Development of physicochemical nitrogen removal process for high strength industrial wastewater

The biological nitrogen removal (BNR) process is the most common method for removing low quantities of ammonium from wastewater, but this method is not used for wastewater rich with ammonium. In this study, we have developed the physicochemical nitrogen removal process to remove the nitrogen content for a real industrial wastewater. The denitrification was accomplished by the physicochemical denitrification process using zinc powder and sulfamic acid in pH 2-4. The experimental parameters were examined by varying various reaction conditions such as pH, zinc feeding time, amount of sulfamic acid, and amount of nitrate concentration. For each experimental condition, the physicochemical denitrification process was determined by pH, amount of zinc powder and sulfamic acid, zinc feeding time and nitrate concentration.     

城市污水脱氮除磷技术与展望

介绍了国内外城市污水的脱氮除磷现状,探讨了城市污水脱氮除磷技术的发展趋势,同时提出较为高效、经济且资源化的城市污水脱氮除磷工艺,对城市污水脱氮除磷技术的发展进行了展望。     

高氨氮城市污水脱氮的运行及讨论

针对厦门大学污水厂水质特点,分析了污水高含氮量的原因,介绍了该污水厂在污水处理上采取的措施,提出了对现有工艺进行改造的建议,以提高污水脱氮效率,确保污水达标排放。     

Biological nitrogen removal of high-strength ammonium industrial wastewater with two-sludge system

The biological nitrogen removal (BNR) process is the most common method for removing low quantities of ammonium from wastewater, but this is not the usual treatment for high-strength ammonium wastewater. The capacity to biologically remove the nitrogen content of a real industrial wastewater with a concentration of 5000 g N-NH(4)(+) L(-1) is demonstrated in this work. The experimental system used is based on a two-sludge system, with a nitrifying activated sludge and a denitrifying activated sludge. This system treated real industrial wastewater for 450 days, and during this period, it showed the capacity for oxidizing all the ammonium at average nitrification rates between 0.11 and 0.18 g N-NH(4)(+)g VSS(-1)d(-1). Two key process parameters were evaluated: the maximum nitrification rate (MNR) and the maximum denitrification rate (MDR). MNR was determined in continuous operation at three different temperatures: 15 degrees C, 20 degrees C and 25 degrees C, obtaining values of 0.10, 0.21 and 0.37 g N-NH(4)(+) g VSS(-1)d(-1), respectively. Complete denitrification was achieved using two different industrial carbon sources, one containing mainly ethanol and the other one methanol. The MDR reached with ethanol (0.64 g N-NO(x)(-) g VSS(-1)d(-1)) was about 6 times higher than the MDR reached with methanol (0.11g N-NO(x)(-)g VSS(-1)d(-1)).     

A2/O脱氮除磷工艺

介绍了A2 /O脱氮除磷工艺的原理及特点 ,阐述了其工艺流程 ,针对A2 /O工艺存在的具体问题 ,提出了可行的改进措施 ,以提高其总体脱氮除磷效果     

Removal of organics and nutrients from food wastewater using combined thermophilic two-phase anaerobic digestion and shortcut biological nitrogen removal

A process combining pilot-scale two-phase anaerobic digestion and shortcut biological nitrogen removal (SBNR) was developed to treat organics and nutrients (nitrogen and phosphorus) from food wastewater. The thermophilic two-phase anaerobic digestion process was investigated without adjusting the pH of the wastewater for the pre-acidification process. The digested food wastewater was treated using the SBNR process without supplemental carbon sources or alkalinity. Under these circumstances, the combined system was able to remove about 99% of COD, 88% of TN, and 97% of TP. However, considerable amounts of nutrients were removed due to chemical precipitation processes between the anaerobic digestion and SBNR. The average TN removal efficiency of the SBNR process was about 74% at very low C/N (TCOD/TN) ratio of 2. The SBNR process removed about 39% of TP from the digested food wastewater. Conclusively, application of the combined system improved organic removal efficiency while producing valuable energy (biogas), removed nitrogen at a low C/N ratio, and conserved additional resources (carbon and alkalinity).     

Characteristics and fate of organic nitrogen in municipal biological nutrient removal wastewater treatment plants

The aim of this study was to investigate the occurrence and fate of colloidal and dissolved organic nitrogen (CON and DON) across biological nutrient removal (BNR) activated sludge bioreactors. Primary and secondary effluent total nitrogen (TN) measurements and component fractionation, CON and DON concentration profiles across BNR bioreactors, and laboratory batch experiments with the process mixed liquor were carried out at several full-scale BNR plants in northern Poland. The organic nitrogen (ON) components were divided into high CON, low CON, and DON based on sequential filtration through 1.2, 0.45 and 0.1 μm pore-size filters. The average influent DON_0.1μm (<0.1 μm) concentrations ranged from 1.1 g N/m³ to 3.9 g N/m³ and accounted for only 4-13% of total organic nitrogen. In the effluents, however, this contribution increased to 12-45% (the DON_0.1μm concentrations varied in a narrow range of 0.5-1.3 g N/m³). Conversions of ON inside the bioreactors were investigated in more detail in two largest plants, i.e. Gdansk (565,000 PE) and Gdynia (516,000 PE). Inside the two studied bioreactors, the largest reductions of the colloidal fraction were found to occur in the anaerobic and anoxic compartments, whereas an increase of DON_0.1μm concentrations was observed under aerobic conditions in the last compartment. Batch experiments with the process mixed liquor confirmed that DON_0.1μm was explicitly produced in the aerobic phase and significant amounts of ON were converted in the anoxic phase of the experiments.     

废水生物脱氮新工艺研究进展

对生物脱氮新工艺进行了较全面的综述,分析了影响NO2-N积累的主要因素为游离氨、pH值、温度、溶解氧、污泥龄和有害物质,主要介绍了短程硝化反硝化、厌氧氨氧化和CANON等生物脱氮新工艺的微生物学原理,研究应用现状、发展前景以及存在的问题。     

Energetics of single-sludge nitrogen removal

Energetic considerations were used to predict several parameters of the single sludge nitrogen removal system. Experimental results from bench-scale studies using a synthetic feed served to evaluate the proposed method. Based on observed sludge yields the energy utilization efficiency was estimated at 20 and 40% for heterotrophs and nitrifiers, respectively, at SRT ranging from 7 to 17 days. For a constant nitrogen/COD removal ratio of 0.14 the predicted nitrifiers fraction in the sludge was 0.077. Based on viable cell counts the nitrifiers fraction varied between 0.125 and 0.206 averaging 0.153. The calculated specific nitrification rate based on total nitrifiers mass ranged from 37 to 63 mg N g VSS⁻¹ h⁻¹ with an average of 46 mg N g VSS⁻¹ h⁻¹. Based on viable cells counts the specific activity was determined between 937 and 1660 mg N g VSS⁻¹ h⁻¹ with an average of 1219 mg N g VSS⁻¹ h⁻¹. Results of this study suggest the thermodynamic approach can be used successfully in determining several parameters of the single sludge process. However, its applicability to predict such parameters as nitrifiers fraction and specific nitrifraction rate is dependent on prior knowledge of the energy utilization efficiency and microbial viability.     

Ammonium nitrogen removal from coking wastewater by chemical precipitation recycle technology

Ammonium nitrogen removal from wastewater has been of considerable concern for several decades. In the present research, we examined chemical precipitation recycle technology (CPRT) for ammonium nitrogen removal from coking wastewater. The pyrolysate resulting from magnesium ammonium phosphate (MAP) pyrogenation in sodium hydroxide (NaOH) solution was recycled for ammonium nitrogen removal from coking wastewater. The objective of this study was to investigate the conditions for MAP pyrogenation and to characterize of MAP pyrolysate for its feasibility in recycling. Furthermore, MAP pyrolysate was characterized by scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) as well as X-ray diffraction (XRD). The MAP pyrolysate could be produced at the optimal condition of a hydroxyl (OH⁻) to ammonium molar ratio of 2:1, a heating temperature of 110 °C, and a heating time of 3 h. Surface characterization analysis indicated that the main component of the pyrolysate was amorphous magnesium sodium phosphate (MgNaPO₄). The pyrolysate could be recycled as a magnesium and phosphate source at an optimum pH of 9.5. When the recycle times were increased, the ammonium nitrogen removal ratio gradually decreased if the pyrolysate was used without supplementation. When the recycle times were increased, the ammonium nitrogen removal efficiency was not decreased if the added pyrolysate was supplemented with MgCl₂·6H₂O plus Na₂HPO₄·12H₂O during treatment. A high ammonium nitrogen removal ratio was obtained by using pre-formed MAP as seeding material.     

Application of response surface methodology for simultaneous carbon and nitrogen (SND) removal from dairy wastewater in batch systems

The application of batch systems to the direct treatment of dairy wastewater was investigated. Batch experiments were conducted to study the organics removal and simultaneous nitrification and denitrification (SND) process. The experiment was conducted by varying four independent parameters (mixed liquor suspended solids, chemical oxygen demand [COD]/N ratio, aeration time and cycling time), using a central composite design under response surface methodology. The process responses of five dependent parameters (COD, Total kjehldahl nitrogen (TKN), NO₃ ^?, effluent NO₃ ^? and effluent total nitrogen) were studied, and in each case, the percentage removal in batch runs was determined with each process displayed in contour plots. Finally, after optimizing the process conditions, the best treatment of dairy wastewater under optimized conditions was established and the responses were shown. This study shows that microbial granules cultivated under the alternating aerobic/anaerobic conditions in batch systems could efficiently remove organic carbon and convert all the ammonium to nitrogen gas.     

Alumina nanoparticles-induced effects on wastewater nitrogen and phosphorus removal after short-term and long-term exposure

Alumina nanoparticles (Al₂O₃ NPs) have been widely used in many fields, which causes a growing concern about their potential health and environmental risks. However, their possible impacts on wastewater nitrogen and phosphorus removal have not yet been reported. In this study, both short-term and long-term effects of Al₂O₃ NPs on wastewater nutrient removal were investigated. Scanning electron microscope (SEM) analysis showed that most of Al₂O₃ NPs were adsorbed onto activated sludge, but these NPs had no adverse effects on the surface integrity and viability of activated sludge. It was found that short-term exposure to 1 and 50 mg/L Al₂O₃ NPs induced marginal influences on wastewater nitrification, denitrification and phosphorus removal. Nevertheless, the prolonged exposure to 50 mg/L Al₂O₃ NPs was observed to decrease the total nitrogen (TN) removal efficiency from 80.4% to 62.5% due to the suppressed denitrification process, although biological phosphorus removal and the transformations of intracellular polyhydroxyalkanoates and glycogen were not affected. Quantitative PCR assays indicated that compared with the control, 50 mg/L Al₂O₃ NPs decreased the abundance of denitrifying bacteria in activated sludge. Further enzyme activity tests showed that the activities of key denitrifying enzymes (nitrate reductase and nitrite reductase) were inhibited, which might be responsible for the negative effects of 50 mg/L Al₂O₃ NPs on wastewater nitrogen removal after long-term exposure.     

Preliminary screening of small-scale domestic wastewater treatment systems for removal of pharmaceutical and personal care products

Occurrence and removal efficiencies of 13 pharmaceuticals and personal care products (PPCPs) as well as BOD₅, TSS and NH₄⁺ were evaluated for the first time in thirteen onsite household secondary wastewater treatment systems, including two compact biofilters followed by Filtralite-P filter units, two biological sand filters, five horizontal subsurface flow and four vertical flow constructed wetlands. As expected, all systems removed TSS and BOD₅ efficiently (>95% removal). The PPCP removal efficiencies exceeded 80% with the exception of carbamazepine, diclofenac and ketoprofen because of their more recalcitrant characteristics. Despite no statistical differences in the PPCP removal were observed between the different systems evaluated, the vegetated vertical flow constructed wetlands which had unsaturated flow and hence better oxygenation, appeared consistently to perform better in terms of PPCP removal efficiency. The combined effects of vegetation and unsaturated water flow provide a higher tolerance to variations in loading rate and a consistent removal rate.     

Treating wastewater from a pharmaceutical formulation facility by biological process and ozone

Wastewater from a pharmaceutical formulation facility (TevaKS, Israel) was treated with a biological activated-sludge system followed by ozonation. The goal was to reduce the concentrations of the drugs carbamazepine (CBZ) and venlafaxine (VLX) before discharging the wastewater to the municipal wastewater treatment plant (WWTP). Both drugs were detected at extremely high concentrations in TevaKS raw wastewater ([VLX] = 11.72 ± 2.2 mg/L, [CBZ] = 0.84 ± 0.19 mg/L), and resisted the biological treatment. Ozone efficiently degraded CBZ: at an O₃ dose-to-dissolved organic carbon ratio of 0.55 (O₃/DOC), the concentration of CBZ was reduced by >99%. A lower removal rate was observed for VLX, which was decreased by ～98% at the higher O₃/DOC ratio of 0.87. Decreasing the pH of the biologically treated effluent from 7 to 5 significantly increased the ozone degradation rate of CBZ, while decreasing the degradation rate of VLX. Ozone treatment did not alter the concentration of the effluent's DOC and filtered chemical oxygen demand (COD_f). However, a significant increase was recorded (following ozonation) in the effluent's biological oxygen demand (BOD₅) and the BOD₅/COD_f ratio. This implies an increase in the effluent's biodegradability, which is highly desirable if ozonation is followed by a domestic biological treatment. Different organic byproducts were formed following ozone reaction with the target pharmaceuticals and with the effluent organic matter; however, these byproducts are expected to be removed during biological treatment in the municipal WWTP.     

改进AB工艺强化脱氮运行实践与分析

通过将少量A曝混和液不经沉淀直接引入B曝对AB工艺进行改进,使设计不具备脱氮能力的AB工艺在较短HRT(好氧区HRT:3~3.7 h)内获得62%~81%的硝化效率,出水氨氮低于15 mg/l,但由于碳源不足等原因系统反硝化效率没有明显提高.将B段剩余污泥排到A段曝气池,系统剩余污泥完全由A段排出,可起到对A段微生物接种等作用,还可以预防污泥在重力浓缩池内因发生反硝化反应而导致污泥上浮的隐患,污泥浓缩和脱水性能更好.     

Enhanced ammonia nitrogen removal using consistent biological regeneration and ammonium exchange of zeolite in modified SBR process

The modified zeo-SBR is recommended for a new nitrogen removal process that has a special function of consistent ammonium exchange and bioregeneration of zeolite-floc. Three sets of sequencing batch reactors, control, zeo-SBR, and modified zeo-SBR were tested to assess nitrogen removal efficiency. The control reactor consisted of anoxic-fill, aeration-mixing, settling, and decanting/idle phases, meaning that nitrogen removal efficiency was dependent on the decanting volume in a cycle. The zeo-SBR reactor was operated in the same way as the control reactor, except for daily addition of powdered zeolite in the SBR reactor. The operating order sequences in the zeo-SBR were changed in the modified zeo-SBR. Anoxic-fill phase was followed by aeration-mixing phase in the zeo-SBR, while aeration-mixing phase was followed by anoxic-fill phase in the modified zeo-SBR to carry NH4(+)-N over to the next operational cycle and to reduce total nitrogen concentration in the effluent. In the modified zeo-SBR, nitrification and biological regeneration occurred during the initial aeration-mixing phase, while denitrification and ammonium adsorption occurred in the following anoxic-fill phase. The changed operational sequence in the modified zeo-SBR to adapt the ammonium adsorption and biological regeneration of the zeolite-floc could enhance nitrogen removal efficiency. As a result of the continuous operation, the nitrogen removal efficiencies of the control and zeo-SBR were in 68.5-70.9%, based on the 33% of decanting volume for a cycle. The zeo-SBR showed a consistent ammonium exchange and bio-regeneration in the anoxic-fill and aeration-mixing phases, respectively. Meanwhile, the effluent total nitrogen of the modified zeo-SBR showed 50-60 mg N/L through ammonium adsorption of the zeolite-floc when the influent ammonium concentration was 315 mg N/L, indicating the T-N removal efficiency was enhanced over 10% in the same HRT and SRT conditions as those of control and zeo-SBR reactors. The ammonium adsorption capacity was found to be 6-7 mg NH4(+)-N/g FSS that is equivalent to 40 mg NH4(+)-N/L of ammonium nitrogen removal.     

Single sludge nitrogen removal in an oxidation ditch

Activated sludge systems of the oxidation ditch configuration are uniquely suitable for the single-sludge nitrification and denitrification process. This is due to the high recycle flow generated by the aeration system. Existing systems, originally designed for carbonaceous organic removal and nitrification, can be modified to the complete nitrogen removal mode, through the control of oxygen supply. This paper discusses the conditions required for such modification along with the necessary calculation procedures. A case study of a full-scale industrial plant is presented. Calculations based on the principles outlined herein illustrate the capability of the existing system to operate successfully under the single-sludge mode. Actual data over a 15 months period support these results.     

Development of a 2-sludge, 3-stage system for nitrogen and phosphorous removal from nutrient-rich wastewater using granular sludge and biofilms

A novel 2-sludge 3-stage process using a combination of granular sludge and biofilm was developed to achieve biological removal of nitrogen and phosphorus from nutrient-rich wastewater. The system consists of a granular sequencing batch reactor (SBR) working under alternating anaerobic/anoxic conditions supplemented with a short aerobic phase and an aerobic biofilm SBR. The wastewater is first fed to the granular SBR reactor, where easily biodegradable carbon sources are taken up primarily by polyphosphate accumulating organisms (PAOs). The supernatant resulting from quick settling of the granular sludge is then fed to the biofilm SBR for nitrification, which produces oxidized nitrogen that is returned to the granular reactor for simultaneous denitrification and phosphorus removal. While maximizing the utilization of organic substrates and reducing operational costs, as do other 2-sludge processes previously reported in literature, the proposed system solves the bottleneck problem of traditional 2-sludge systems, namely high effluent ammonia concentration, due to its high-volume exchange ratios. An ammonia oxidation rate of 32 mg N/Lh was achieved in the biofilm SBR, which produced nitrite as the final product. This nitrite stream was found to cause major inhibition on the anoxic P uptake and also to result in the accumulation of N(2)O. These problems were solved by feeding the nitrite-containing stream continuously to the granular reactor in the anoxic phase. With a nitrogen and phosphorus removal efficiency of 81% and 94%, respectively, the system produces an effluent that is suitable for land irrigation from a wastewater stream containing 270 mg N/L of total nitrogen and 40 mg P/L of total phosphorus.     

提高SBR工艺中脱氮除磷处理效果的措施

利用序批式反应器(SBR)试验装置对城市生活污水进行处理研究，讨论了影响SBR脱氮除磷的碳源、pH值、好氧曝气等因素，并对SBR工艺中脱氮除磷的相互影响进行了探讨，提出了可以同时脱氮除磷的一种SBR的运行方式。     

Development of biological filter as tertiary treatment for effective nitrogen removal: Biological filter for tertiary treatment

A biological filtration process applicable to tertiary treatment of sewage for effective nitrogen removal was developed. It consisted of a nitrification filter (Filter 1) and/or a polishing filter with anoxic and oxic parts (Filter 2). A pilot plant set at a municipal sewage treatment plant was operated for 525 d with feed of real sewage. The maximum apparent nitrification rate in Filter 1 in winter was 0.54 kg N/m3- filter-bed d. In Filter 2, the maximum denitrification capacity was 4 kg N/m3 filter-bed d) in winter. SS was stably removed and high transparency water was obtained. The target water quality (SS, BOD, and T-N5 mg/L) was accomplished in winter with the LV of 202 m/d in Filter 2, which corresponds to 0.24 h of HRT. These results proved that this process is compact, stable, convenient to install, and cost effective to build and operate as tertiary treatment to remove nitrogen effectively.