Pollution and water quality index of boreholes within unlined waste dumpsite in Nnewi, Nigeria

Abstract

Borehole water has been the main source of drinking water for the communities living within the Nnewi metropolis. The quality of this borehole water has been significantly affected by the presence of unlined waste dumpsites which release leachates. The present study investigated the physicochemical characteristics and quality of borehole water located around the environment of the unlined dumpsite in Nnewi. In this study, thirty-two (32) borehole water samples were collected from around the dumpsite (16) and control (16) areas in wet and dry seasons. The levels of the physicochemical parameters were determined using the American Public Health Association (APHA) standard methods. The quality of the borehole water was compared with World Health Organization (WHO) permissible drinking water limits. The pollution index (PI) and water quality index (WQI) of the borehole water were also evaluated. The results also showed that only the nitrite values in the dumpsite area for both seasons were above the WHO drinking water limits. The summation of the pollution indices were above the critical value of 1 in both seasons for the study areas. The WQI revealed that the water samples were heavily polluted with the most polluted being the dumpsite area in both seasons. The results revealed that the underground water in the dumpsite area was contaminated through the uncontrolled release of leachates from dumpsite. The contamination from the control area may not be related to the dumpsite but was linked to irregular waste disposal sites, wastewater infiltration and run-off from farmlands. The borehole water samples was not good for drinking and domestic purposes without proper treatment.