Factors Affecting Floc and Bulking in the Activated Sludge Process for Treatment of Textile Waste Waters

摘要

A textile and municipal wastes activated-sludge facility was studied microbiologically during normal sludge settling/bulking periods, and factors influencing the degree of microbial flocculation and effluent quality were examined. Total viable numbers of bacteria were determined, and isolates were taxonomically characterized. A filamentous bacterium (resembling Eikelboom's Type 0961, known to predominate some activated-sludge reactors with low food/microorganism ratios) was the most prevalent in bulking sludge. Prevalent genera indicated relative stability in the community population structure at this facility. Predominant bacteria were species of Acinetobacter, Alcaligenes, Pseudomones, and Flavobacterium. All bacteria isolates flocculated well in synthetic media and/or sterilized wastewaters. Unusually high COD/BOD ratios suggested an effluent of chemically low quality, and the dominance of small flagellates (Bodo sp. and Notoselenus sp.) implicated a resultant low quality effluent. Temperatures of 20-25 degrees and pH 8.5 support optimal settleability and lowest sludge volume index values. High sodium ion levels from the textile mill dramatically affected settleability, which improves with increasing divalent cation levels.