[Start-up of an Integrated Process of Denitrifying Phosphorus Removal Coupled with Partial Nitritation and Anaerobic Ammonium Oxidation].

An integrated process uses an anaerobic baffled reactor combined with a fully mixed reactor (ABR-CSTR) as a test carrier for low-carbon, high-ammonia nitrogen (NH4+-N ≥ 200 mg·L-1) wastewater under continuous flow operating conditions; the normal anaerobic sludge in different compartments is subjected to domestication and cultivation to realize denitrifying phosphorus removal, partial nitritation, and anaerobic ammonium oxidation, thereby achieving the coupling effect of the three. Partial nitritation was successfully achieved in the A4 (CSTR) section by the strategy of limited oxygen (dissolved oxygen DO=0.8 mg·L-1) and intermittent aeration (exposure ratio=30 min:30 min) after 30 days. Subsequently, a strategy of shortening the hydraulic retention time (HRT) was adopted to achieve a stable operation of partial nitritation, and a stable influent substrate of NO2--N/NH4+-N 1.0-1.1 was provided for anaerobic ammonium oxidation. The anaerobic ammonium oxidation function was achieved after 154 days in the A5 and A6 compartments. The removal rates of NH4+-N and NO2--N were 94% and 97%, respectively, and the NO3--N concentration in the effluent was stable at 22 mg·L-1. The denitrifying phosphorus removal function was successfully achieved in the A1-A3 compartments by using NOx--N in the reflux as an electron acceptor. The removal rate of PO43--P was 77%. The integrated process was successfully coupled through 175 days, achieving simultaneous removal of C, N, and P.

[ABR Decarbonization-Nitrosation Coupled with ANAMMOX to Treat Municipal Wastewater].

In order to promote the application of anaerobic ammonium oxidation (ANAMMOX) to treat municipal wastewater, nitrosation was coupled with ANAMMOX and an ABR decarbonization system at the front of it; then used to build a system in which ABR decarbonization-nitrosation coupled with ANAMMOX was used to treat municipal wastewater. The high throughput sequencing technology of MiSeq was employed to analyze the structure of the microbial community in the sludge. Results showed that the average effluent COD concentration of the carbon removal system was 120 mg·L-1 and that the subsequent nitrosation system and ANAMMOX system would not be adversely affected by the effluent COD. Controlled by matching the nitrosation effluent with that from the ABR carbon removal system 2:1, the ANAMMOX influent, kept the ratio of the NO2--N and NH4+-N matrix to ANAMMOX at about 1:1. The total nitrogen removal rate of the integrated reactor was 86%-92% and the COD of the effluent was 20-40 mg·L-1. After the experiment, the number of bacteria in class γ-Proteobacteria in the nitrosation system, which are closely related to denitrification, increased. Members of class Sphingobacteria, which have the function of enhancing the growth rate of microorganisms and enhancing the rate of denitrification, were significantly increased in the ANAMMOX system. The nitrogen and carbon in the municipal wastewater could be stably and efficiently removed by the ABR Decarbonization-Nitrosation coupled with ANAMMOX process.

[Carbon and Nitrogen Removal Characteristics of ABR Decarbonization-CANON Coupling Process].

If municipal wastewater can be treated by the completely autotrophic nitrogen removal over nitrite (CANON) process, it will greatly reduce the energy consumption of municipal wastewater treatment. The CANON reactor with a fiber carrier was started up by seeding nitrosation sludge and anaerobic ammonia oxidation (ANAMMOX) sludge in the continuously stirred tank reactor (CSTR). An ABR decarbonization system was added to the front of the CANON system to build the ABR decarbonization-CANON coupling process to examine carbon and nitrogen removal characteristics of the whole system. The high throughput sequencing technology of MiSeq was also employed to analyze the structure of the microbial community before and after the reactivation. The results showed that mixing nitrosation sludge and ANAMMOX sludge in the CSTR reactor under controlled parameters (DO of 0.5-2 mg·L-1; HRT for 6 h; pH of 8) allowed the CANON system to successfully start within 55 d, with a TN removal rate of 81%-87% and ammonia nitrogen load of 0.195 kg·(m3·d)-1. The effluent COD concentration of the ABR decarbonizing system did not adversely affect the subsequent CANON system, and the TN removal rate of the ABR decarbonization-CANON process was between 74% and 87%. Additionally, the average concentration of COD in the effluent was 40 mg·L-1. At the same time, the Proteobacteria gate significantly improved after the CANON system began, and the proportion of Sphingobacteria decreased to 6.8%. Nitrifying bacteria and anaerobic ammonia oxidizing bacteria in the CANON system continuously eliminated the inferior bacterial groups to become the dominant group in the reactor. The integrated ABR decarbonization-CANON process had a positive effect on the denitrification and decarbonization of urban sewage.

[Reactivation Performance of Nitrosation Flocculent Sludge After Long-term Storage].

In order to explore the nitrogen removal performance of nitrosation flocculent sludge subject to long-term storage, nitrosation flocculent sludge which had been stored at 4℃ for ten months was inoculated in a continuous stirred tank reactor (CSTR) to investigate its activity recovery performance. MiSeq high throughput sequencing technology was also employed to analyze the structure of the microbial community before and after reactivation. Results showed that, under DO control of DO 0.4-0.8 mg·L-1, pH value of about 8 and temperature of (30±1)℃, the sludge could be reactivated in 15 days. Both the removal efficiency of ammonia nitrogen and the accumulation ratio of nitrite nitrogen were higher than 90%. The color of the sludge quickly changed from grey at early inoculation to brown, while the sludge volume index (SVI) quickly decreased and both mixed liquor volatile suspended solids (MLVSS)/mixed liquor suspended solids (MLSS) and extracellular polymer substances (EPS) significantly increased. With the recovery of nitrosation performance, anaerobic and heterotrophic bacteria were washed out, the relative abundance of ammomia-oxidizing bacteria such as Nitrosomonas significantly increased, while the growth of nitrite-oxidizing bacteria such as Nitrospria was selectively inhibited. Nitrosation flocculent sludge could be inoculated after long-term storage to achieve rapid start-up of partial nitrification and allow practical application of partial nitrification processes.

[Quick Start-up and Sustaining of Shortcut Nitrification in Continuous Flow Reactor].

How to achieve fast and stable startup of shortcut nitrification has a very important practical value for treatment of low C/N ratio wastewater. Thus, the quick start-up and sustaining of shortcut nitrification were investigated in continuous flow reactor targeting at the current situation of urban wastewater treatment plant using a continuous flow process. The results showed that quick start-up of shortcut nitrification could be successfully achieved in a continuous flow reactor after 60 days' operation with intermittent aeration and controlling of three stages of stop/aeration time (15 min/45 min, 45 min/45 min and 30 min/30 min). The nitrification rates could reach 90% or 95% respectively, while influent ammonia concentrations were 50 or 100 mg · L⁻¹ with stop/aeration time of 30 min/30 min. In addition, intermittent aeration could inhibit the activity of nitrite oxidizing bacteria (NOB), while short hydraulic retention time (HRT) may wash out NOB. And a combined use of both measures was beneficial to sustain shortcut nitrification.

[Nitrogen Removal of Municipal Wastewater by ANAMMOX Coupled Shortcut Nitrification in Anaerobic Baffled Reactor].

If the technology of anaerobic ammonium oxidation(ANAMMOX) can substitute the mainstream technology of municipal wastewater treatment plant, the energy of municipal wastewater treatment will be decreased significantly. Thus, anaerobic baffled reactor(ABR) was used to build carbon system, shortcut nitrification system and anaerobic ammonia oxidation system. And the three systems were coupled to shortcut nitrification-anaerobic ammonia oxidation reactor to treat municipal wastewater. The results showed that the average effluent COD concentration of carbon removal system was 80 mg·L-1 when the hydraulic retention time of carbon removal system was 4.5 h. And the subsequent shortcut nitrification system would not be adversely affected by the effluent COD. Finally, the average effluent total nitrogen concentration was 10 mg·L-1, with total nitrogen volume load of ANAMMOX system of 0.36 kg·(m3·d)-1. When the dissolved oxygen was controlled between 1 to 2 mg·L-1, the nitrite accumulation rate could be maintained around 90%, ensuring the stable operation of the subsequent anaerobic ammonia oxidation system. The nitrogen of municipal wastewater could be stable and efficiently removed by the shortcut nitrification -ANAMMOX integration ABR with temperature of 30℃ and dissolved oxygen of 1-2 mg·L-1.

[Nitrogen Removal Using ANAMMOX and Denitrification for Treatment of Municipal Sewage].

In this study, an Anaerobic Baffled Reactor ( ABR) was constructed. The ANAMMOX process was successfully started up using this reactor within 45 days under the following condition: 27 degrees C, pH of 8, HRT of 10 h, and the influent NO2(-) -N/NH4(+) -N was 1.32. At the stable phase, the average TN removal percentages reached 83% and the ΔNH4(+) -N: ΔNO2(-) -N: ΔNO3(-) -N was 1 : 1. 31 : 0.27. In the process of treating municipal sewage, there was inevitably a certain amount of organic carbon in the influent. Organic carbon had no obvious effect on the ANAMMOX process at C/N of 0.5; Nitrogen removal was improved, and the average total nitrogen (TN, including ammonia, nitrite and nitrate nitrogen) removal efficiency of 93% was obtained at C/N of 1. However, at C/N of 2, the TN removal performance reduced due to the suppression of ANAMMOX by organic carbon; the ANAMMOX bacteria could recover their activity in a short period of time by reducing the influent COD concentration. In this work, the performance of the ANAMMOX-denitrification process in the treatment of municipal sewage was investigated, which proved the suitability of ABR-denitrification reactor in treating municipal sewage with low ammonia nitrogen concentration, with an effluent TN concentration of 7.5 mg x L(-1), and the average TN removal percentages reaching 86%.