Abstract
Physicochemical studies on wastewater quality and microscopic analyses of activated sludge are necessary to properly evaluate the condition of activated sludge. The aim of this study was to evaluate the application of the sludge biotic index to determine when a change in treatment quality is short-lived, caused by, e.g., a change in influent quality or quantity, and when it indicates adverse changes in the biocenosis of activated sludge, which would very likely result in the lower efficiency of wastewater treatment in the near future. The objects of the study were two identical parallel running small wastewater treatment plants. The following indicators of contamination were analyzed: the chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and total suspended solids (TSS). The authors additionally carried out a microscopic analysis. The study confirmed a correlation between the sludge biotic index and the removal efficiency of COD and BOD5; however, no correlation was found between the sludge biotic index and the removal efficiency of total suspended solids. The presence of metazoan microorganisms coincided in time with a good effluent treatment efficiency. When their quantity declined, a decrease in the efficiency of wastewater treatment was also observed.
Highlights
IntroductionThe first research on activated sludge was carried out in England and the United States at the end of the 19th century
COD and BOD5 were an analysis of the following of contaminants was carried out: the chemical oxygen demand determined through spectrophotometry, and total suspended solids (TSS) total by a suspended direct weight measurement
The presence of metazoan microorganisms coincided in time with a good effluent treatment efficiency
Summary
The first research on activated sludge was carried out in England and the United States at the end of the 19th century. In the 1880s, the primary scientific objective was to remove odours from wastewater. Significant experiments were conducted between 1912 and 1913 at Lawrence Experimental. Station of Massachusetts State Board of Health (the USA); they did not produce satisfactory results. Members of the River Committee of the Manchester
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