Seasonal Variation and Removal of Organic Pollutants in Wastewater Using Low-Cost Treatment Technologies in Tamale Metropolis, Ghana

摘要

The use of wastewater as alternative source of water for vegetable crop irrigation has become an eminent component of urban agriculture due to current global water crises in most developing countries, and admits the increasing effects of global climate change. The practise is however noted to be associated with significant health and environment risk due to excessive pollutant load. The study assessed the level of seasonal variation and removal of organic pollutants in wastewater using gravel filters combined with stabilisation ponds at Zagyuri in the Tamale Metropolis. The yard scale experiment consisted of cylindrical containers of different length filled with six different sizes of filter media and connected to stabilisation ponds where wastewater is allowed to pass through for filtration and stabilisation. The results indicated that for both seasons, the average concentration of BOD released into the stream at Zagyuri was 92.98 mg/l and 103.54 mg/l for the dry and wet season respectively whilst the COD was averaged 132.78 mg/l and 143.75 mg/l for the dry and wet seasons respectively. The results of the simple linear regression revealed a strong positive linear relationship between BOD and COD with coefficient of determination (R~2) of 0.873 which was statistically highly significantly at Pr value of ＜0.0001. The results for ANOVA for the treatment factor were statistically highly significant at Pr values of 0.0011 and ＜0.0001 respectively for BOD_5 and COD. The average concentration of BOD was higher than the Ghana EPA recommended levels while that of COD was lower and thus within safety range for discharge into the environment.