The Pro-Active System (PAS) for sewage treatment in rural areas
1997
Kuai, L. | Kerstens, W. | Verstraete, W. (Gent Univ. (Belgium). Faculty of Agricultural and Applied Biological Sciences)
The pro-active system (PAS) is a sequence of "coagulation sedimentation - trickling filter" which was applied to treat a household wastewater in a lab scale treatment unit. By adding 5 mg per litre of poly-electrolyte, about 90 per cent of CODt was removed in the coagulation process. Charcoal was used as carrier in the trickling filter. The final effluent CODt from the trickling filter amounted to 20-70 mg per liter. Nitrification occurred in the trickling filter from week 3 onwards. The total removal of NH4-N and Kj-N amounted to 79 and 91 per cent, respectively. The remained Kj-N in the final effluent was about 14 mg per liter. Chemical-physical removal of total phosphate (Pt) was the dominant process. About 62 per cent of Pt was removed. The residual Pt in the final effluent averaged 10 mg per litre. The integrated treatment system achieved a fair degree of hygienisation. It reduced the total coliform (TC), fecal coliform (FC) and fecal streptococci (FS) by 2-4 log units. The primary sludge discharged from the septic tank was mixed with a type of super-absorbent for sludge dewatering. The water saturated super-absorbent was dried by natural evaporation. The dried sorbent could be reused several times in a new cycle. The technical skills and the costs related to the system appear appropriate for a family or a small community. In Flanders (Belgium), the operational cost saved by this system appears to be of the order of 60 per cent of the cost of a conventional activated sludge system.
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