Optimal Detergent Concentration in Greywater for Plant Growth using a Mung Bean Model

Abstract

Greywater is lightly used non-toilet water (e.g. bathwater) that can be reused to irrigate plants. The reuse of greywater is receiving increasing global attention as many cities are trying to conserve freshwater resources amid changing climates and extended dry seasons. Here, we aim to understand how greywater affects plant growth using a mung bean model. We hypothesize that mung bean sprout length will be affected by greywater irrigation. We grew mung beans using different solutions of greywater (1% , 0.1%, 0.01%, 0.001%, 0.0001%) and recorded the sprout length after five days. We conducted a one-way ANOVA analysis and a post-hoc Tukey’s test for our data analysis. The data analysis demonstrates that the mean sprout length was significantly different between the 1% and 0.0001% treatments, as well as between the 1% and 0.001% treatment groups, with a p-value of 0.00186. We conclude that greywater affects plant growth, where 0.0001% and 0.001% greywater solutions yielded the longest bean sprouts, whereas 1% yielded the shortest bean sprouts. This difference in plant growth can be attributed to surfactant concentrations, where low concentrations nourish plants but high concentrations of surfactant inhibit plant growth.