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