Chemical contaminants reduction of wastewater used for peri-urban agriculture in northern Ghana

Wastewater irrigation can pose a variety of potential risks, excessive and often imbalanced addition of nutrients to the soil thus affecting crop production. Objective of the study was to reduce the level of chemical contaminants of wastewater used for peri-urban vegetable crop production by poor farmers in the Tamale Metropolis of Northern Ghana. Studied parameters included ammonia (NH3), nitrate (NO3-), nitrite (NO2-) and phosphorus (P) and pH. Experimental setup was horizontal trickle sand filters combined with farm stabilization ponds with the working principle based on filtration theory. Results revealed the level of reduction of ammonia to be statistically significant in the wet season whiles both NO3-, and NO2-, recorded significant level of reduction in the dry season. Seasonal changes coupled with climatic variations were identified as factors which influenced the general response of chemical parameters to treatment. Ammonia levels ranged between 14.6 to 27.0 mg/l with 51.2% reduction level which was far above EPA Ghana recommendation. Levels of NO3- were lower than EPA Ghana standards, ranging from 0.293 to 3.80 mg/l with 49.4% reduction level. NO2- level ranged from 0.073 to 2.07 mg/l with 31% reduction level whiles phosphorus levels which ranged from 1.63 to 1.87 mg/l recorded insignificant reduction level.