Analysis of capability of different waste water treatment systems in purifying sewage in large-scaled pig farms

The integrated planting and breeding model is widely accepted in south China. 12 large-scaled pig farms were selected and were divided into four groups according to their sewage treatment systems，the first one was defined as pannage-methane tank-planting pattern；the second one was pannage-methane tank-fishing pattern；the third one was pannage-methane tank-planting-fishing pattern and the fourth one was pannage-methane tank-fishing combined with concentrated methane supply pattern. The first sewage facility was anaerobic fermentation system and the second facility was fishpond and some other ecological engineering. The pollutant concentration in different treatment models showed that anaerobic fermentation system showed good effect on reducing fecal coliforms and in some extent，also on reducing total soluble suspends. However，the naerobic fermentation system displayed a limited purification of nitrogen and phosphorus. Fishpond and some other ecological engineering made a good performance in reducing several pollutants in sewage. A comprehensive evaluation on the capability of waste water treatment system in purifying sewage was carried out，the results showed that the third pattern was the best，followed by the fourth pattern，then the second pattern，the last one was the first pattern.