Start-up of the anaerobic hydrolysis acidification (ANHA)- simultaneous partial nitrification, anammox and denitrification (SNAD)/enhanced biological phosphorus removal (EBPR) process for simultaneous nitrogen and phosphorus removal for domestic sewage treatment.

The simultaneous partial nitrification, anammox and denitrification (SNAD) process has been widely used in domestic sewage biological denitrification technology because of its high efficiency and low consumption. However, the simultaneous removal of another important pollution element, phosphorus, has been difficult, and its C/N ratio limitation of the influent is strict. The start-up of the anaerobic hydrolysis acidification (ANHA)- simultaneous partial nitrification, anammox and denitrification (SNAD)/enhanced biological phosphorus removal (EBPR) coupling process achieves the treatment of urban sewage for carbon, nitrogen and phosphorus removal. Under optimal conditions, the final total nitrogen and total phosphorus removal rates reached 91.59% and 89.10%, respectively. High-throughput sequencing technology showed that the ANHA reactor was mainly Lactococcus. At the same time, the main bacteria in the SNAD/EBPR process were anammox bacteria (AnAOB, Candidatus_Kuenenia, Candidatus_Brocadia) primarily existing in biofilms, while the ammonium oxidizing bacteria (AOB, Nitrosomonas), denitrifying polyphosphate-accumulating organisms (DPAOs, Pseudomonas, Flavobacterium, Bdellovibrio) and Denitrifying bacteria (DNB, Thauera, Denitratisoma, Rhodobacteraceae).were mainly found in the suspended sludge. These conclusions provide valuable information for the full-scale treatment of domestic sewage.

Operation adjustments of an electrochemically coupled system for total nitrogen removal and the associated mechanism.

A coupled system consisting of sequencing batch reactor and microbial fuel cell (SBR-MFC) was designed to buffer pH drift and purify wastewater. The addition of nitrifying sludge and the adjustment of hydraulic retention time (HRT) were performed to achieve better removal of total nitrogen (TN). When anaerobic/aerobic/anoxic phases in one cycle were 6/4/2 h, the removal efficiency of ammonium was 99.0 ± 1.3%, whereas denitrification was insufficient and the overall removal efficiency of TN was only 29.1 ± 5.8%. When the phases were adjusted to 6/2/4 h, the removal efficiencies of ammonium were 100.0 ± 0.0% in both closed and open circuits, and the overall removal efficiencies of TN were 91.4 ± 0.2% and 71.7 ± 4.2%, respectively, improved by 20% in MFC mode; the maximum voltage (200 Ω) maintained at 0.1 V. Ammonium-oxidizing bacteria (AOB) and Nitrite-oxidizing bacteria (NOB) in the sludge carried out nitrification. The main denitrification pathways in anoxic phase involved polyhydroxyalkanoate (PHA) denitrification by denitrifying glycogen accumulating organisms (GAOs) and electrochemical denitrification by electrochemical active bacteria (EAB). Few polyphosphate accumulating organisms (PAOs) were present, which accounted for poor P removal.

Spinel-based ceramic membranes coupling solid sludge recycling with oily wastewater treatment.

Highly efficient and economic treatment of wastewater sludges and wastewaters in one way is a challenging issue in the water treatment field. Herein we present a waste-to-resource strategy for rational fabrication of low-cost ceramic membranes, which simultaneously addresses the treatment of heavy metal-laden sludges and the separation of oil-in-water (O/W) emulsions. A thermal conversion mechanism is proposed for complicated reactions between simulated nickel-laden wastewater sludge and bauxite mineral. In addition to full stabilization and recycling of heavy metal wastewater sludges, rational tailoring of ceramic membrane structures can also be realized to achieve high water flux and favorable mechanical and surface properties. With rational structure design, the tailored spinel-based ceramic membranes exhibited high rejection and high flux (7473 LMH·bar-1) simultaneously for separation of oily wastewater, outperforming other reported state-of-the-art ceramic membranes. The membrane fouling mechanism revealed the dominance of cake layer formation at low cross flow velocities, while a combined model of cake layer formation and pore blocking dominated membrane fouling at high cross-flow velocities. The proposed strategy can be potentially extended toward design of functional ceramic membranes derived from other heavy metal wastewater sludges and for other water treatment applications.

Achieving mainstream nitrogen and phosphorus removal through Simultaneous partial Nitrification, Anammox, Denitrification, and Denitrifying Phosphorus Removal (SNADPR) process in a single-tank integrative reactor.

Simultaneous partial Nitrification, Anammox, and Denitrification (SNAD) is a promising and energy-efficient nitrogen removal process, which is powerless to eliminate phosphorus and confronted the problem of excessive effluent nitrate once applied in municipal sewage treatment characterized with high C/N ratio (≥2). Herein, by coupling SNAD with denitrifying phosphorus removal (DPR) process in a single-tank reactor, a novel integrative process (termed as SNADPR) was designed to treat municipal sewage. The removal efficiencies of TN, PO43--P, and COD under the optimized conditions (T = 30 °C, HRT = 24 h, DO = 0.45 mg/L) were 89.15 ±â€¯2.19%, 92.93 ±â€¯0.60%, and 99.17 ±â€¯1.58%, respectively. Distinctive microbial community distribution was harvested, where anammox bacteria (AnAOB, Candidatus_Kuenenia and Candidatus_Brocadia) were mainly located in biofilm, whereas denitrifying polyphosphate-accumulating organisms (DPAOs, Dechloromonas and Pseudomonas) and ammonium oxidizing bacteria (AOB, Nitrosomonas) basically lived in suspended floc. The SRT separation between biofilm and floc was reached by conserving AnAOB-rich biofilm and termly discharging phosphorus-rich floc.

Nitric oxide removal from flue gas with ammonium using AnammoxDeNOx process and its application in municipal sewage treatment.

A novel AnammoxDeNOx process was designed to simultaneously remove NOx in flue gas and ammonium wastewater, with the aim of exploring the possibility of using NO as a long-term and stable electron acceptor for anammox bacteria. The performance of the AnammoxDeNOx process indicated a NOx removal efficiency from simulated flue gas (including CO2, SO2, O2 and NO2) of 87-96% using simulated ammonium wastewater. With municipal wastewater, the removal efficiencies for NOx were 70-90%, total nitrogen 40-70%, and COD 80-90% (NO concentration: 100-500 ppm). The anammox genus underwent considerable changes from the dominant Candidatus Kuenenia in the stage of domestication to the predominant Candidatus Brocadia, which then became the dominant species in the simulated flue gas and actual municipal wastewater stages.

Granulation of Non-filamentous Bulking Sludge Directed by pH, ORP and DO in an Anaerobic/Aerobic/Anoxic SBR.

In an anaerobic/aerobic/anoxic (A/O/A) sequencing batch reactor (SBR), non-filamentous bulking sludge granulated after the adjustment of cycle duration and influent composition directed by pH, oxidation-reduction potential (ORP) and dissolved oxygen (DO). The turning points and plateaux of pH, ORP and DO profiles indicated the end of biochemical reactions, such as chemical oxygen demand (COD) consumption, P release, ammonium oxidation, P uptake and denitrification. The difference of nutrient concentration between the beginning and turning points represented the actual treatment capability of the sludge. Non-filamentous bulking with SVI30 of 255 mL g(-1) resulted in a huge biomass loss. After regulation, the cycle duration was shortened from 310 to 195 min without unnecessary energy input. In addition, the settling ability was obviously improved as SVI30 reduced to 28 mL g(-1). Moreover, matured granules with an average diameter of 600 µm were obtained after 45 days, and simultaneous COD, ammonium and phosphate (P) removal was also realized after granulation.

Optimal cultivation of simultaneous ammonium and phosphorus removal aerobic granular sludge in A/O/A sequencing batch reactor and the assessment of functional organisms.

In this study, sequencing batch reactor (SBR) with an anaerobic/aerobic/anoxic operating mode was used to culture granular sludge. Optimal adjustment of cycle duration was achieved by the direction ofpH, oxidation reduction potential and dissolved oxygen parameters. The results showed that the treating efficiency was significantly improved as the cycle was shortened from 450 to 360 min and further to 200 min. Nitrogen and phosphorus removal were nearly quantitative after 50 days operation and maintained stable to the end of the study period. The typical cycle tests revealed that simultaneous denitrification and phosphorus removal occurred when aerobic granules were gradually formed. The nitrite effect tests showed that less than 4.8 mg N/L of the nitrite could enhance superficial specific aerobic phosphate uptake rate (SAPUR) under aerobic condition, indicating that the traditional method to evaluate the capability of total phosphate-accumulating organisms (PAOs) was inaccurate. Additionally, a high level of nitrite was detrimental to PAOs. A novel method was developed to determine the activity of each kind of PAOs and other denitrifying organisms. The results showed that (1) nitrate, besides nitrite, could also enhance SAPUR and (2) aerobic granular sludge could perform denitrification even when phosphate was not supplied under anoxic condition, suggesting that other denitrifying organisms besides denitrifying phosphate-accumulating organisms also contributed to denitrification.

Hydrophobic modification of polyurethane foam for oil spill cleanup.

To improve the oleophilic/hydrophobic properties of polyurethane (PU) foams for oil spill cleanup, PU samples were modified by grafting with oleophilic monomer Lauryl methacrylate (LMA) in solvent and/or coating with LMA microspheres through heating and curing. Modified PU cubes were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). The water sorption of modified PU cubes was decreased by 24-50%, while the diesel or kerosene sorption of modified PU cubes was increased by 18-27%. In water-oil system, compared with blank PU cubes, the sorption capacity of PU cubes grafted with LMA was increased by 44% for diesel and 100% for kerosene. The sorption capacity of PU cubes coated with LMA microspheres was increased by 20% for diesel and 7% for kerosene. The solvent sorption of modified PU cubes could reach 50-69 g/g. The modified PU cubes can be effectively used in oil/solvent spill cleanup.

[Effect of aeration intensity on the nitrogen and phosphorus removal performance of AOA membrane bioreactors].

The ability of simultaneous phosphorus and nitrogen removal of sequencing batch membrane bioreactor run in anaerobic/oxic/ anoxic mode (AOA MBR) was examined under three aeration intensities [2.5, 3.75 and 5.0 m3 x (m2 x h)(-10]. The results showed that the averaged removals of COD were over 90% at different aeration intensities. And the higher aeration intensity was, the more ammonia nitrogen removal rate achieved. The removal rates of NH4(+) under the three aeration intensities were 84.7%, 90.6% and 93.8%, respectively. Total nitrogen removal rate increased with the increasing aeration intensity. But excessive aeration intensity reduced TN removal. The removal rates of TN under the three aeration intensities were 83.4%, 87.4% and 80.6%, respectively. Aeration intensity affected the denitrifying phosphorus ability of the AOA MBR. The ratio of denitrification phosphorus removal under the three aeration intensities were 20%, 30.2% and 26.7%, respectively.

Simultaneous nitrogen and phosphorus removal by a novel sequencing batch moving bed membrane bioreactor for wastewater treatment.

Biological nutrient removal (BNR) was investigated in a sequencing batch membrane bioreactor which used carriers instead of activated sludge named a sequencing batch moving bed membrane bioreactor (SBMBMBR). The SBMBMBR performed well on carbon and nitrogen removal at different COD/TN ratios. COD, TN and ammonium nitrogen removal efficiencies averaged at 93.5%, 82.6% and 95.6%, respectively. The TP removal was closely correlated with the length of anaerobic phase and aerobic phase. When anaerobic time and aerobic time were both 2h, the average TP removal efficiency reached to 84.1% at influent TP concentration of 12.4 mg/L. DO in aerobic phase was an important factor affecting nutrient removal, and the optimal DO was about 3mg/L. There was a small amount of denitrifying phosphorus accumulating organisms (DPAOs) in SBMBMBR which resulted from the anoxic microenvironment existed in the inner of the biofilm. Fluorescence in situ hybridization (FISH) results of microbes showed the composition and spatial structure of the microbial community in the reactor. Furthermore, sequencing batch mode operation was propitious to retard membrane fouling.

[Denitrifying phosphorus removal in MUCT-MBR].

The self-designed MUCT-MBR simplifies the MUCT process with reducing reactors from 5 to 2, which greatly reduces land occupied by equipment. Instead of secondary sedimentation tank, the membrane effluent quality is quite safe, and the operation is simple. In the investigation about simultaneous phosphorus and nitrogen removal of MUCT-MBR, the results showed that: when the proportions of C, N and P in the influent were 33.3/5/1-25/5.5/1, the average removal rate of COD, TN and TP in the whole experimental process were 89.3%, 75.4% and 79.2%, respectively. And the sludge settling capacity had no influence on the membrane effluent quality. The key factor of N and P removal rates is denitrifying phosphorus removal in anoxic condition. The proportion of denitrifying phosphate accumulating organisms (DPAOs) and the rate of denitrifying phosphorous removal were 84.2% and 67.07% on the 58th day, respectively.

Control of COD/N ratio for nutrient removal in a modified membrane bioreactor (MBR) treating high strength wastewater.

A modified membrane bioreactor (MBR) system has been developed to evaluate the efficiency of nutrient removal in treating synthetic high strength water. This study examined the effect of influent COD/N ratio on this system. Results showed that above 95.0% removal efficiencies of organic matter were achieved; indicating COD removal was irrespective of COD/N ratio. The average removal efficiencies of total nitrogen (TN) and phosphate (PO(4)(3-)-P) with a COD/N ratio of 9.3 were the highest at 90.6% and 90.5%, respectively. Furthermore, TN removal was primarily based on simultaneous nitrification and denitrification (SND) process occurred in the aerobic zone. Decreased COD/N ratios to 7.0 and 5.3, TN removal efficiencies in steady-states were 69.3% and 71.2%, respectively. Both aerobic SND and conventional biological nitrification/denitrification contributed to nitrogen removal and the latter played dominant effect. PO(4)(3-)-P-release and uptake process ceased in steady-states of COD/N 7.0 and 5.3, which decreased its removal efficiency significantly.

[Enrichment of denitrifying phosphate accumulating organisms in sequencing batch membrane bioreactors].

The enrichment and characteristics of denitrifying phosphate accumulating organisms (DPAO), which are capable of utilizing nitrate as electron acceptor, was investigated in a laboratory-scale sequencing batch membrane bioreactors (SBMBR). The results demonstrated that the proportion of DPAO increased from 19.4% to 69.6% of total phosphate accumulating organisms after anaerobic-aerobic and anaerobic-anoxic-aerobic phases. SBMBR system could operate steadily when 120 mg nitrate was added continuously during the anoxic phase every period. Simultaneous phosphate uptake and biological denitrification with good performance could be obtained in SBMBR operated in steady-state. Nitrate and phosphorus removal efficiency were above 100% and 84% respectively during anoxic phase, however, the effluent TP concentration was low than 0.5 mg/L, the total phosphorus removal efficiency was 96.1%. Furthermore, the ammonium nitrogen removal efficiency of SBMBR could be maintained at 92.2%, and the cumulation of nitrite and nitrate was not observed clearly.

[Comparisons of simultaneous phosphorus and nitrogen removal in sequencing batch membrane bioreactors].

Two SBMBRs run in AO and A2O mode were operated in parallel to compare their ability of simultaneous phosphorus and nitrogen removal. The results showed that the removals of COD and ammonium nitrogen were averaged over 90% and 95%, respectively. A2O MBR has the stronger anaerobic phosphorus release ability; its SPRR30 outdoes 47.5% compared to AO MBR. SPUR30 of A2O MBR was lower which may attribute to the higher effluent TP content. The ratio of DPAO was enhanced 57% compared to AO MBR. And when nitrate as the only electron accepter, the phosphorus uptake mass with unit electron transfer was 30% higher in A2O MBR. This two factors lead to the stronger denitrifying phosphorus removal ability of A2O MBR. Furthermore, the membrane fouling was mitigated in A2O MBR though the aerobic time was half to that of AO MBR. The membrane filter function made SBMBR's effluent free of the sludge settlement ability.