Sustainable reuse options of treated effluents: a case study from Muscat, Oman

Oman, being a semi-arid country, is in great need for extensive reuse practices of treated wastewater effluents. However, these practices need to be environmentally and economically feasible under the prevailing sophisticated treatment systems, inadequate infrastructure including sewers and wastewater-treatment plants (WWTPs). This study attempts to provide decision makers with a comprehensive characterisation of treated wastewater effluents in Muscat and to assess public opinions towards various reuse options of treated wastewater. Results from characterisation of the treated wastewater indicate great performance of the WWTPs in removing biological oxygen (O₂) demand (BOD) and chemical oxygen demand (COD), as the maximum BOD and COD observed were less than 4 and 60 mg/l, respectively. The turbidity was found very low (below 3 nephelometric turbidity units), including total suspended solids of 13 mg/l. Most of the results showed relatively low counts of the total coliform bacteria except where a high variation was observed (400–2400 most probable number/100 ml). However, the aforementioned water quality indicators were able to meet Omani standards with the exception of a few parameters. In addition, the survey showed that the public had a general understanding of the different options of treated wastewater applications including their treatment procedures.