Some effects of sodium pentachlorophenol on activated sludge and minnows.

The primary purpose of this investigation was to determine the effect of sodium pentachlorophenol on activated sludge. An additional objective was to determine the toxicity of sodium pentachlorophenol to minnows. All activated sludge units were grown on a glucose and mineral nutrient waste. In addition, a unit acclimated to 100 and 250 mg/1 of sodium pentachlorophenol was also studied. The effect of a shock loading of sodium pentachlorophenol was found to depend on the concentration of the loading and also on the group of micro-organisms which were predominating. One activated sludge system was seriously impared at a shock loading of 10 mg/l; yet, another system was not seriously impared until the concentration of the shock loading was 30 mg/1. The acclimated unit significantly reduced the organic content of the glucose waste within six hours; however, the concentration of biological solids was much lower and the oxygen utilization rate was much higher in this system than in the systems receiving the glucose waste only. It was also found that the acclimated unit remained a completely dispersed system. In all cases sodium pentachlorophenol was found to increase the production of cellular protein and to inhibit the production of carbohydrate. Sodium pentachlorophenol was found to be resistant to biological attack. The studies with minnows established that the 48-hour median tolerance limit is 1.0 mg/l of sodium pentachlorophenol. It was also established that concentrations as low as 0. 4 mg/l are toxic to fish --Abstract, pages ii-iii