Greywater Characteristics and Treatment Processes: A Review

Abstract

Treatment of greywater has become justifiable to fulfil the increasing demand of fresh water and environment protection. The availability of water has reduced from 1299 m3 per capita in 1996-97 to 1100 m3 per capita in 2006 and it is expected to less than 700 m3 per capita in 2025. The worldwide population is projected to surpass nine billion by 2050 and total water consumption of urban will surge by 62% from 1995. Water used in clothes washing produce approximately 25-35%, kitchen 11 %, bath tubes 48 % and hand wash 7 % of greywater. Therefore, there is a dire need of treatment of greywater. The different technologies which are used in the treatment of greywater may be classified as physical separation techniques, biological treatments and chemical or advance oxidation processes (AOPs). In chemical treatments there are different processes such as chemical and electrocoagulation. The percentage removal efficiency of chemical coagulation for BOD, COD, Turbidity is 88.78 %, 63.72 % and 90.88 % respectively. Chemical coagulation can also remove bacteria, microbial pollutants and total organic carbon.