Research On New Process For Treatment Of Swine Wastewater

The wastes of livestock and poultry, especially the wastewater of swine have become the main pollution source in many districts of China. However, the intensive breeding industry will go on development and will inevitably produce more pollution in the next twenty years. Although swine wastewater can be treated by landspreading or ecological mode, the treatment needs vast land. So it will be confined by the available land in our country. Engineering treatment has to be chosen in the land-limited swine farms. In the engineering treatment, the investment and running cost are very high if raw swine wastewater is treated directly with an aerobic process. It is difficult either to treat the digested effluent when the combined anaerobic-aerobic process is used. In order to overcome the difficulty, we have investigated the suitable source of electronic donor and the methods for alkalinity balance in the post-treatment of digested effluent. The main achievements are as follows:(1) The feasibility of swine wastewater treatment with combined anaerobic (IC)-aerobic (SBR) process has been tested. The results showed that the organic loading rate was 6-7 kg COD/(m³.d), the COD removal percentage was about 80%, and the volumetric biogas production rate was 3 m³/(m³.d) in treatment of swine wastewater with Internal Circulation (IC) reactor. However, ammonia nitrogen could not removed, and the concentration of ammonia nitrogen (NH3-N) in digested effluent was even a little higher than that in influent. When Sequencing batch reactor (SBR) was used directly to treat digested effluent, the treatment efficiency was very poor. The COD removal percentage was approximately 10% with effluent COD about 1000mg/L. The NH₃-N removal percentage was about 70% with effluent NH3-N more than 200mg/L. The effluent of SBR process was far from "Discharge standard of pollutants for livestock and poultry breeding (GB 18596-2001)". The pH value lower than 6.0 in the mixed liquid at the end of aeration can explain the poor treatment efficiency of SBR. Regulating pH value by means of adding alkali could obviously...