Reduction of Activated Sludge Production by Means of Electromagnetic Waves Treatment
Izazy M. H., University of Savoie, Le Bourget-du-Lac, France
The reduction of activated sludge production in wastewater treatment plants is an important issue. Urban wastewater sludge represents 1300 000 tons of dry matters formed annually in France: 60 % of sewage sludge is directly applied to agricultural soil, 15 % is incinerated, and 25 % is landfilled. The increase in sludge productions and restrictions of the new legislation on discharge represent a real problem for sludge management. It thus appears essential to develop integrated systems of wastewater treatment enabling to reduce sludge production.
The effects of electromagnetic field on activated sludge in a lab-scale pilot plant containing synthetic wastewater have been researched in this paper.
The wastewater has been exposed to extremely low-frequency electromagnetic fields in the range 2—50 Hz; two frequencies have been tested during our study. The strength of electromagnetic field applied in our study was very small and ranged from some mT to some uT.
Accordingly, the electromagnetic field influence on the production of activated sludge, the organic compound removal from domestic wastewater, and the sedimentation of sludge has been investigated. We have found that the efficacy of electromagnetic treatment is frequency dependent.
The electromagnetic electrode had been set directly in the aeration basin. Reduction of sludge production became evident during two tests. The first study showed very promising results (30 % reduction, knowing that the reduction of 5 % may already be financially very interesting). The second study continued over 3 months and brought new interesting results (reduction of over 12 %).
Also, we found that the effect of electromagnetic treatment on the sedimentation of sludge is an inhibitory or stimulatory effect depending on the frequency of electromagnetic field. In fact, the electromagnetic treatment is an innovative way of activated sludge reduction to make it inexpensive (low investment and low energy consumption) and environmentally friendly. It would improve the operation of sewage treatment plants and reduce the costs and energy consumption (transport but especially incineration). There is therefore a strong ecological interest in this treatment method.
Izazy Muhammad Hayssam, Ph. D. student, University of Savoie, 789 rue des combes — Chambery, 73000, Le Bourget-du-Lac, France. Tel. 621-602-502. E-mail
© Последние изменения внесены 15.10.09
© EcoInform