Effluent treatment

Case studies

1. An effluent treatment plant was required for an overseas company discharging into a large inland lake. A survey and sampling programme was carried out to determine flow variations and effluent quality. Discussions were held with the local environment agency to establish discharge quality and use was made of local wetlands for effluent polishing. A scheme was implemented to reduce effluent in key areas and in particular remove some of the major polluting loads from the effluent stream. A specification and budget costing was drawn up to enable capital approval to be sought. Finalised P and I’s and layouts were drawn up to allow the project to be bid and implemented.

2. An effluent treatment plant was required for a Caribbean brewery discharging into the sea. The effluent was segregated into streams and it was decided to implement the treatment in stages and target the most polluting streams first with anaerobic technology. Subsequently the other stream would be added and the final effluent would be aerobically treated. A sampling regime was implemented and data drawn up for each stream with average and peak loadings. Capital budget costings were produced and several international contractors approached for proposals. The project is currently in the implementation stage.

3. A small U.K soft drinks producer experienced problems with pH control and had difficulty in meeting discharge consents. A major incident brought matters to a head and pressure from the Environment Agency forced the company to act. A survey of the existing plant and arrangements was carried out. Recommendations were made regarding containment design and recommendations for modifications were made to the pH control system and the type of acid being used.

4. An effluent plant at a UK paper mill was using unusually high amounts of polyelectrolyte . An investigation was carried out and it was discovered that although the dosing levels of polyelectrolyte were correct , a considerable amount of effluent recycling was being carried out such that the polyelectrolyte dose was two to three times the required amount. The process design was altered so that it was not required to recycle so much effluent and the treatment flowrate was altered instead.

5. A small UK company was faced with an increase in effluent charges from £10000 to £100,000 p.a because of increased charges from the water company. Although the company only produced a small quantity of effluent, this effluent had a very high COD. A proposal was made for anaerobic treatment of this effluent to reduce the load and charges resulting in a 2 year payback on capital investment.