Anaerobic Treatment Of Percolate From Faecal Sludge Drying Beds

Abstract

Composite percolate samples, from sludge drying beds of a pilot co-composting plant in Kumasi, Ghana, were characterised and subjected to laboratory scale anaerobic treatment. Two categories of percolate samples were investigated; samples seeded with
anaerobic sludge and samples without seeding. The average percentage removals for the unseeded percolate after 6 days of treatment were 63.6%, 51.2%, 57.1%, 27.5% and 26.1% for Suspended solids (SS), Chemical oxygen demand (COD), Biochemical oxygen demand (BOD), Phosphate-Phosphorus (PO -P) and Faecal coliform respectively. For the seeded percolate, the removals were 68.4%, 55.9%, 57.5%, 15.5% and 27.6% respectively for SS, COD, BOD, PO -P and Faecal coliform. Thus, for anaerobic treatment of the percolate no seeding is required. The anaerobic treatment could not produce the desired quality for
reuse or discharge into water bodies. The composite percolate exhibited average quality of 413 mg/l SS, 3,280 mg/l COD, 647 mg/l BOD, 409 mg/l NH -N, 266 mg/l PO -P, 1.12 x 10 Faecal coliforms/100ml and 0 Helminth eggs/litre. These values, except for Helminth eggs, when compared with the recommended discharge standards show that the percolate is poor in quality and thus requires treatment prior to reuse or discharge into the environment. It was therefore recommended that additional treatment is necessary to further lower the pollution load of anaerobic treated percolate and to reduce the public health risks. However, it may be possible to use the percolate to moisten the compost windrows during the early period of composting.

Keywords: Anaerobic, drying bed, faecal sludge, percolate, treatment

Journal of the Ghana Institution of Engineers Vol. 5 (1&2) 2007: pp. 25-30