Five tons of BOD5 and high concentrations of nutrients and calcium were found in the wastewater of a dairy in Bavaria – at a level of 2,100 cubic metres per day. Since the batches in production change constantly, the degree of contamination and the pH value of the wastewater also varied greatly. This resulted in high wastewater fees. In order to significantly reduce these costs, the management of the dairy factory in 2004 decided to expand the wastewater treatment plant which had been in operation since 1993. This had also been supplied by H+E. The objective was to discharge the treated wastewater into a nearby river. The limit values of the wastewater regulations, however, required a significant reduction in the pollution load.
For this customer, H+E developed a plant extension based on the excellent operating experience with the existing plant. Wastewater streams with a high solids load are pre-treated by straining and flotation, and then collected, mixed, equalised, and neutralised in the buffer tank. The activated sludge process is divided into anaerobic, anoxic, and aerobic areas. This ensures that organic pollution, nitrogen, and phosphorus are eliminated to the greatest possible extent.
The high calcium concentrations in dairy effluents often lead to precipitation which can seriously damage the aeration system. For this reason, our experts chose the robust AEROFIT®.D aeration system developed by H+E for the expansion of this wastewater treatment plant. The activated sludge is treated in an aerobic digester for stabilisation. The nutrient-rich sludge, which contains only harmless substances, can then be used in agriculture.
Facts & figures:
- Discharge values far below the legal limits
- The local wastewater regulation requirements are consistently complied with
- Pollutant-free sludge
- Sludge usable on agricultural land