Parasitological Profile of Raw Wastewater and the Efficacy of Biosand Filter in Reduction of Parasite Ova and Cysts

Abstract

The disposal of wastewater in water bodies has a negative impact in the environment and the health of people who use such water bodies for either irrigation or drinking purposes. In this study, we evaluated the parasitological profile of wastewater from the Ahmadu Bello University Teaching Hospital sewage treatment plant, Zaria, Nigeria using the magnesium sulphate floatation method. The parasite removal efficiency of biosand filter was also tested in comparison with the sewage treatment plant. A total of 960 L of wastewater was examined and a significant level of parasite eggs, cysts and oocysts were detected. In all, 1,648 parasites eggs, cysts and oocysts per litre were counted. Ova of Ascaris spp showed the highest count/litre of 307 (18.63%) followed by ova of Taenia spp (n=287; 17.42%). The least count per litre was exhibited by cysts of Giardia spp (n=58; 3.52%). The analysis revealed that 52.61% of the parasite eggs, cysts and oocysts was removed by the sewage treatment plant while egg removal efficiency of the biosand filter was 97.45%. Further comparison of mean parasite eggs/litre in the effluents of biosand filter and the sewage treatment plant using Wilcoxon's Signed Ranks Test indicated a significant difference (p < 0.05) with biosand filter having lower counts per litre. The results obtained therefore demonstrate that the raw wastewater was laden with parasite eggs, cysts and oocysts and hence pose public health threat to the users of the effluent downstream. The biosand filter was more efficient than the sewage treatment plant; its effluent contains insufficient level of the ova, cysts and oocysts of parasites well below the less than one (<1) helminth ova/protozoa cysts as recommended by WHO. © JASEM The practice of discharging wastewater into water bodies causes considerable damage to the ecosystem, waterfront inhabitants, swimmers, and fishermen (Hamdani and Assobhei, 2001; Paraskevas et al., 2002). Depending on its origin, wastewater can transport many pathogens depending upon the incidence of disease in the indigenous human and animal population that discharge to the sewer (Leclerc et al., 2002). Therefore, hospital wastewater is heavily laden with pathogens and toxic chemicals and hence requires adequate treatment to remove or appreciably reduce the available pathogens to a level that agrees with permissive ranges stipulated by regulatory authorities. The problem of contamination caused by the discharge of wastewater into water bodies is directly evident in intoxications, skin problems and intestinal parasitiasis (Rodriguez et al., 2004; Srikanth and Naik, 2004). This problem is compounded when these discharges are deposited in the vicinity of low-income neighbourhoods where basic hygiene practices are totally absent (Nyarango et al., 2008). Globally, millions of people suffer from parasitic infections such as Ascariasis (1.2 billion), Trichuriasis (795 million), hookworm infections (740 million) (de Silva et al., 2003), Amoebic dysentery (50 million) (Samuel et al., 2001) and Giardiasis (2.8 million) (Ali and Hill, 2003). In humans, these parasites are significantly associated with diarrhoea (Utzinger et al., 1999). Faecal oral route is important in the transmission of parasitic infections to humans via poor personal hygiene (Okyay et al., 2004), environmental conditions like contamination of soil and water sources with human faeces (Muttalib et al.,1983) and poor wastewater disposal such as use of night soil for fertiliser (Mustafa et al., 2001).