Analysis of domestic wastewater recycling methods for agricultural and irrigation uses using combined SWOT-QSPM model, Case study: Sabzevar city Treatment Plant

Sewage produced in homes can be divided into two groups. The sewage produced from domestic uses such as bathing and laundry and dishwashing water is called gray water and the sewage produced from toilets is called black water. In many systems used in the world, gray water is combined with black water and discharged by the municipal sewage system. However, gray water has a higher quality due to its lower pollution content and has a higher potential for reuse. In this study, using the combined model of SWOT analysis and QSPM matrix, the do's and don'ts of using the effluent from the Sabzevar city treatment plant were investigated. Based on the results of experiments on the effluent, the use of this effluent for agriculture demands further disinfections due to the Coliform density outside the permitted range which is recommended in national and international standards. However, in general and in most of the years, the quality of the effluent of Sabzevar municipal wastewater Treatment Plant is within the permissible limits and it can be used for irrigation of industrial and fodder plants which is not used directly by humans or for urban landscape according to the results obtained from the study of chemical and microbial quality of effluent (TDS, Nitrate, Nitrite, EC, parasite eggs). Considering that public opinion on the use of wastewater is somewhat negative, we should seek to create a positive culture by holding events at the level of councils, villages and rural people. In addition, due to the desert nature of the area, the effluent can be used for biological regeneration and planting plants such as Nitraria and Haloxylon, and species such as Atriplex. Also, due to the existence of factories such as washing plants and cement factories in the region and the reasonable price of effluents and water saving, the conditions of using effluents in such factories can be studied and researched.