Optimization of Wastewater Phosphorus Removal in Winter Temperatures Using an Anaerobic–Critical Aerobic Strategy in a Pilot-Scale Sequencing Batch Reactor

Abstract

Biological phosphorus removal using an anaerobic-aerobic sequencing batch reactor (SBR) in a low temperature can be difficult to remove, and aeration always accounts for nearly half of the total electricity costs at many wastewater treatment plants. In this study, a pilot-scale anaerobic-critical aerobic SBR (A-CA SBR) was developed for synthetic domestic wastewater. More importantly, the phase, whose concentration of diffused oxygen was controlled at 1.0-1.5 mg/L, was defined as a critical aerobic phase, which reduced expenses during the operation. To be specific, half of the ammonia was removed within 10 days and no NO 3 − -N was accumulated during the process.From the SEM and metagenome analysis, Rhodocyclus, Zooglea, Dechloromonas, and Simplicispira had the ability to remove phosphorus and NO 3 − -N simultaneously, which proved the existence of a potential double-layer sludge structure under an A-CA operational condition. All of the results disclose that the pilot-scale A-CA SBR is a reliable manipulation strategy for phosphorus removal under low temperatures, which can hopefully apply to practical wastewater remediation.Among all of the influenced parameters, temperature is a vital factor in the phosphorus uptake process. Li et al. reported that 20 • C or possibly lower was suitable for P removal of microorganisms [2], and Liu and Li showed that temperatures below the optimum range had more significant effects on growth rate than those above the optimum range, because the activities of the microorganisms sharply decreased with the decreasing temperature. So, it was more difficult to realize phosphorus removal at a low temperature [10]. Additionally, Liu et al. [11] investigated the influence of temperature on denitrifying phosphorus removal (DPR), and found that more than 80% of phosphorus removal from DPR was obtained in the range of 20-30 • C, and the removal efficiencies went down when the temperature was below 10 • C. However, in the north of China, temperature changes drastically when the season varies. Especially in winter, wastewater is at low temperatures (11-13 • C) for a long period, which results in a negative impact on the performance of phosphorus removal [12]. Therefore, it is crucial to find a solution to treat wastewater in low temperatures properly.It has been noted that most studies have been focused on lab-scale SBR [3,7,13,14], and pilot-scale SBR are reported on less. In this study, the phase whose concentration of diffused oxygen was controlled at 1.0-1.5 mg/L was defined as a critical aerobic phase. A pilot-scale anaerobic-critical aerobic (A-CA) SBR, which had a good adaption, high efficiency, and strong practicality [15], was designed to remove phosphorus in wastewater under cold temperatures. During the operation process, a sludge structure of the inner anoxic zone and outer-critical aerobic layer was found, and metagenome analysis proved the microorganism's variation. In addition, the optimization of the length of the critical aerobic phase was investigated in order further to obta...

Deployment and Optimisation of a Pilot-Scale IASBR System for Treatment of Dairy Processing Wastewater

“…Capacity to biologically remove this nutrient will significantly reduce operational costs as biological phosphorus removal is one of the most cost-effective methods of phosphorus removal [14]. To date there has been limited success on a consistent basis for biological P removal within the dairy industry, with many systems often suffering from inconsistent or inadequate performance, and it is reported that although there has been extensive research into biological P removal in SBRs at lab scale, research into biological P removal at pilot scale is not as well documented, thus highlighting the need to conduct research at pilot scales to demonstrate how stable P removal can be achieved on-site [14,38]. Novel methods of biological phosphorus removal which are more robust will allow operators to reduce chemical use and cost.…”