内源电子受体产生及其在抑制富磷剩余污泥释磷行为中的应用

根据生物脱氮除磷系统产生的富磷剩余污泥含有硝化细菌和生产废水含有高浓度氨氮的特点,将生产废水中的氨氮转化为硝酸盐(内源电子受体),并将获得的内源电子受体利用在富磷剩余污泥浓缩过程,同步实现内源电子受体反硝化及其抑制富磷剩余污泥释磷行为。结果表明,将富磷剩余污泥(excess activated sludge,EAS。EAS1是在好氧方式下添加,EAS2是在缺氧方式下添加)与生产废水(reject water)按4种比例(Ⅰ、生产废水∶EAS1∶EAS2=15%∶85%∶0%;Ⅱ、生产废水∶EAS1∶EAS2=15%∶80%∶5%;Ⅲ、生产废水∶EAS1∶EAS2=15%∶75%∶10%;Ⅳ、生产废水∶EAS1∶EAS2=15%∶65%∶20%)混合曝气用于产生内源电子受体时,最佳硝化时间均为12 h,可将液相中的氨氮分别由初始的(113.16±0.85)mg/L、(117.18±4.39)mg/L、(129.48±4.85)mg/L及(142.53±0)mg/L降至(0.74±0.41)mg/L、(0.45±0.15)mg/L、(0.41±0.15)mg/L及(0.38±0.08)mg/L;同时,硝酸盐氮分别由初始的(7.48±7.91)mg/L、(12.87±5.81)mg/L、(12.87±5.81)mg/L及(13.55±6.18)mg/L升为(128.37±11.03)mg/L、(141.43±12.71)mg/L、(148.01±14.84)mg/L及(146.22±7.53)mg/L。内源电子受体可将重力浓缩过程中释磷量分别削减85%、63%、64%及83%,同时使得由生产废水回流引起的氨氮积累量分别减少89.25%、69.93%、74.31%及85.40%。在整个内源电子受体产生及其应用于抑制污泥释磷阶段,TN去除率分别为39.59%、44.54%、51.86%及57.33%。上述内源电子受体胁迫条件下的浓缩过程中,不仅可以有效降低由重力浓缩释磷引起的磷积累量,且可同步实现减少由生产废水回流引起的氨氮积累量。

In-stream electron acceptor generation and its application in inhibiting P-release behavior of P-rich excess activated sludge

According to the characteristics of inherent nitrifying bacteria of P-rich excess activated sludge (EAS,EAS₁ meaning excess activated sludge added under the aerobic condition;EAS₂ meaning excess activated sludge added under the anoxic condition) and high concentration of ammonia nitrogen in reject water, a novel in-stream electron acceptor, which generated from the reject water treatment process, was used to control P-release from the P-enriched EAS and was denitrified during gravity thickening process. The results indicated that the optimal nitrification time for in-stream electron acceptor (i.e. nitrate) generation was determined as 12 h when P-rich EAS and reject water mixed with four different ratios(I: reject water:EAS₁:EAS₂=15%:85%:0%; II: reject water:EAS₁:EAS₂=15%:80%:5%;III: reject water:EAS₁:EAS₂=15%:75%:10%; IV: reject water:EAS₁:EAS₂=15%:65%:20%) and aerated. This can lead to the ammonia nitrogen in the reject water decreased from (113.16±0.85)mg/L, (117.18±4.39)mg/L, (129.48±4.85)mg/L and (142.53±0)mg/L to (0.74±0.41)mg/L, (0.45±0.15)mg/L, (0.41±0.15)mg/L and (0.38±0.08)mg/L, respectively. The resultant nitrate increased from (7.48±7.91)mg/L, (12.87±5.81)mg/L, (12.87±5.81)mg/L and (13.55±6.18)mg/L to (128.37±11.03)mg/L, (141.43±12.71)mg/L, (148.01±14.84)mg/L and (146.22±7.53)mg/L, respectively. In-stream electron acceptor generated from the four operating conditions was further used as inhibitor to reduce the amount of P-release from EAS during the gravity thickening process effectively. 85%, 63%, 64% and 83% P-feedback and accumulation caused by the P-release from EAS were decreased, respectively. While, 89.25%, 69.93%, 74.31% and 85.40% of ammonia nitrogen feedback and accumulation through reject water were eliminated, respectively. During the stages of application of in-stream electron acceptor in inhibiting P-release behavior of excess activated sludge, the TN removal efficiencies were 39.59%, 44.54%, 51.86% and 57.33%, respectively. The application of in-stream electron acceptor can eliminate the P and N feedback in the biological nutrient removal process significantly.