4TH International Congress on Technology - Engineering & SCIENCE - Kuala Lumpur - Malaysia (2017-08-05)

Biological And Electrochemical Wastewater Treatment In Decentralized Facilities Designed For Use In The Developing World

The Hoffmann research group at Caltech with support from the Bill and Melinda Gates Foundation has developed, tested, and implemented transportable reactor systems that have been designed for the onsite treatment of domestic wastewater. After pre-treatment with a sequential anaerobic/aerobic baffled bioreactor, the effluent is processed sequentially through semiconductor electrochemical arrays where the COD and microbial loads are reduced to below US EPA reuse standards. Special mini-reactors are used to convert the treated wastewater to handwashing and drinking water standards. The treated black water is recycled into a flush water reservoirs without discharge to the surrounding environment. Human wastewater can be clarified with the elimination of suspended particles along with >95% reduction in chemical oxygen demand (COD), and a total elimination of fecal coliforms, E. coli, viruses, and total coliforms. Enteric organism disinfection is achieved for bacteria and viruses via anodic reactive chlorine generation from in situ chloride coupled with cathodic reduction of water to form hydrogen. Improvement of the performance and durability of the core semiconductor anodes along with materials modifications to lower their production costs ongoing. Second-and third-generation prototypes are undergoing field-testing in locations that lack conventional urban infrastructure for wastewater discharge and treatment; the packaged treatment systems can operate without an external source of electricity or fresh water. Manufacturing and extensive field-testing in China is underway. Two Caltech-China joint-venture companies, Eco-San and Entrustech, have been established in Yixing, China to manufacture solar units for the developing world and electrochemical reactor systems, while at the same time additional industrial collaborations have been established in India with ERAM Scientific and with the Kohler Company (USA/India) for production of units to be used in urban and peri-urban environments in India. At the current time, larger-scale units are assembed for use in South Africa, Peru, Southern China, and Cambodia.
Michael Hoffmann