigation and nitrogen management improves soil soluble nitrogen pools and reduces nitrate residues in a drip-fertigated apple orchard on the Loess Plateau

Appropriate water and nitrogen fertilizer management is crucial for achieving sustainable development in the apple industry. However, the soil nitrogen supply capacity and residual nitrate characteristics under drip fertigation remain poorly understood. Therefore, this study aims to (1) investigate the coupling effects of irrigation and nitrogen levels on the concentrations and distribution characteristics of soil soluble nitrogen fractions and residual soil nitrate; (2) explore the relationships between Christiansen uniformity coefficient (CU) of soil nitrate and apple yield, water productivity (WPc) and nitrogen use efficiency (nitrogen agronomic efficiency, AEn). The field experiment was conducted in a drip-fertigated apple orchard starting in 2017, which included two irrigation levels, 85% (W1) and 100% (W2) of field capacity (FC), and four nitrogen rates, 0 (N1), 120 (N2), 240 (N3) and 360 (N4) kg ha–1. The results showed that nitrogen inputs significantly increased soil soluble inorganic nitrogen and soluble organic nitrogen (SON) contents. However, the SON content significantly decreased when 360 kg N ha–1 was applied, particularly at W1. The maximum nitrate accumulation in the 0–3 m soil layer at N4 reached 2540.97 kg ha–1 in 2021, but the maximum value decreased to 1251.62 kg ha–1 in 2022 due to extreme rainfall. The average CU of residual nitrate across irrigation levels in the 0–3 m soil layer was highest at N3, with values of 0.68 and 0.57 in 2021 and 2022, respectively. High irrigation level increased the diffusion distances of nitrate both vertically and horizontally, resulting in a significant effect on CU. Apple yield and WPc first increased and then decreased with increasing nitrogen rates, while AEn consistently decreased, but they were all greater with a higher CU. The recommended combination of irrigation and nitrogen application was 85% FC and 240 kg N ha–1, which can achieve the dual goals of enhancing soil nitrogen supply capacity and minimizing environmental risks while improving orchard productivity.

A gravity-induced desalination technology effectively improving the freshwater production efficiency of freeze desalination

Low desalination efficiency and water production efficiency limit the commercial application of freeze desalination (FD) technology. In this study, three freezing temperatures were set to carry out single-stage progressive freezing desalination of brackish water in southern Xinjiang, China. The ice were melted using conventional methods and gravity-induced desalination (GD), and the salt migration law during the icing and melting process was studied. The effect of GD technology on the improvement of the output of frozen desalinated produced water was quantitatively analyzed using scenario simulation. Experimental results showed that salts accumulated towards concentrated water during FD process. The ice total dissolved solids (TDS) increased with decreasing freezing temperature, which was linearly and positively correlated with the raw water TDS. GD efficiency was significantly affected by the salt concentration of ice crystals. In the first stage (the first 450 mL), ice-melt water was salt explosive dissolution, with salt drained mass accounted for more than 85% of the total salt mass. During GD process, exponential decay of ice-melt water TDS (TDSI) was observed with increasing ice-melt water amount. Through the simulation of the two exponential equation scenarios, it was found that Scenario II (mixed water TDSI as the target value) had significantly higher water yield and production rate than Scenario I (TDSI as the target value), with an increase of more than 23%. The algebraic relationship between TDSI of mixed water and the amount of ice-melt water was derived. GD technology can effectively improve the freshwater output efficiency of the FD process, which is manifested by the fact that the ice crystals of the FD process cannot produce freshwater using conventional melting. Scenario II can produce freshwater as high as 69.83% of the total amount of the GD ice-melt water. The GD technology performed increased multiplicatively in WPdv (decrease in water production) and WPRdv (decrease in water production rate) when the TDSI of the mixed water demanded by the user was low. When FD and GD are combined to desalinate salt water, lowering the freezing temperature can significantly increase the freshwater yield, breaking the limitation of freezing temperature for FD. Therefore, an automated, energy-saving freeze desalination-gravity desalination device capable of realizing the collection of the product water according to the users' needs was conceptualized. This study provides new ideas and algorithms for accurately assessing the efficiency of water production in the combined desalination of saltwater by FD and GD.

Bio-inspired design of next-generation ultrapermeable membrane systems

Ultrapermeable membranes (UPMs) have the potential of improving water production efficiency. However, operating at high water fluxes will intensify concentration polarization and membrane fouling. Inspired by the V-formation of birds in nature we propose a transformative membrane module that enables a doubled mass transfer coefficient with a moderately increased friction loss coefficient. Moreover, we present a practical technological pathway for the UPM systems to achieve 338% improvement of average water flux and 18% energy savings relative to state-of-the-art seawater desalination plants. The work makes it practical to operate at a high average water flux of 84 L m−2 h−1 with a controlled concentration polarization for the UPM systems. It breaks through the module development bottlenecks for the next-generation UPM systems and has enormous potential application for alleviating water scarcity crisis in the coming decades.

Optimization of a thermoelectric cooler-based system for atmospheric water production in terms of temperature of condensing surface

The extraction of water from the atmosphere is considered as a potential solution to alleviate the problem of water shortages. Therefore, it is crucial to improving the efficiency of water production from atmosphere. In this work, the effect of temperature of the condensing surface below 0 °C on the water productivity of thermoelectric water generator (TWG) has been studied for the first time. The experimental results indicate that the average water productivity increases with the decrease of the condensing fin surface temperature and there is a maximum increase of 186 % in the average water productivity of TWG when the temperature of condensing fin surface decreases from 5 °C to −10 °C, which is due to the increased temperature difference and the enhanced thermal conductivity of the ice layer. When the form of condensation on the surface of condensing fins is changed from condensing to frosting, the water productivity is increased by 22.1 % at maximum, which can be attributed to the higher thermal conductivity of ice than water. The effect of the sampling time on average water productivity of TWG has also been studied. With the increase of sampling time (0.5 h–3.5 h), the average water productivity of the device gradually decreases by 30.3 %. And the highest average productivity of TWG has been observed at a sampling time of 0.5 h. In addition, the effects of flow rate of water in water block heat exchanger, air flow rate of the cooling fan, voltage of TEC on water productivity are experimentally investigated as well. This study provides a strong theoretical foundation for enhancing the water productivity from humid air.

Desalination performance evaluation of a solar still enhanced by thermoelectric modules

Water scarcity is a pressing global issue, as a significant portion of the world's water resources remain salty and unsuitable for human consumption. Solar desalination has emerged as a sustainable solution to address this challenge, utilizing solar energy for water decontamination and purification. This study explores the enhancement of solar stills through the integration of thermoelectric (TE) modules, focusing on their impact on desalination performance. The optimal saltwater levels, TE module performance, and the efficiency of the system are identified in this investigation. The results of this study reveal that the integration of TE unit into solar still systems leads to a substantial increase in water production, achieving an impressive 35% improvement in productivity compared to conventional solar stills. The TE modules act as efficient cooling agents, accelerating the condensation process within the system. This improvement has substantial implications for addressing water scarcity in arid regions and providing an eco-friendly solution for freshwater production. By harnessing solar energy and advanced TE technology, the findings of this study underscore the potential of TE-enhanced solar desalination systems in providing sustainable and reliable sources of fresh water, even in areas with limited access to traditional water resources. The successful integration of TE modules into solar stills suggests a promising avenue for future research and development. Further exploration of these systems, optimization of TE module parameters, and increased utilization of renewable energy sources are all steps that can be taken to improve water production efficiency and contribute to water resource sustainability.

Sensor-based precision nutrient and irrigation management enhances the physiological performance, water productivity, and yield of soybean under system of crop intensification.

Sensor-based decision tools provide a quick assessment of nutritional and physiological health status of crop, thereby enhancing the crop productivity. Therefore, a 2-year field study was undertaken with precision nutrient and irrigation management under system of crop intensification (SCI) to understand the applicability of sensor-based decision tools in improving the physiological performance, water productivity, and seed yield of soybean crop. The experiment consisted of three irrigation regimes [I1: standard flood irrigation at 50% depletion of available soil moisture (DASM) (FI), I2: sprinkler irrigation at 80% ETC (crop evapo-transpiration) (Spr 80% ETC), and I3: sprinkler irrigation at 60% ETC (Spr 60% ETC)] assigned in main plots, with five precision nutrient management (PNM) practices{PNM1-[SCI protocol], PNM2-[RDF, recommended dose of fertilizer: basal dose incorporated (50% N, full dose of P and K)], PNM3-[RDF: basal dose point placement (BDP) (50% N, full dose of P and K)], PNM4-[75% RDF: BDP (50% N, full dose of P and K)] and PNM5-[50% RDF: BDP (50% N, full P and K)]} assigned in sub-plots using a split-plot design with three replications. The remaining 50% N was top-dressed through SPAD assistance for all the PNM practices. Results showed that the adoption of Spr 80% ETC resulted in an increment of 25.6%, 17.6%, 35.4%, and 17.5% in net-photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO2 concentration (Ci), respectively, over FI. Among PNM plots, adoption of PNM3 resulted in a significant (p=0.05) improvement in photosynthetic characters like Pn (15.69 µ mol CO2 m-2 s-1), Tr (7.03m mol H2O m-2 s-1), Gs (0.175 µmol CO2 mol-1 year-1), and Ci (271.7mol H2O m2 s-1). Enhancement in SPAD (27% and 30%) and normalized difference vegetation index (NDVI) (42% and 52%) values were observed with nitrogen (N) top dressing through SPAD-guided nutrient management, helped enhance crop growth indices, coupled with better dry matter partitioning and interception of sunlight. Canopy temperature depression (CTD) in soybean reduced by 3.09-4.66°C due to adoption of sprinkler irrigation. Likewise, Spr 60% ETc recorded highest irrigation water productivity (1.08kg ha-1 m-3). However, economic water productivity (27.5 INR ha-1 m-3) and water-use efficiency (7.6kg ha-1 mm-1 day-1) of soybean got enhanced under Spr 80% ETc over conventional cultivation. Multiple correlation and PCA showed a positive correlation between physiological, growth, and yield parameters of soybean. Concurrently, the adoption of Spr 80% ETC with PNM3 recorded significantly higher grain yield (2.63t ha-1) and biological yield (8.37t ha-1) over other combinations. Thus, the performance of SCI protocols under sprinkler irrigation was found to be superior over conventional practices. Hence, integrating SCI with sensor-based precision nutrient and irrigation management could be a viable option for enhancing the crop productivity and enhance the resource-use efficiency in soybean under similar agro-ecological regions.

Strategic Decision-Making in Sustainable Water Management Using Demand Analysis and the Water Evaluation and Planning Model

Water infrastructure management relies on information, communication strategies, and affordable technologies. This paper used demand analysis and modeling to guide strategic decision-making in sustainable water management for the urban cluster in Tlemcen, Algeria. To achieve this, the water supply and demand of the study area were assessed over the past three decades. The Water Evaluation and Planning (WEAP) system was employed considering different future scenarios to help decision-makers consider the best choices for sustainable urban water resources management. The results showed that the average water production and distribution efficiency was only 46% due to the high network loss. Therefore, urgent action should be considered to increase the efficiency of the distribution network. Moreover, the outcome showed severe unmet demand in 2050, which can be managed by improving the water networks, increasing conventional water production, and reducing personal water consumption. In cooperation with key stakeholders, new scenarios can be analyzed to develop efficient water management policies and to implement sustainable water allocation approaches.

Optimising water and nitrogen management for greenhouse tomatoes in Northeast China using EWM−TOPSIS−AISM model

Unreasonable irrigation and nitrogen application reduce tomato yield and waste resources. This study explored the effects of water conservation and nitrogen reduction on tomato yield, dry matter, quality, water productivity and nitrogen use efficiency in Northeast China. Experiments were conducted during 2020 and 2021 at three irrigation levels (85–95 %, 75–85 %, and 65–75 % θFC) and three nitrogen application levels (120, 180, and 240 kg hm−2). The optimal water and nitrogen supply patterns were obtained by establishing a newly evaluated Entropy Weight Method−Technique for Order Preference by Similarity to Ideal Solution−Adversarial Interpretive Structure Model (EWM−TOPSIS−AISM). The results showed that the amount of irrigation and nitrogen application significantly affected tomato quality (P ≤ 0.5). Proper deficit irrigation improved tomato quality. Reducing the nitrogen application rate improved nitrogen use efficiency but decreased the tomato yield. Increasing the amount of irrigation increased tomato yield and nitrogen use efficiency. Tomato yield was negatively correlated with water productivity (R= −0.25 in 2020 and R= −0.37 in 2021) and nitrogen use efficiency (R= −0.30 in 2020 and R= −0.20 in 2021). The evaluation results showed that the best water and nitrogen supply mode for our experiment was irrigation at 75–85 % θFC and nitrogen application rate of 180 kg hm−2. The study could promote the sustainable production of greenhouse tomatoes in Northeast China.

Effect of permeable spacer structure on energy loss and mass transfer in reverse osmosis membrane modules

This study used numerical simulation to investigate the effects of a novel permeable cylindrical-flow distributor on energy loss and mass transfer in reverse osmosis (RO) membrane modules. The analysis focused on variables, such as Reynolds number, inlet concentration and flow incidence angle, influencing the improvement of water production efficiency in RO membranes and the reduction of concentration polarisation on the membrane surface. The membrane surface shear stress, vorticity, permeate flux and concentration polarisation factor were used to describe these effects. To better explain the performance of the permeable flow distributor, the viscous resistance coefficient (Du) in the porous media model was used to measure the permeability of the flow distributor. Furthermore, a produced water energy consumption factor (JCP) was defined to represent the energy required for unit water production. The results indicate that the permeable flow distributor significantly reduces pressure loss in the membrane channels, avoiding the high energy consumption associated with traditional flow distributors in RO processes. The Du exhibits an optimal value in the range of 1e8 to 1e10, which maximises the JCP, leading to a 32.9 % improvement compared to traditional impermeable flow distributors. This achievement enables energy-efficient and effective desalination of seawater.

Crop acreage planning for economy- resource- efficiency coordination: Grey information entropy based uncertain model

Reasonable adjustment of crop acreage can improve the sustainability of agriculture in arid zones by promoting economic development, alleviating water scarcity, and improving resource utilization efficiency but meets the challenges of various decision-maker preferences and uncertainties. With the objectives of maximizing economic benefits, minimizing evapotranspiration, and maximizing water productivity and water production efficiency, this study developed a grey entropy based multi-objective fuzzy constraint interval programming model (GEMOFCIP) through incorporation of information entropy technology, fuzzy constraints and interval programming approaches within a general optimization framework. The model is capable of (1) generating the crop acreage management schemes through trading off the different development goals; (2) dealing with the structure and parameter uncertainties of the optimization model; (3) measuring the relative importance of multiple objectives by the introduction of information entropy with the insufficient decision-maker’s preference information. Taking the crop acreage planning problem in Liangzhou, northwest China as a case study, the model was solved under different water-saving and satisfaction degree scenarios. It turned out that, after optimization, the economic benefit, water productivity and water production efficiency have been significantly improved, while the total ET and the total irrigation water have been significantly compressed in the study area. The GEMOFCIP model is superior to the previous models in that it takes into account the randomness of the relative importance of system objective, the vagueness of system constraints and the fluctuations of system coefficients, which would make the model more reasonable, stable and objective. Optimal results can help manage crop pattern with the economy-resource-efficiency consideration and accelerate the healthy development of agriculture in arid zones.

Integrated application of fertilization and reduced irrigation improved maize (Zea mays L.) yield, crop water productivity and nitrogen use efficiency in a semi-arid region

Water scarcity as well as soil degradation and environmental problems potentially caused by excessive application of chemical fertilizers are major challenges to agricultural production in semi-arid areas. It is crucial to explore a suitable and eco-friendly strategy to achieve sustainable production of maize with high crop water productivity and nitrogen use efficiency. Here, a two-year field experiment with three irrigation levels of W1 (220 mm), W2 (140 mm) and W3 (60 mm), and five fertilization types of no fertilizer (CK), chemical fertilizer (CF), bio-fertilizer combined with CF (CFB), organic fertilizer combined with 70% CF (CFO) and bio-fertilizer combined with CFO (CFOB) was conducted to investigate the effect on dry matter, N uptake and remobilization, grain yield, crop water productivity, nitrogen use efficiency and economic benefits of maize in 2021 and 2022. The results showed that the W2 and W3 decreased in the leaf area index, photosynthetic rate, dry matter accumulation, the maximum dry matter accumulation rate and actual crop evapotranspiration. Under W1 condition, the CFB improved the growth of maize, increased the dry matter and nitrogen accumulation and yield, with 8.1% and 7.4% higher than CF in 2021 and 2022, respectively. Under deficit irrigation (W2 and W3), CFOB significantly increased the leaf area index, photosynthetic rate, dry matter accumulation at later growth stage, in addition, CFOB increased the post-silking N uptake and the percentage in total N content, finally improved the grain yield with 23.8% and 22.8% under W2, 22.5% and 25.7% under W3 higher than that of the CF in 2021 and 2022, respectively. Irrigation and fertilizer showed a coupling effect on grain yield, crop water productivity, agronomy efficiency and nitrogen use efficiency. Overall, the CFOB under moderate deficit (W2) exhibited the highest water productivity, nitrogen use efficiency and economic benefits, as well as maintained the high yield, could be a promising approach to sustainable development of local maize.