A simple technique to enhance surface runoff quality for water supply in a Nigerian rural community: a pilot-scale study

Runoff water can be harnessed as a water source to augment water needs, especially in rural communities with agricultural-based economies in developing countries. This study investigates accessible means of water treatment. Surface runoffs were collected during seven different rainfall events in 2019. These were subjected to four treatment levels: storage, filtration, coagulation and adsorption, in the laboratory. Optimal dosages of groundnut (140 mg/l) and inactivated charcoal (1800 mg/l) determined from laboratory jar tests were used as coagulants and adsorbents, respectively, with varied retention times. These were investigated in a 4 by 5 factorial experiment laid out in a randomized complete block design (RCBD) in four replicates. Water quality models were also developed from the mass balance equation and were used to simulate achievable water quality at specified retention times. Turbidity (T), total coliform count (TCC), Escherichia coliform count (ECC), conductivity (C) and nitrate (N) of freshly harvested runoff met the World Health Organization standards for domestic water and irrigation water quality standards for salt-sensitive crops from the 14th day retention time. Average values of T, TCC, ECC, C and N on the 14th day were 0.82 ftu, 0.015 cfu/ml, 0.01 cfu/ml, 274 µΩ/cm and 8.92 mg/l, respectively. Simulated water quality parameters were not significantly different from observed values since p > 0.05. Treated runoff water is a viable resource for both agricultural and domestic purposes. This aligns with the broader objective of advancing the sustainable development goal six, which pertains to clean water and sanitation, and offers a promising solution for regions facing water scarcity.