An inquiry into the polymer influence on flakes stability in the chemical conditioning of sewage sludge

الملخص EN

The process of sewage disposal, including the sludge of aerobic biological wastewater plants, is a growing ecological and economic problem which is widely debated nowadays.

Some related controversial concerns are the followings: First, the cost of sludge treatment and recycling is estimated at 30-60 % of the total annual plant budget cost.

Second, recently there are relatively few methods available for recycling.

Third, that heat treatment, resulted from combusting sewage, would be the most successful and expensive way in the future.

All these problems necessitate finding practical procedures for achieving a cost-effective streamlined drainage of sewage sludge.

This streamlined drainage requires a mechanical and economical pretreatment of sludge which includes both dewatering and conditioning of the sludge disposal.

Mostly, this pre-treatment (conditioning) of sludge can be done by using chemical means to facilitate adding doses of Flocculants (Polymers).

This study compares the polymer Eurofloc which is used by Seesen; a wastewater treatment plant in Germany, with other 14 different organic Flocculants.

It investigates the possibility of using alternative polymers to optimize the dewatering of sewage sludge.

In the process of theoretical investigation as well as the practical implementation, some precautions should be taken into consideration, such as the complete covering of all granule particles in water when preparing highly diluted solutions, or the necessary injection of the liquid polymer to keep it slow and therefore avoid unwanted lumps and the consequent melting.

In this study, an alternative polymer (Zetag 7689), which is comparable in performance to the Eurofloc used by Seesen, will be introduced.

The study will also include an explanation of (1) the alternative polymer characteristic of flakes stability in the continuing changed turbidity of the supernatant water, and the (2) comparative results of the reproducing and practical transferring of this alternative polymer for a better flake stability using turbidity measurements; a conclusion which was confirmed through actual technical use and implementation at Seesen.