Assessment of potential health risks of waste stabilization ponds effluents and sludge use for irrigating vegetables: a case of Lemara WSPs: Arusha municipality, Tanzania

For more than three decades, Waste Stabilization Ponds (WSP) effluent have been used by people of Lemara in Arusha Municipal to irrigate their farms in order to get better crop yields as source of their food and income. Despite of highly acceptance of wastewater reuse by the people in Lemara, there has been no effort to assess the health impact associated with wastewater reuse practices in this area. This study present results of assessing the current performance of WSP and the quality of wastewater used for irrigation to see if treated wastewater comply with WHO guidelines, assessment of sludge & soil. Grab samples were taken on a fortnightly and monthly basis in four points along the ponds system and examined in water quality laboratory for Faecal coliforms (FC), Helminth eggs, Temperature, pH, EC and BOD5. Results have indicated that WSP in Lemara reduces BOD5 by about 87.7% resulting in the average effluent of 79.3mg/l, which is higher than the recommended standards (30 mg/l). The presence of very high FC (440- 945 x 103 No/100ml) in the effluent of maturation pond is an indication of poor performance of ponds and as such Medium health risk category was identified during the assessment. helminth eggs were found in high level at the raw sewage, they significantly reduced along the treatment plant. Vegetables irrigated by WSP effluents also observed to have pathogen contamination. Sludge was observed to accumulate at the centre of anaerobic pond and heavy metals were seen at low concentration in the sludge and soil.