Detergents as a Source of Phosphorus in Sewage: the Current Situation in Brazil

The domestic use of powder detergents designed for cleaning fabrics may contribute to the phosphorus input in sewage. Hence, the regulation of the use of phosphorus in these products is considered a measure that can improve water quality, in addition to contributing to the preservation of nutrient reserves and promoting the reduction of costs involved in the implementation, operation, and maintenance of sewage systems. To evaluate the contribution of detergents in the total amount of phosphorus present in the wastewater based on the current scenario experienced in Brazil, analyses were performed in the tributary wastewater in three wastewater treatment plants (WWTPs) situated in different regions of the state of São Paulo, Brazil, as well as the analysis of 30 samples of detergents sold in the national territory. We verified that the products currently sold in the country have low concentration of phosphorus, up to 0.01 % by weight. Thus, the contribution of detergents to the total amount of phosphorus present in the wastewater of the studied WWTPs is fairly low, in the range of 0.0014 g/inh.day. Such contribution corresponds to about 0.17 % of the total amount of phosphorus present in the wastewater. Results show that it is necessary to revise and to reduce the values stipulated by existing legislation in order to regulate the operating conditions currently practiced by the productive sector and to provide the maintenance of this relevant source of phosphorus in sewage under control.