The removal of pollutants from synthetic bathroom greywater by coagulation-flocculation and filtration as a fit-for-purpose method

Abstract

It has been demonstrated that treated bathroom greywater (TBGW) is a useful substitute for fresh water for non-potable applications in households. Reuse of TBGW for irrigation, toilet flushing, car washing etc. offers a good opportunity to save drinking water and meet the sustainable development goals (SDGs). In this study, synthetic bathroom greywater (SBGW) was compiled in a controlled manner and used as a substitute for bathroom GW. Detailed statistical analysis also was performed to confirm the similarity between real and synthetic BGWs. SBGW is suitable for testing efficiency of applied treatment methods. It was confirmed that coagulation–flocculation with iron(III) chloride and sand filtration was the most effective method of the tested 7 systems. The best and affordable treatment combination generates good-quality treated SBGW (TSBGW) (pH = 7.54 ± 0.29, TURB = 0.54 ± 0.49 NTU, BOD₅ = 21 ± 10 mgL⁻¹, COD = 32 ± 11 mgL⁻¹, and TOC = 12.7 ± 6.7 mgL⁻¹) for different non-potable purposes by complying with the regulated limit values for reuse. The elemental analysis of raw, TSBGW and tap water (TW) samples by MP-AES method provided further support for safe recycling. This study leads to the conclusion that the generation of TBGW by fit-for-purpose treatment can effectively meet the circular economy goals at household level. The recycling of GW is of limited importance in the European Union (EU) and legal regulations are not available in many countries. This study provides novel support for regulating the reuse of water in Eastern European countries.