Modelling Treated Laundry Greywater Reuse for Irrigation Using an Affordable Treatment Method and Seed Germination Test
Camila C. A. Cardoso, Ildikó Bodnár
Abstract
A potential solution in areas facing water shortages is greywater (GW) reuse. GW is produced in bathrooms, laundry rooms, and kitchens of households. With proper treatment, it can be an alternative source for the agriculture sector, which consumes approximately 70% of the world’s water. This paper represents the characterization of synthetic laundry GW fraction (LGW), its treatment and modelling of treated LGW reuse for irrigation using a seed germination test. LGW’s constant quality (pH = 8.0 ± 0.3, turbidity = 174 ± 73 NTU, BOD5 = 300 ± 60 mgL−1, TOC = 162 ± 40 mgL−1) is suitable for testing the treatment method’s efficiency. Coagulation–flocculation, applying iron(III) chloride and sand filtration as a simple treatment combination, generates good-quality irrigation water (pH = 7.27 ± 0.23, turbidity = 0.6 ± 0.4 NTU, BOD5 = 17 ± 8 mgL−1, TOC = 16 ± 6 mgL−1). Seed germination tests with different waters, and elemental analysis of water, roots, and stems of the plants were done to verify the plants’ quality. The sodium adsorption ratio (SAR) for the raw LGW (SAR = 4.06) was above the threshold (<3) for safe irrigation, thus it is not recommended for this purpose. Based on the elemental analysis results and SAR value of treated LGW (SAR = 2.84), it can potentially be used for irrigation purposes.