Development of flexible fibre biofilm reactor for treatment of food processing wastewater

Biological treatment methods are usually effective and commonly used in the treatment of organic wastewater. However, there are a number of problems for conventional biological treatment methods in treating wastewater from industries such as food processing. For example, microorganisms in the aeration tank in an activated sludge process cannot survive a continuous series of shock loads and the process could become operationally unstable. The associated problem of sludge bulking often occurs when the organic loading to the treatment process is high. In this paper, a new flexible fibre biofilm reactor was developed for the treatment of wastewater from fruit and vegetable processing plants. Experiments were carried out to evaluate the performance of the treatment process. Acclimatisation characteristics of the treatment process were also evaluated. The removal efficiencies for COD and BOD5 for different influent organic strengths were evaluated. Results indicated that over 90% COD removal and 95% BOD5 removal could be achieved. The performance parameters were also compared with a conventional activated sludge process under similar conditions, operated in parallel. It was found that the biofilm reactor exhibited a number of advantages over the conventional reactor. These include (a) high organic loading rate, (b) long sludge retention times and low sludge discharge rate in the settling tank (about 10%), (c) elimination of the sludge recycle stream, and (d) no sludge bulking problem at high organic loading rates. Therefore, the flexible fibre biofilm reactor can provide a more efficient and cost effective treatment for wastewater from food processing industries.