Fostering product innovation for water saving, treatment and reuse in household appliances: towards green washing solutions

Household appliances such as clothes washing and dishwashing machines use 10 to 30% of total domestic water consumption. Currently available washing machines do not provide systems to store and reuse wash and rinse water, or to filter dirt and residual detergents from drain water, or to monitor water quality to detect residual substances. This paper provides results of a three-year research project to develop advanced technologies to recycle waste water and reduce water and energy used by clothes washing machines. The project goal is to reduce energy and water consumption by 25% to 30%. To reach this goal three complementary technologies were investigated and demonstrated: (1) mechanical water filtration; (2) Advanced Oxidation Processes (AOP) for purification/sanitation, and (3) water quality monitoring devices to detect whether substances or residuals are present. A “modular” approach was applied so each solution can be implemented separately or incrementally. Water filtration tests showed positive results with polymeric filters. AOP-based methodologies were effective in chemical oxygen demand (COD) reduction and in degradation of anionic surfactants and nonionic surfactants. Ozone and UV can also be used as anti-microbial agents. Water quality monitoring of COD and its correlation to water conductivity enables different water reuse algorithms (cycles). All technologies were tested separately demonstrating the possibility of a modular approach for the final implementation. Results for clothes washers can be applied to other appliances such as dishwashers. These results provide important data for designing a dedicated “green washing” system