pH值对化学-生物混合污泥厌氧发酵释磷的影响

Effect of pH on phosphorus release from chemical-biological mixed sludge during anaerobic fermentation

以污水处理厂化学除磷工艺产生的常见化学磷（AlPO4和FePO4）沉淀为研究对象,考察了两种化学磷分别与剩余活性污泥（即生物污泥）混合厌氧发酵过程中化学磷和生物磷的释放情况.结果表明：在纯水中,AlPO4在强酸强碱条件下均能释出部分磷,FePO4只在强碱条件下才能溶解释磷.在（35±1）℃,不同pH值下将含AlPO4的混合污泥厌氧发酵时,强酸性厌氧发酵能释出较多的化学磷,但微生物活性被抑制,不利于发酵产酸；碱性发酵（pH=10-11）能释出28%-55%的化学磷,43%-49%的生物磷,总释磷量比中性条件下高17.5%-62.7%,同时利于发酵产酸,维持pH 10和11时产酸量分别比中性条件高233%和117%；对于含FePO4的混合污泥厌氧发酵,中性条件下即能释放FePO4中40%的磷和生物污泥中50%的磷,释磷量高于pH=11的碱性厌氧发酵释磷量.

Two chemical phosphates （AlPO 4 and FePO4） were usually generated during chemical phosphorus removal processes in wastewater treatment plant. To investigate the release of chemical phosphates and biological phosphorus when each chemical phosphate was mixed with surplus active sludge （biological sludge） respectively for anaerobic fermentation, the two chemical phosphates were used. The results showed that in pure water, phosphorus could be released from AlPO4under either strong acid or strong alkaline conditions, and be released from FePO4only under strong alkaline conditions. For anaerobic fermentation of mixed sludge containing AlPO4at 35-1℃, more chemical phosphate could be dissolved under strong acid but microbial activity was inhibited, which was unfavorable to volatile fatty acid （VFA） production. Under alkaline conditions （pH=10-11）, 28%-55% of the chemical phosphate and 43%-49% of the biological phosphorus were released and the total released phosphorus amount was 17.5%-62.7%higher than those under neutral condition. Alkaline conditions were also beneficial to VFA production;at pH=10 and pH=11, VFA production was 233%and 117%higher than those under neutral conditions, respectively. For anaerobic fermentation of the mixed sludge containing FePO4, 40%of chemical phosphate and 50%of the biological phosphorus in sludge could be released under neutral condition, which were higher than those under alkaline condition （pH=11）.