Studying the technology of wastewater sludge chemical dewatering with the help of experimental-statistical models

Summary

The results of experimental studies of the specific resistance of raw wastewater sludge changing under the effect of six types of coagulants and a polyacrylamide flocculant at doses ranging from 0 to 5.25 g/kg dry matter are presented. The effect of each chemical on the raw sludge dewatering rate is determined. Mathematical models are obtained for the dependence of changes in sludge specific resistance on the coagulant and flocculant amount added. The mathematical models are presented both as implicit and explicit equations, and as explicit isolines. It is proven that more expedient is using polyoxyaluminum sulfate and aluminum sulfate coagulants at a dose of up to 5.25 g/kg dry matter and a polyacrylamide flocculant at a dose of 5.25 g/kg dry matter which provide for maximum reducing the raw sludge specific resistance.

Key words

primary settler , optimal dose of chemicals , sludge specific resistance , сырой осадок сточных вод , mathematical and graphical models of sludge water yielding capacity

Experimental and statistical models of the water yielding capacity of domestic wastewater sludge after chemical treatment

Summary

The results of studying the change in the specific resistance of wastewater sludge after treatment with a coagulant and flocculant in doses from 0 to 300 mg/dm³ are presented. The degree of the chemical effect on the sludge dewatering efficiency is established. Mathematical models of the changes in the sludge specific resistance depending on the type and quantity, as well as on the doses of coagulant and flocculant added into the sludge are obtained. The mathematical models are presented both implicitly and explicitly (calculation formulas and isolines). It was proved that to provide for the maximum reduction of the specific resistance: of raw sludge using a coagulant dose of up to 100 mg/dm³ and a PAA flocculant dose of 300 mg/dm³ was more expedient; of excess activated sludge – using a coagulant dose of 150 mg/dm³ and a PAA flocculant dose of 50 mg/dm³; of thickened activated sludge – using a coagulant dose of 100 mg/dm³ and a PAA flocculant dose of 300 mg/dm³; and of mixture of raw sludge and thickened activated sludge – using a PAA flocculant dose of 200 mg/dm³. Measuring the sludge density showed that the lower is the sludge specific resistance, the higher its density is.

Key words

sludge , optimal dose of chemicals , mathematical and graphic models of sludge water yielding capacity , sludge specific resistance , density