Non Technical Summary
Most of the world's freshwater usage--as high as 70%--goes to agriculture. Unfortunately, in many of the country's major farming regions secure sources of agriculture water are threatened: freshwater aquifers are being over pumped, coastal saltwater intrusion is tainting freshwater supplies, agricultural run-off is dumping nitrates into the environment, and severe droughts are periodically interrupting supplies. And, although may farm regions have large underground reserves of brackish water, the mineral content of this water cannot be tolerated by most crops.The proposed work will convert the country's large brackish water reserves into an agricultural water resource by overcoming the major obstacle to this conversion: the cost and environmental impact of waste brine disposal. In past work, AIL Research has proven a very efficient, thermal distillation process that could convert 90% of a brackish water reserve into agricultural grade water. This conversion also produces a small, but significant, volume of waste brine that has all the minerals originally in the brackish water. In the proposed work, we will prove a modified, patent-pending version of our distillation process that recovers essentially 100% of the water in the waste brine leaving a residue of solid salt crystals that can be much more easily disposed. (Ideally, the solid waste would be sold to a processor that recovers minerals for resale to industry). The economic viability of the new Zero Liquid Discharge (ZLD) will be assessed in the context of proposals for agricultural-grade water that have been submitted to growers by our commercialization partner,

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
133	0210	2020	30%
403	0210	2020	25%
605	0210	3010	20%
402	0210	2020	25%

Knowledge Area
403 - Waste Disposal, Recycling, and Reuse; 133 - Pollution Prevention and Mitigation; 605 - Natural Resource and Environmental Economics; 402 - Engineering Systems and Equipment;

Subject Of Investigation
0210 - Water resources;

Field Of Science
2020 - Engineering; 3010 - Economics;

Goals / Objectives
The primary goal for theproposed work is to greatly expand the country's water resources for agriculture by reducing the disposal costs for the brine produced when inland brackish water is desalted. A novel process for thermally separatingwaste brine into a stream of pure water and solid, landfillable salt will be proven at the laboratory scale. The proposed Zero Liquid Discharge (ZLD) process has the potential tobring brine disposal costs under $150 per acre-foot of produced clean water--which is a cost that thenwill open the country's vast inland brackish groundwater reserves to agriculture.The proposed work will provide the information needed to assess the economic and technical feasibility of the novel ZLD process. Several of the more important objectives for the work are:Prove that the innovative concept underlying the proposed work--i.e., thethermal separation of water from a saturated salt solution with the managed precipitation of salt crystals--can be implemented in a configuration that couldbe scaled up to a commercially viable size.Prove that the kinetics for the process are sufficiently fast to allow the process to be implemented with equipment that is reasonablysized.Propose conceptual designs for the major subsystems of a ZLD separation plant based on the proposed concept.Determine how the efficiency of the seperation process varies with the concentration of Total Dissolved Solids (TDS) of the feed brine.Identify themaintenance needs of a desalination plant based on the proposed ZLD process. Estimatethe service life of the critical components.Identify possible degradation mechanisms for the process, and if they are significant, suggest how they might bereversed,Identify thenear-term and long-term economics for a solar-driven ZLD process based on the proposed concept.Identify the most promising early markets for the proposed concept.Assess the probabilitythat the process could compete in the larger market for seawater desalination

Project Methods
The proposed work will use accepted experimental methods to build and test lab-scale prototypes designed to prove the technical feasibility of the proposed concept. The laboratory work will be supplemented with engineering and economic analytical modeling of conceptual ZLD systems that employ the proposed concept. The analytical work will project the cost for brine disposal over a range of initial brine properties.