Intensifying the simultaneous removal of nitrogen and phosphorus of an integrated aerobic granular sludge-membrane bioreactor by Acinetobacter junii.

This work aims at intensifying the simultaneous removal of nitrogen and phosphorus of an integrated aerobic granular sludge (AGS) - membrane bioreactor (MBR) by Acinetobacter junii. After acclimation and enrichment in a sequencing batch reactor (SBR), Acinetobacter junii, a kind of denitrifying phosphate accumulating organism (DPAO), was successfully screened in the used SBR. Then it was verified to be capable of effectively enhancing the performance in the simultaneous removal of nitrogen and phosphorus of AGS-MBR. In the system, DPAO (Acinetobacter junii) mainly occurred in AGS, and the highest ratio even reached 22.8%, but its competitive advantages highly depend on the size of AGS. The presented results can cultivate AGS and enrich DPAO simultaneously to improve the removal of nitrogen and phosphorus of an AGS-MBR, which provide an environmentally friendly approach to upgrade traditional wastewater treatment processes.

Microbial driving mechanism for simultaneous removal of nitrogen and phosphorus in a pure anammox reactor under ferrous ion exposure.

The mechanisms of Fe2+ on nitrogen and phosphorus removal and functional bacterial competition in anammox systems was investigated. Under 0.12 mM Fe2+, the performance of nitrogen and phosphorus removal increased by 10.08 % and 151.91 %, respectively, compared with the control stage. Phosphorus removal was achieved through extracellular polymeric substance (EPS) induced biomineralization to form Fe-P minerals, and functional group COC in EPS played a critical role. T-EPSs was the major nucleation site due to it maintaining the supersaturated state (saturation index > 0) of Fe-P minerals for a long time. Population succession showed that Fe2+ weakened the competition between heterotrophic denitrifier (Denitrasoma) and anammox microbe (Candidatus Brocadia) for space and substrates, which was favorable for the enrichment of anammox biomass. Moreover, the variation in gene abundance (such as Hao, Cyt c, and Nir) indicated that Fe2+ improved electron behaviors (generation, transport, and consumption) during the nitrogen metabolism of anammox systems.

An efficient way to achieve stable and high-rate ferrous ion-dependent nitrate removal (FeNiR): Batch sludge replacement.

Ferrous ion can be used as electron donor for denitrification in the ferrous ion-dependent nitrate removal (FeNiR). To prevent the FeNiR performance decrease caused by iron encrustation, a modified FeNiR process with batch sludge replacement was developed. Based on the decay kinetics of sludge mass and sludge activity, the sludge retention time (SRT) was determined as 40 days in the modified FeNiR process. To keep the FeNiR rate at 0.70 kg-N/(m3·d), the sludge replacement amount was 25% of total sludge every 10 days. The FeNiR efficiency stabilized around 70%. The batch sludge replacement could be an effective method to offset the active sludge decay caused by iron encrustation, and therefore led to the good FeNiR performance. The wasted FeNiR sludge was found to adsorb phosphate at a rate of 0.9 mg-P/(g VS min). The modified FeNiR process was proposed to be coupled with phosphate removal, achieving the co-removal of nitrate and phosphate. The coupled technology is promising due to the less consumption of resources and energy, as well as the less production of excessive sludge.

Use of autoclaved aerated concrete particles for simultaneous removal of nitrogen and phosphorus as filter media from domestic wastewater.

ABSTRACT In this study, autoclaved aerated concrete particles (AACPs) from construction waste were used to simultaneously remove phosphorus and nitrogen in biological aerated filters (BAFs). The effects of air/water (A/W) ratio on the removal performance of phosphorus (PO4 3-), total organic carbon, total nitrogen (TN), and ammonia nitrogen were investigated. Results showed that AACP BAF was more efficient than commercially available ceramsite (CAC) BAF. For example, the removal rates of TN with AACP and CAC were 45.96% and 15.64%, respectively, and those of PO4 3- with AACP and CAC were 72.45% and 33.97%, respectively, at the A/W ratio of 3:1. Different characterization methods were utilized to evaluate the surface shape, elemental compostion, and internal and surface structure of AACP. The interconnectivity and uniformity of pores and the rough surface of AACP were found to be suitable for the growth of microbial biofilm. In addition, the growth of internal pores in AACP promoted the removal of phosphorus and nitrogen. The surface of used AACP contained a small amount of irregular crystals and was covered with a layer of aggregates, which were characterized as hydroxyapatite [HAP, Ca5(OH)(PO4)3]. The formation of HAP as a final byproduct confirmed the successful removal of phosphorus. Therefore, construction wastes, such as AACPs, could be recycled and utilized as a promising biofilter media for excellent wastewater treatment.

Remoção simultânea de material orgânico, nitrogênio e fósforo em um reator em bateladas sequenciais com biofilme de leito móvel operado pelo processo anaeróbio-anóxico-óxico / Simultaneous removal of organic material, nitrogen and phosphorus in a reactor in batches of mobile bed biofilm sequencing by the anaerobic-anoxic-oxic process

RESUMO Neste estudo, foi avaliado o desempenho de um reator em bateladas sequenciais com biofilme de leito móvel operado pelo processo anaeróbio-anóxico-óxico (A2O), aplicado à remoção simultânea de material orgânico, nitrogênio e fósforo de esgoto sanitário. Utilizaram-se dois reatores com volume útil de 36 L cada, sendo que um deles recebeu anéis plásticos móveis do tipo Kaldnes®, com área superficial específica estimada em 310 m2/m3 que ocuparam 50% do volume útil do reator (denominado aqui de MBSBBR). O estudo foi conduzido com tempo de retenção de sólidos (TRS) de 12 dias, tempo de retenção hidráulico (TRH) de 6 horas, taxa de alimento/microrganismo (A/M) de 0,4 a 0,5 gDQO/SSV.d, oxigênio dissolvido (OD) na faixa de 0,3-0,8 mgO2/L e taxas de aplicação de carga orgânica, nitrogênio e fósforo de 47,2 gDQO/L.d, 5,4 gNTK/L.d e 0,4 gP/L.d, respectivamente. Os resultados de eficiência de remoção de demanda química de oxigênio (DQO), N-NH3 e fósforo foram de 91,1, 90,5 e 85,4% para o reator MBSBBR e de 89,5, 91,6 e 84,4% para o reator RBS, respectivamente. Os resultados do teste estatístico de ANOVA foram aplicados às principais variáveis estudadas, e os valores convergiram para valores de f observado < f crítico . Dessa forma, considera-se que houve similaridade de desempenho nos reatores MBSBBR e RBS. Conclui-se que a introdução do meio suporte não trouxe benefícios ao tratamento em termos de remoção de nutrientes. No entanto, o estudo mostrou que é possível de se obter elevada remoção de nitrogênio, em baixas concentrações de OD, o que se torna vantajoso para o tratamento de esgoto com elevada concentração de nitrogênio.

ABSTRACT In this study, the performance of a reactor in sequential batch with mobile bed biofilm operated by the anaerobic-anoxic-oxic (A2O) process, applied to the simultaneous removal of organic material, nitrogen and phosphorus from sanitary sewage was evaluated. Two reactors with a useful volume of 36 liters each were used, one of them receiving Kaldnes® type mobile plastic rings, with a specific surface area estimated at 310 m2/m3, which occupied 50% of the reactor's useful volume (MBSBBR). The study was conducted with 12-day solid retention time (SRT), 6 hour hydraulic retention time (HRT), food/microorganism (F/M) ratio of 0.4 to 0.5 gCOD/VSS.d, dissolved oxygen (DO) in the range of 0.3-0.8 mgO2/L and application rates of organic load, nitrogen and phosphorus of 47.2 gCOD/L.d, 5.4 gTNK/L.d and 0.4 gP/L.d, respectively. The efficiency of chemical oxygen demand (COD), N-NH3 and Phosphorus removal was of 91.1%, 90.5% and 85.4% for the MBSBBR reactor and 89.5%, 91.6% and 84.4% for the RBS reactor, respectively. The results of the statistical ANOVA test were applied to the main variables studied and the values converged to values of f observed < f critical . In this way, it is considered that there was a similarity of performance between the MBSBBR and RBS reactors. It is concluded that the introduction of the support medium did not bring benefits to the treatment in terms of nutrient removal. However, the study showed that it is possible to obtain high nitrogen removal at low concentrations of DO, which is advantageous for the sewage treatment with high nitrogen concentration.

[Combined Process of DNBF-O3-GAC for Nitrogen and Phosphorus and Metabolite Advanced Removal].

To improve the quality of the tailings water from a wastewater treatment plant (WWTP), a denitrification biofilter (DNBF) with a composite filler composed of a new slow-release organic-carbon source (SOC-F), sponge iron, and activated carbon was tested. Studies were conducted in the combined process of DNBF-O3-GAC to explore the efficiency of the advanced removal of nitrogen, phosphorus, and microbial metabolite by using synthetic effluent made from running water and chemicals. Corresponding comparative studies were conducted by using the secondary effluent from the WWTP. The microbial population structure in the biofilm of the denitrification biofilter was analyzed by adopting MiSeq high-throughput sequencing technologies. The results indicated that the combination process achieved high efficiency removal of nitrogen, phosphorus, and microbial metabolite. The average removal rate of NO3--N in the simulated and actual water period reached 88.87% and 79.99%, respectively; the average removal rate of TP reached 87.67% and 65.51%, respectively; and the average removal rate of UV254 reached 45.51% and 49.23%, respectively. Each processing unit had different functions. The changes in NO3--N, TN, TP, and TFe mainly occurred in the denitrification biofilter, and the removal of UV254 and the change in the three-dimensional fluorescence intensity mainly occurred in the ozone-activated carbon reactor. The cluster analysis at the genus level indicated that the denitrification system had sulfur autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria. Sulfur autotrophic denitrification increased obviously in the actual water period when relatively lack of carbon sources, and the proportion of Thiobacillus increased from 7.44% to 29.62%. The complementary effect of sulfur autotrophic denitrification and heterotrophic denitrification had extended the use of the new slow-release carbon source.