TREATMENT EFFICIENCY OF WASTE STABILISATION PONDS FOR FAECAL SLUDGE AND POTENTIAL REUSE IN AGRICULTURE

Abstract

The upsurge in urban population has led to an increased generation of faecal sludge (FS) which contains large amounts of plant nutrients, as well as micro-organisms that may cause health hazards and contamination of the food chain, when faeces are used untreated to enhance crop productivity. Treatment ponds are designed to reduce organic, nutrient and pathogen load in faecal effluent. The current study was designed to evaluate the treatment efficiency of faecal sludge stabilisation ponds made of two anaerobic, primary and secondary facultative and a single maturation pond at the Tamale Metropolis landfill site. Spectrophotometer, microscope, incubator among others, aided in laboratory analyses of FS quality parameters. Annual FS discharge in the range of 6661.2 m3/yr to 17290 m3/yr was realised for year 2008 and 2013 respectively, with an average volume of 12321 m3/yr, increasing at a rate of 22.42 %/yr. Generally, the anaerobic pond recorded higher level of all the faecal sludge quality parameters except for pH, and temperature, whereas the maturation pond recorded the lowest, aside temperature, pH, N02' and N03-. Ascaris lumbricoides, Strongyloides stercoralis and Necator americanus were mostly the dominant helminth eggs parasites in all the ponds. Diversity profile analysis revealed that helminth eggs are highly diverse in the primary facultative pond and least diverse in the secondary facultative pond. The overall performance of the faecal sludge stabilisation pond is, on average, rated at 65.05 % removal efficiency. Performance efficiencies of 54.34 %, 64.49 % and 76.33 % were recorded for primary facultative pond, secondary facultative pond and the maturation pond respectively. Treatment effect on the concentration of FS quality parameters was statistically significant, except for temperature, COD, N03- and N02- Apart from temperature and N03-, levels of all quality parameters were relatively higher than the Ghana EPA recommended limit, thus faecal sludge quality may be unsafe for agricultural purposes. General maintenance as well as further research work on the performance of the treatment ponds is recommended.