Waste design for households with respect to water, organics and nutrients

Waste design couples handling and treatment of waste with the production and control of waste materials. This integrated approach will allow for a reduced use of non renewable resources in waste treatment. The paper discusses the use of waste design for households and its impact on the composition of household wastewater. This will allow for the design of a wastewater with characteristics quite different from those normally found. The separation of toilet wastes or just urine can reduce the amount of nitrogen and phosphorus in the wastewater to a level where no further nutrient removal is needed. The BOD and COD load to wastewater can be significantly reduced by separating toilet wastes and part of the kitchen wastes. The phosphate content of detergents influences the phosphorus load significantly. Kitchen wastes can be diverted to the solid waste system or the compostable fraction of solid wastes can be incorporated into the wastewater by use of garbage grinders. The change in pollutant load can be achieved separately or in combination with water savings. It is thus possible to reduce or increase the overall concentration of pollutants, and to design wastewater with a given COD/TN or COD/TP ratio, which is of significant influence on biological nutrient removal processes.