Labscale Anoxic Stabilization Ponds Operated under High Organic Loads: Long Term Effect of Enrichment with Activated Sludge

Abstract

The addition of acclimatized activated sludge has been suggested as an effective enrichment procedure to increase the biological activity of waste stabilization ponds. This enrichment results in higher degradation rates compared to non enriched stabilization ponds. However, the comparison between enriched and non enriched ponds has been observed during short term experiments and it is unknown if this enrichment has long-term effect. This paper compares enriched and non enriched experimental ponds over two years of continuous operation. The enriched pond showed a degradation activity constantly twice higher. The biological indicators such as the heterotrophic and facultative plate count numbers, the chlorophyll "a" concentration and the oxygen consumption rate were also constantly higher in the enriched pond. These results suggest that an initial enrichment has a long term enhancement effect on stabilization ponds treating complex wastewaters.