The Distributed Low-Energy Wastewater Treatment (DLEWT) project aimed to demonstrate and validate a novel decentralized energy-efficient anaerobic wastewater treatment technology. DLEWT is a distributed low-energy wastewater treatment system that enables water reuse and converts black water chemicals into harvestable fuels, hydrogen, and methane gas, for energy generation. DLEWT integrates an anaerobic membrane bioreactor (AnMBR) process with clinoptilolite ion exchange and ammonia electrolysis for the efficient removal of organics, particulates, and ammonia. Methane, a byproduct of the anaerobic reaction, and hydrogen, from ammonia electrolysis, can be used to generate electricity to offset system energy requirements. Additionally, the availability of treated water for reuse will decrease installation water usage.

The DLEWT project symbiotically integrated technologies to treat wastewater in a manner that reduces energy consumption and generates useful fuels. The AnMBR subsystem degrades organics in wastewater and generates methane starting the treatment process. The clinoptilolite ion exchange subsystem is used to sequester the ammonia from the AnMBR process effluent and create a more concentrated ammonia brine solution. The ammonia brine waste stream created during regeneration of the clinoptilolite media is delivered to the ammonia electrolysis system. The ammonia electrolysis system breaks the ammonia brine solution into a useable hydrogen fuel and nitrogen gas. Overall, the system treats wastewater more energy efficiently than traditional aerobic treatment methods while generating two useable fuels.

AnMBR Side View

Clinoptilolite Columns and Electrolysis

While DLEWT never completely functioned as designed, the subsystems were run independently and assessed. The AnMBR system was run for several months successfully producing methane and ammonia-rich permeate using a synthetic wastewater solution derived from dog food. The design of the clinoptilolite system was sufficient at completely removing the ammonia from the test solutions. Cost assessment models indicates that the implementation of anaerobic digestion combined with the ion exchange and ammonia electrolysis systems leads to an increased net energy balance by 0.46 kWh/m3 compared to conventional activated sludge and by 0.15 kWh/m3 compared to AnMBR with biological nitrogen removal making the DLEWT system a net energy producer.

The DLEWT system was plagued by a variety of implementation issues deriving from multiple sources including controls, mechanical operation, and COVID. The largest challenge with implementing the DLEWT was the robustness of the electrolysis system. In its current state, the system lacks the ruggedness that would make it usable in a commercial application or field demonstration. (Project Completion - 2023) 

 Guy, K. A. and M. Page. 2019. Ammonia Sequestering System. US Patent 10,202,287.