Das NTA-Problem

Abstract

Because of the evident need to reduce the input of Phosphorus to surface waters and the resultant restrictions on the use of phosphates as builders in detergent formulations, the detergent industry turned its attention to substitutes; NTA was considered the best substance. To be acceptable as a substitute builder the substance should have an adequate performance and no undesirable effects should be produced in the environment when the substances are used in large quantities associated with the present scale of detergent use. The behaviour and fate of NTA in the environment with particular reference to the removal of NTA during waste water treatment and the effects of NTA on heavy metal solubility both during treatment and the effects of NTA on heavy metal solubility both during treatment and in the receiving waters have been widely studied. It is concluded that NTA removal during secondary biological treatment is after adaption normally high but is subject to considerable variation both temporal and between works as a result of changes in NTA load, temperature, water hardness and treatment process parameter. If NTA is excessively used the resulting concentrations in surface waters may be sufficient to remobilise heavy metals and contaminate potable waters particularly in areas of low effluent dilution and high water re-use. Therefore the use of NTA as a detergent builder should be limited and the behaviour in the environment carefully monitored.