An efficient process for wastewater treatment to mitigate free nitrous acid generation and its inhibition on biological phosphorus removal

Abstract

Free nitrous acid (FNA), which is the protonated form of nitrite and inevitably produced during biological nitrogen removal, has been demonstrated to strongly inhibit the activity of polyphosphate accumulating organisms (PAOs). Herein we reported an efficient process for wastewater treatment, i.e., the oxic/anoxic/oxic/extended-idle process to mitigate the generation of FNA and its inhibition on PAOs. The results showed that this new process enriched more PAOs which thereby achieved higher phosphorus removal efficiency than the conventional four-step (i.e., anaerobic/oxic/anoxic/oxic) biological nutrient removal process (41 ± 7% versus 30 ± 5% in abundance of PAOs and 97 ± 0.73% versus 82 ± 1.2% in efficiency of phosphorus removal). It was found that this new process increased pH value but decreased nitrite accumulation, resulting in the decreased FNA generation. Further experiments showed that the new process could alleviate the inhibition of FNA on the metabolisms of PAOs even under the same FNA concentration.

Full-scale evaluation of aerobic/extended-idle regime inducing biological phosphorus removal and its integration with intermittent sand filter to treat domestic sewage discharged from highway rest area

“…Thus TN removal performance would be improved if we inserted anoxic phases into the aerobic phase, which has been verified by our recent parallel researches [3]. In addition, previous studies have verified that when receiving the same level of nitrate, the transformations of metabolic intermediates in the AEI regime are much lower influenced than those in the A/O regime [17], indicating that the AEI regime could tolerate a higher level of negative impact caused by nitrogen removal.…”

“…In addition, previous studies have verified that when receiving the same level of nitrate, the transformations of metabolic intermediates in the AEI regime are much lower influenced than those in the A/O regime [17], indicating that the AEI regime could tolerate a higher level of negative impact caused by nitrogen removal. Despite only highway rest area domestic sewage being tested in this study, our previous researches have demonstrated that excellent P removal can be achieved in the AEI regime using either synthetic or real common sewage [3,16,17,19,39]. Accordingly, the AEI regime might serve as a scientific basis for developing a new efficient solution to the "nitrogen-phosphorus challenge" faced by WWTPs.…”

“…During the past few decades, numerous studies have already been performed on this topic [1][2][3]. However, most of these investigations to date have focused on centralised wastewaters due to their massive quantities daily treated [4][5][6].…”

Free nitrous acid serving as a pretreatment method for alkaline fermentation to enhance short-chain fatty acid production from waste activated sludge

“…Meanwhile, as a byproduct of wastewater treatment, waste activated sludge (WAS) is generated in huge quantities daily (Ni and Yu, 2008;Zhao et al, 2015). WAS contains high levels of organic matter, which makes it a plentiful inexpensive source for SCFA production (Yuan et al, 2006;Wang et al, 2015).…”

The feasibility of enhanced biological phosphorus removal in the novel oxic/extended idle process using fermentation liquid from sludge fermentation

“…15 Further research conrmed that the enrichment mode and metabolic pathway of PAOs in the O/EI regime were signicant different from those in the traditional A/O process (e.g., a signicant idle release of phosphate and a low idle production of PHA). 16,17 Therefore, the new EBPR technology has broad application prospects.…”