Determination of organic loading rate of activated sludge plants based on protozoan analysis

• Published in: Water research (Oxford) 1993, Vol.27 (5), p.891-895
• Main Authors: Salvadó, H., Gracia, M.P.
• Format: Article
• Language: English
• Subjects: activated sludge; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; ciliates; diversity; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Fundamental and applied biological sciences. Psychology; Invertebrates; organic loading rate; protozoa
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/0043-1354(93)90154-A

Variations in the structure of the protozoan community living in activated sludge were studied in relation with the organic loading rate. 84 samples were taken over a 14 month period. Sludge and wastewaters were subjected to microscopic and physico-chemical analyses. The organic loading rate corresponding to each microscopic count was determined as the average of the values calculated for the 2 days previous to the count. Ciliate species abundance and specific diversity of ciliates were strongly related to the organic loading rate. Data were compared to three other facilities. Ciliate diversity decreased as the organic loading rate increased. This relationship could be modified if solids in suspension surpassed 4000 MLVSS mg/l or if volumetric loading rates were higher than 800 g BOD 5/m 3 day. An easy, fast diagnostic test to estimate the organic loading rate in less than 5 days and to obtain information on plant performance is proposed.