不同缺氧段硝酸盐氮浓度条件下连续流单污泥污水处理系统PHA、TP代谢

根据试验结果和物料平衡分析,揭示了连续流单污泥污水处理系统在不同主要缺氧段硝酸盐氮质量浓度c(NO3)]条件下运行时的PHA、TP代谢规律,从反应机制方面评价以c(NO3)作为连续流单污泥污水处理系统运行控制参数的有效性.采用PLC自动控制系统,以硝化液内循环流量作为被控变量,基于反馈控制结构,在c(NO3)设定值分别为0.5、1.0、1.5、2.0、2.5、3.0、3.5以及4.0 mg·L-1的条件下进行试验研究,进水水质及其他运行设计参数保持不变.结果表明,当c(NO3)设定值为2.5mg·L-1时,厌氧段和预缺氧段PHA合成并贮存量、主要缺氧段PHA降解量、厌氧段和预缺氧段磷释放量、系统总吸磷量以及主要缺氧段磷吸收量等均达到最大值,分别为35.32、1.71、20.44、6.16、0.32、8.04、3.67 g·d-1.这从PHA和TP代谢机制角度进一步证实了c(NO3)可作为连续流单污泥污水处理系统的运行控制参数,其最佳设定值为2.5 mg·L-1.

Concentration of Nitrate in Main Anoxic Stage and PHA, TP Metabolism for Nitrogen and Phosphorus Removal in Single Sludge System with Continuous Flow

Based on test results and mass balance, PHA, TP metabolic regularity was revealed under different nitrate nitrogen concentrations in main anoxic stage c(NO₃)] for nitrogen and phosphorus removal in single sludge system with continuous flow, then the effectiveness of using c(NO₃) as control parameter was proved from the perspective of the reaction mechanism. During experiment period, the influent COD, total nitrogen (TN), and total phosphorus (TP) concentrations were stabilized at (285.78±18.19), (58.13±3.79), and(7.14±0.51) mg·L^-1, respectively. The experiment was carried out under the condition that the c(NO₃) values were 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 mg·L^-1 based on the feedback control structure using PLC automatic control system to control the nitrifying liquid flow with the water quality. The sludge load of COD was (0.253±0.071)kg·(kg·d)^-1, the sludge load of TP in anaerobic stage was (0.006±0.001) kg·(kg·d)^-1, the sludge load of TN in aerobic stage was (0.049±0.006) kg·(kg·d)^-1, the hydraulic retention time (HRT) in bioreactor was 9h, the sludge recycle flow was 0.5, and the mixed liquor recycle was 1.0. The results showed that effect of c(NO₃) value on PHA synthesis and storage rate in the ANS was conspicuous, and the percentage of PHA storage occupied 74% of COD removal when c(NO₃) value was 2.5 mg·L^-1.The impact of c(NO₃) value on PHA degraded in the main anoxic stage was great, and the percentage of PHA degradation in the main anoxic stage occupied 55% of total PHA degradation when c(NO₃) value was 2.5 mg·L^-1. The phosphorus released in anaerobic stage changed along with increasing c(NO₃), and the amount of phosphorus released obtained the maximum value 6.16 g·d^-1 when c(NO₃) value was 2.5 mg·L^-1. In addition, under c(NO₃) value of 2.5 mg·L^-1, the amount of total phosphorus uptake and anoxic phosphorus uptake obtained the maximum values of 8.04 g·d^-1 and 3.67 g·d^-1, respectively. Then it was confirmed thatc(NO₃) could serve as a run controlling parameter with the best value of 2.5 mg·L^-1 from the perspective of PHA and TP metabolic mechanism.