Evaluation of Hospital Wastewater Treatment and Disposal: The Case of Wolita Soddo Teaching Referral Hospital, Wolaita Zone, Southern Ethiopia

Abstract

Untreated liquid hospital wastes are known sources of several chemicals, remnants of medicine, disinfectants and antineoplastic drugs regarded as perilous for humans and the environment and un-metabolized antibiotics in low concentration that contributes largely to the development of antibiotic resistance in our natural micro-flora or environmental micro-flora. Therefore, issues of improving the management of hospital wastes are receiving increasing attention throughout the world since hospitals generate tons of medical waste each year. Septic tank is a sanitization technology that exclusively treats domestic wastewater. Thus, this study was conducted to examine the adequacy of hospital wastewater treatment and disposal in Wolaita Sodo Teaching Referral Hospital. The physicochemical, heavy metals and bacteriological parameters were investigated by taking appropriate samples from March to July 2015 from 5 sampling points. Both the sampling and analysis of the samples were carried out employing standard methods. The results of nine (9) parameters such as Turbidity, conductivity, Temperature, pH, TDS, TSS, NO₃^-, SO₄^-2 and PO₄^-3 had significant difference between sampling points (p<0.05). On the other hand, the results of BOD₅, COD, DO, Mn, Fe, Cu, Cr, FC and TC were comparable among sampling points(p>0.05). Amongst the physicochemical parameters, the average value of BOD₅ (46.17+20.21mg/l), COD (205+76.48mg/l), TSS (12,788.2+0.78mg/l),), NO₃^- (2492.67+0.1mg/l),TKN (11,422.5mg/l), Fe (0.795+0.01mg/l), Pb (0.042mg/l) were found to be higher than the maximum permissible limit set by Ethiopia Environmental Protection Authority (EEPA, 2003 : USEPA, 2002) while EC (198.08+2.275NScm-), Turbidity (53.25+3.68NTU , TDS (98.84+1.14mg/l) and SO₄^-2 (4+2.18mg/l) were below the maximum permissible level. The mean concentration of all heavy metals except Pb and Fe were lower than the maximum permissible level (USEPA, 2002) for effluent discharged to the environment. Similarly, the mean value of TC (1158.335+515.32MPN/100ml)and FC (1041.67+ 360.85MPN/100ml were higher than the standard set by (EPA, 2002) effluent discharged into the environment. In addition, the removal efficiency of septic tank was evaluated and presented as TSS (67.08%), BOD5 (54.61%), PO4-3 (33.68%), Cu (95.83%),Mn (66.44%), Cr (60.98%) and Fe (47.47%) %). However, septic tank had poor performance on removing turbidity (9.37%), COD (21%), TDS (27.45%), NO₃^- (-39.00%), SO₄^-2 (-3.24%), TKN (-5.04), TC (14.58%) and FC (20.23). Evidently, the septic tank treatment plant of study area was not effective on removing contaminants from the hospital, due to the absence of maintenance, lack of desluding, lack of preliminary/primary treatment and absence of secondary/ tertiary wastewater treatment system, lack of sound waste management system i,e sorting and disposal of hospital waste, and lack of proper operation and maintenance program. Therefore, there should be optimal treatment technology for hospital wastewater treatment and a continuous monitoring and evaluation of the effluent quality of the septic tank before discharging in to the environment is of paramount importance.

Keywords: Physicochemical parameters, Heavy metal, Bacteriological parameters, Septic Tank, Treatment efficiency