Recipient Organization
SOLMEM LLC
101 PARKLAND BLVD STE 103
SUGAR LAND,TX 774785521
Performing Department
(N/A)
Non Technical Summary
Water is critical to agriculture production and food security. According to data from the World Bank, trrigated agriculture represents approximately 20% of total cultivated land, and accounts for 40% of the total food produced worldwide. The demand for irrigation water is predicted to increase greatly as a 70% increase in agricultural food production is needed to meet the demand of the growing population. At the same time, competition for water with municipal, environmental and industrial users will continue to increase, with 25 - 40% of agriculture water expected to be re-allocated to other sectors. These changes will lead to further increase in the already large gap between the irrigation water demand and supply. In the meantime, agriculture is facing increasing water risk as a result of global climate change, which increases the uncertainty in precipitation patterns and therefore agriculture water supply. Extended droughts have had overwhelming impacts on global agriculture production, and will be exacerbated by global climate change. Finding alternative water sources for agriculture is therefore necessary to sustain agriculture activities and ensure food security.On the other hand, agriculture activities are a major contributor to challenges associated with water resources, in both water quantity and quality. Agriculture irrigation accounts for ~ 70% of freshwater withdrawal. Intensive pumping of groundwater for agriculture has led to depletion of drinking water aquifers in many places. The use of large quantities of fertilizers, pesticides and herbicides leads to contamination of surface water by surface runoff or discharge of irrigation drainage water. Salts in water do not degrade, and can accumulate in water basins and agricultural lands. Increasing salinity in irrigation water reduces crop productivity. More importantly, accumulation of salts in soil will eventually remove land from production, leading to loss of agricultural land. In California alone, 4.5 million acres of irrigated cropland are affected by saline soils or saline irrigation water, putting tens of thousands of acres of productive agricultural land at risk.Treating unconventional water sources at low costs and using them for agriculture irrigation present an excellent solution to irrigation water supply. When using wastewater (e.g., irrigation drainage water, oil&gas produced water) as the water source, the treatment and reuse of the waste streams not only eradicate the need for wastewater disposal, but also create additional, high quality irrigation water supply. Therefore, treatment and reuse of agriculture wastewater for irrigation and other agriculture applications is particularly attractive as it reduces the impact of agriculture on water quality while reducing freshwater use. Currently, irrigation drainage is either discharged into surface water, or collected in large evaporation ponds, both causing a myriad of environmental problems.One important challenge in the treatment of these alternative water sources is the need to remove salts, i.e., desalination, which is highly energy intensive and expensive if using existing technologies. Irrigation using alternative water sources will only be a viable solution if the energy consumption and total costs for desalination of the various alternative irrigation water sources can be greatly reduced. SolMem's SolarMEMD technology can desalinate saline streams with a wide range of total dissolved solids (TDS) such as irrigation drainage water highly efficiently, using sunlight as the energy source. Its low electrical energy consumption and low capital costs result in a levelized cost of water significantly lower than existing treatment technologies, making it economically feasible to utilize locally available alternative water sources for agriculture irrigation.Solar desalination can help solve water shortages in a sustainable manner, while minimizing contamination in water management and food production. In summary, our technology brings the following benifits:1) It can improve farming activity and profitability by improving the quality of soil and irrigation water. Accumulation of salts in irrigation water and soil is a serious problem threatening productivity of irrigated agriculture in many areas in the US. The SolarMEMD process effectively removes total dissolved solids (TDS) or salinity, as well as other contaminants (e.g., arsenic, selenate and boron) from irrigation drainage water or other alternative irrigation water sources using solar energy. This can prevent salts in the irrigation water from accumulating in soil or contaminating surface water in agricultural areas through discharge of irrigation drainage water, making it an economically feasible solution to farmland salt management. It also keeps other contaminants below toxic thresholds for high crop production and prevents contaminant accumulation through the food chain. 2) It equips farmers as well as local and regional water agencies with a cost-effective method to combat severe droughts by enabling reuse of irrigation drainage water and other alternative water sources at a low cost using renewable energy. This will greatly reduce the uncertainty in farm productivity caused by increasingly unpredictable precipitation patterns resulting from global climate change. 3) Implementation of the SolarMEMD technology can reduce the environmental impact of agriculture by reducing its water footprint and lowering the load of contaminants in agricultural runoff. Using alternative water sources reduces freshwater withdrawal for agriculture, the largest water user among all sectors. This helps relieve water resource-related conflicts in water stressed areas. Treatment and reuse of irrigation drainage water and surface runoff also reduces the discharge of contaminants, e.g., fertilizers, pesticides, and herbicides into surface water bodies, and eliminates the need for large evaporation ponds, avoiding their negative environmental impacts (e.g., harm to waterfowls) while reclaiming the lands used for farming.
Animal Health Component
33%
Research Effort Categories
Basic
33%
Applied
33%
Developmental
34%
Goals / Objectives
Ensuring water supply for agriculture irrigation and properly managing irrigation drainage are great challenges in regions with significant irrigated agriculture. Cost-effective treatment and reuse of irrigation drainage and other alterantive water sources (e.g., brackish groundwater, industrial wastewater) for irrigation are needed to enhance water and food security, to control salinity accumulation, to minimize surface water contamination and potential harm to wildlife, and to alleviate local and regional water stress.Building upon the success of our Phase I research on the proof of concept of a novel solar multi-effect membrane distillation (SolarMEMD) system, this SBIR phase II project aims to advance SolarMEMD from the current technology readiness level 3 (TRL3) to TRL7, and to validate its commercial potential. The project team will construct and prototype a pilot scale SolarMEMD system and assess its performance in treating irrigation drainage and other alternative irrigation water sources. Out technical objectives include: 1) determining the optimal design of the SolarMEMD membrane module for maximizing GOR and specific water production rate; 2) quantifying the impact of solar concentration on SolarMEMD performance and cost; 3) identifying potential operating challenges associated with membrane fouling and scaling in long term operation; 4) developing thermal storage strategies for night operation; 5) determining how to couple the SolarMEMD with low pressure RO/NF to create synergy and further lower cost for source waters with relatively low TDS. The proposed Phase II research is expected to validate the SolarMEMD technoloy for agriculture irrigation drainage treatment reuse, a critical milestone in our commercialization plan.
Project Methods
(I). Design, construct and optimize a spiral wound SolarMEMD moduleWe will first design, construct and optimize a pilot-scale SolarMEMD module. In our post-Phase I research, we have constructed a small SolarMEMD module (Fig. 6a). This module design has separate feed inlet and brine outlet for the 1st effect and the rest of the effects, allowing independent control of the feed flow rate in the 1st effect. This is important as the optimal flow rate for the 1st effect, which also serves as the solarthermal collector, is anticipated to be very different from those for the other effects. We will first test the small module in lab experiments to answer the following questions:1) What is the optimal number of effects for a given solar concentration ratio?2) What is the impact of flow distribution and solar irradiance distribution on membrane module performance?3) What are the minimum material specs for the different components of the module?4) What is the impact of hydraulic condition in each flow channel?(II).Couple the SolarMEMD module with a solar concentrating deviceWe will evaluate two types of PTC: one with a high solar concentrating ratio (CR) of 15, and the other with a low CR of 2. It is important to note that the optimal number of effects depends on the CR as the higher energy input at higher CR can drive more effects. Therefore, each PTC will be tested using a different membrane module that is optimized for the specific CR.To ensure uniform distribution of the concentrated sunlight on the entire exterior surface of the photothermal membrane, we will test a mechanical mechanism that rotates the SolarMEMD membrane reactor at low rate. Other design considerations, e.g., the support of the membrane reactor on the PTC, thermal shields to protect dry components of the membrane module from concentrated sunlight, casing for tubings/pipes, will also be tested in this task.(III).Design and build a pilot-scale SolarMEMD prototype systemWe will build a protoype in this project. The prototype system will have a design capacity of 150 - 200 L clean water production per day with a target water recovery of 50 - 95% depending on feed water TDS. Pretreatment processes will be included to remove particulate matter and to control microbial growth. Thermal storage strategies will be evaluated via model simulation (IV) and the most efficient to support night operation will be included in the prototype system design. Monitoring devices will be included to collect temperature, TDS/conductivity, flow rate, pressure (vacuum), tank water levels data throughout the system, which will be used for automatic control of the system. A cleaning in place (CIP) system will be included to mitigate membrane scaling, fouling, and wetting. In addition, sampling ports will be installed on the feed, permeate, and brine lines for water sample collection. The system will be able to automatically shut down in case of equipment failure or upon detection of other operation abnormality. The pilot system will include indoor and outdoor subsystems. The outdoor subsystem includes the SolarMEMD module coupled with a PTC, while the indoor subsystem includes a pretreatment train, RO membranes, control and power stations, and a thermal storage tank for night-time operation. A 20 ft cargo container with proper insulation and ceiling would be used to house the indoor subsystem.(IV).Model simulation of coupled heat and mass transfer in the SolarMEMD processConsidering the complex 3-D flow and temperature fields in the spiral wound module, our multi-effect model will adopt a planar configuration with decreasing area at higher stagesto represent flow channels in the spiral wound configuration. The single-effect model will be applied to each effect, while additional boundary conditions are applied to account for the hydraulic and thermal coupling between effects. The SolarMEMD model will then be calibrated and validated using experimental data collected from our lab-scale module.(V).Pilot-scale testing of the SolarMEMD systemAs a baseline, the system will be operated during the daytime for 8-12 hours. We will evaluate the thermal storage strategy identified in IVfor nighttime operation. The hours of operation after sunset depending on the volume, TDS and thermal energy content of the water stored inside the thermal storage tank (if feed water or brine is chosen as the thermal storage medium). Parameters relevant to system performance including temperature and pressure at subsystems inlets and outlets, flow rates, water production rate, chemical consumption, water recovery, and permeate flux as well as brine quality (TDS, conductivity, and UV/VIS absorbance) will be continuously monitored. Environmental conditions such as ambient solar irradiation, temperature, and humidity will also be recorded. Furthermore, the energy consumption of the pumps and compressors will be monitored. In addition, water samples will be collected from sampling ports throughout the system and analyzed for relevant water quality parameters including total organic carbon, specific contaminants of concern (e.g. Arsenic, Selenium, and Boron), and major fouling and scaling species (e.g., Ca+2, Mg+2, SO4-2, CO3-2, Fe(II)/Fe(III), dissolved silica) to investigate contaminant removal efficiency and fouling and scaling of the membranes. Pumping energy consumption will be tracked. The performance data will be used to assess the operation and maintenance cost of the integrated system including chemical and energy consumption, pretreatment requirement, and membrane replacement cost.(VI).Techno-economic analysiswe will perform TEA using data obtained from our pilot study, which will be based on optimized membrane module and system designs. As shown in the Phase I study, the performance and hence cost of the SolarMEMD system depend strongly on the operating and environmental conditions (e.g., feed water TDS, solar irradiance, ambient temperature). We will use the TEA model to optimize operating conditions to minimize LCOW using the specific environmental conditions of our test site. In addition, TEA analyses will be performed using representative environmental conditions in regions where SolMem's target markets are located (e.g., California, Colorado, Texas) to determine suitability of the technology for different geographic locations. We will adopt the cost assumptions (e.g., interest rate, electrical energy cost, etc.) used by DOE's economic evaluation of solarthermal desalination assumptions. The LCOW will be broken down into capital (CAPEX) and operating and maintenance costs (OPEX). Contribution from different system components (e.g., PTC and membrane module) and individual processes (e.g., pretreatment, chemical cleaning, etc.) will also be analyzed to identify major cost contributors and places where the large cost reduction can be achieved by further R&D.