固定化的栅藻深度脱氮和除磷能力

将栅藻包埋固定在筛网上,经饥饿处理,在平行板式生物反应器中对人工污水进行深度净化后,测定藻细胞生长期和饥饿时间对NH4^＋-N和PO4^3-P去除效率影响以及净化前后藻细胞生理变化的结果表明,生长静止初期藻细胞的氮和磷去除率高于对数期的,细胞饥饿48h的氮和磷去除率大于饥饿24和12h,第2个循环中处理4h的氨氮和磷的去除率可分别达到90％和70％以上。     

固定化微绿球藻去除NH4+-N、PO43——P效果的研究

为了探究固定化微绿球藻（Nannochloropsis oculata）去除污水中NH4+-N、PO43--P的效果,采用海藻酸钠固定化包埋技术进行实验。开展了固定化藻球大小、藻细胞包埋密度、藻球投放质量及充气培养条件对NH4+-N、PO43--P去除效果的单因子试验研究。结果表明,固定化藻球大小、藻细胞包埋密度、藻球投放质量和充气培养条件对NH4+-N、PO43--P的去除效果影响显著（P0.05）。藻球直径3.5 mm时生长速率（K）值最大（0.3320.002）,同时NH4+-N、PO43--P去除率效果最佳,分别为（75.083.83）%和（80.803.81）%;藻细胞包埋密度100104 cells/ball时K值最大（0.3300.033）,而NH4+-N、PO43--P去除率则以藻细胞包埋密度300104 cells/ball组为佳,分别达（87.200.43）%和（82.581.72）%,但考虑单位藻细胞去除率,包埋密度以100104 cells/ball为宜;随着藻球用量的增加K值下降,10 g/L组K值最大（0.3010.02）、50 g/L组K值最小（0.1930.01）,投放量30和50 g/L时NH4+-N去除率较高分别为（84.120.78）%和（84.630.45）%,30 g/L组PO43--P去除率最高达（77.131.43）%。综合考虑,藻球投放量选用30 g/L为宜;充气条件培养K值、NH4+-N和PO43--P去除率显著（P0.05）高于不充气,K值分别为（0.3060.006）和（0.1770.010）;NH4+-N去除率分别为（85.930.45）%和（49.320.45）%;PO43--P去除率分别为（66.665.00）%和（46.292.12）%。研究优化了微绿球藻固定化条件:固定化微绿球藻应进行充气培养,藻球规格3.5 mm、藻细胞包埋密度100104 cells/ball、藻球投放量30 g/L。     

Intermittent cyclic process for enhanced biological nutrient removal treating combined chemical laboratory wastewater

The aim of this work was to assess the efficacy for simultaneous enhanced removal of nitrogen and phosphorus including organics treating combined wastewater generated from a chemical laboratory using a bench-scale Intermittent Cyclic Process Bio-reactor (ICPBR). The performance efficacy indicated that the ICPBR system with solid retention time of 15 days achieved optimum efficiency with an overall removal of ammonia nitrogen (NH4-N), phosphorus (PO4-P), and chemical oxygen demand (COD) in the range, 83-92%, 74-93%, and 90-96%, respectively.     

Removal of ammonia as struvite from anaerobic digester effluents and recycling of magnesium and phosphate

A second order kinetic model was developed to predict the rate and extent of NH(4)(+) removal as struvite from anaerobic digester effluents. Alternative to this, NH(4)(+) can be recovered from struvite and the remaining Mg(2+) and PO(4)(3-) can be recycled back to the wastewater to fix more NH(4)(+). The NH(4)(+) solution was retained and the remaining Mg(2+) and PO(4)(3-) were returned back to be mixed with wastewater. In a five-step process, NH(4)(+) recovery was initially 92% and progressively decreased to 77% in the fifth stage, due to loss of Mg(2+) and PO(4)(3-) at each step in the supernatant. Finally, economic analysis of recycling nutrients was performed and compared to the one step process. The cost of NH(4)(+) recovery was calculated as $0.36/kgNH(4)-N which is lower than $7.7/kgNH(4)-N the cost of one step process without considering the market value of struvite obtained in one step process.     

Effect of carbon source on biological nutrient removal in a sequencing batch reactor

Sequencing batch operation was used for nutrient (COD, NH4-N, NO3-N, PO4-P) removal from synthetic wastewater by using different carbon sources. Operation consisted of anaerobic, anoxic, oxic, anoxic and oxic (An/Ax/Ox/Ax/Ox) phases with durations of 2/1/4.5/1.5/1.5 h. Glucose, acetate and a mixture of glucose/acetate were used as carbon source to yield a COD/N/P ratio of 100/5/1.5 in the feed. Sludge age was kept constant at 10 days. COD, NH4-N, NO3-N and PO4-P removal efficiencies were maximum at the levels of 96%, 87%, 81% and 90% respectively, when a mixture (50/50) of glucose and acetate was used.     

Simultaneous sludge reduction and nutrient removal (SSRNR) with interaction between Tubificidae and microorganisms: a full-scale study

A symbiotic ecosystem between Tubificidae and microorganisms was established at a full-scale wastewater treatment plant (WWTP). In this ecosystem Tubificidae were inoculated, and then adhered to the outer layers of carrier materials in an oxidation tank. During the long-term treatment of sewage volumes of 20,000 m(3)d(-1), the excess sludge production rate was reduced from 0.21 to 0.051 kg m(-3) and sludge settleability was significantly improved. When the influent concentrations of COD, NH(4)(+)-N, PO(4)(-)-P, and SS were in the ranges of 130.0-459.0 mg L(-1), 14.2-27.5 mg L(-1), 1.6-7.0 mg L(-1), and 60.0-466.0 mg L(-1), respectively, the COD and SS removal efficiency was increased by 8.7% and 13.6% within the symbiotic system compared to the control without Tubificidae. In addition, NH(4)(+)-N and phosphorus removal efficiency can also be improved. The results showed that both sludge reduction and nutrient removal were enhanced simultaneously significantly within the system utilizing the symbiotic interactions of Tubificidae and microorganisms.     

Effects of ammonia and phosphate limitation on the activated sludge treatment of calcium-containing chemical waste

Laboratory-scale biotreaters were used to study the effects of NH(3)-N and PO(4)-P nutrients on the activated sludge treatment of a chemical waste containing soluble calcium (1300 mg/L). Units receiving high or low levels of NH(3)-N and PO(4)-P were similar in their ability to remove organic compounds from the waste. Adaptation of sludges to low PO(4)-P levels (<0.1 mg/L effluent) resulted in a marked accumulation of CaCO(3) in the biosolids, whereas those receiving high PO(4)-P (2-4 mg/L effluent) had little CaCO(3). Microscopic observations of CaCO(3) containing sludges showed substantial amounts of CaCO(3) crystals imbedded in the biomass. These flocs also appeared to be enriched with nonfilamentous bacterial species in contrast to flocs devoid of CaCO(3) which had a floc structure of filamentous and nonfilamentous organisms. Scanning electron micrographs of flocs grown under low NH(3)-N showed a microbial fibrillar network of exocellular material interconnecting cells in the floc matrix. The sludges adapted to low NH(3)-N also produced higher amounts of extractable polysaccharide. CaCO(3) containing biosolids were more dense, larger, and settled better (low SVI, high ISV) than flocs devoid of the precipitates. It is not known from our experiments whether PO(4)-P or some inorganic or organic polymer produced by the floc bacteria are involved in inhibiting CaCO(3) precipitation in the activated sludge treatment of calcium-containing wastes.     

Treatment of tomato processing wastewater by an upflow anaerobic sludge blanket-anoxic-aerobic system

The main objective of this study is to assess the achievability of stringent discharge criteria i.e. BOD(5)<15 mg/L, TSS<15 mg/L and NH(4)-N<1mg/L during the treatment of tomato processing wastewater with COD of 2800-15,500 mg/L, BOD(5) of 1750-7950 mg/L, TKN of 48-340 mg/L and NH(4)-N of 21-235 mg/L. Two treatment systems, a UASB-aerobic system and a UASB-anoxic-aerobic system were tested. Furthermore due to alkalinity deficiency, in the raw wastewater, the study explored varying UASB effluent recirculation flowrates to the UASB influent to reduce additional alkalinity requirements. The UASB-anoxic-aerobic system was effective in treating tomato canning wastewater at an overall HRT of 1.75 days while achieving 98.5% BOD(5), 95.6% COD, 84% TSS and 99.5% NH(4)-N removal producing effluent BOD(5), COD, TSS, NH(4)-N, TKN, NO(2)-N, NO(3)-N and PO(4)-P of 10, 70, 15, 0.5, 3, 0, 60 and 4 mg/L, respectively. The biogas yield was 0.43 m(3)/kg COD removed.     

Influence of nitrate and COD on phosphorus, nitrogen and dinitrotoluene (DNT) removals under batch anaerobic and anoxic conditions

In this study, the effects of COD to NO(3)-N ratio in the feed on PO(4)-P removal was investigated. Maximum PO(4)-P uptake was obtained in the anoxic reactor when the COD to NO(3)-N ratios were between 2 and 3.75. With the influent COD of 800-1500 mg COD/L a total of the maximum removable PO(4)-P was 56 mg PO(4)-P/L through 20 days of anaerobic/anoxic incubation, indicating 98% P removal in the anoxic reactor. Similarly, for the COD to NO(3)-N ratios varying between 2 and 3.75 maximum denitrification was observed. Through anoxic operation the poly-P bacteria are capable of removing NO(3)-N using VFA, COD as carbon source and NO(3)-N as the electron acceptor after methanogenesis has been completed. High NO(3)-N concentrations stopped significantly the P uptake. A total of 97-99% dinitrotoluene removal efficiencies in the reactors containing COD to NO(3)-N ratio of 2 and 3.75 after 20 days of incubation period. For maximum NO(3)-N and PO(4)-P removals optimal COD to NO(3)-N ratios, COD and NO(3)-N concentrations were 2-3.75, 2000-4000 mg COD/L and, 800-1500 mg NO(3)-N/L, respectively.     

Simultaneous removal of phosphorus and nitrogen in a sequencing batch biofilm reactor with transgenic bacteria expressing polyphosphate kinase

To improve phosphorus removal from wastewater, we constructed a high-phosphate-accumulating microorganism, KTPPK, using Pseudomonas putida KT2440 as a host. The expression plasmid was constructed by inserting and expressing polyphosphate kinase gene (ppk) from Microcystis aeruginosa NIES-843 into broad-host-range plasmid, pBBR1MCS-2. KTPPK was then added to a sequencing batch biofilm reactor (SBBFR) using lava as a biological carrier. The results showed that SBBFR with KTPPK not only efficiently removed COD, NH(3)-N, and NO(3)(-)-N but also had a high removal capacity for PO(4)(3-)-P, resulting in a low phosphorus concentration remaining in the outflow of the SBBFR. The biofilm increased by 30-53% on the lava in the SBBFR that contained KTPPK after 11 days when compared with the reactor that contained P. putida KT2440. Real-time quantitative polymerase chain reaction confirmed that the copy of ppk was maintained at about 3.5 × 10(10) copies per μL general DNA in the biofilm after 20 days. Thus, the transgenic bacteria KTPPK could maintain a high density and promote phosphorus removal in the SBBFR. In summary, this study indicates that the use of SBBFR with transgenic bacteria has the potential to remove phosphorus and nitrogen from wastewater.     

Correlating on-line monitoring parameters, pH, DO and ORP with nutrient removal in an intermittent cyclic process bioreactor system

The paper presents the study correlating the profile of on-line monitoring parameters and nutrient removal in an intermittent cyclic process bioreactor (ICPBR) system, thereby utilizing the parameters as operational tool. A laboratory scale ICPBR was employed to treat low C/N ratio domestic wastewater from a township. The study was conducted for correlating biological nutrient removal and on-line monitored parameters pH, dissolved oxygen (DO) and oxidation-reduction potential (ORP). The results revealed that pH, DO and ORP related with the dynamic behavior of nutrient concentration (NH4-N, NO3-N, and PO4-P) during treatment in an ICPBR system. The variation in pH and ORP of the reactor liquor correlate to conversion of ammonia (NH4-N) and nitrate (NO3-N) concentrations, respectively. As the bioconversion of ammonia nitrogen and phosphorus are related to the varying profile of the on-line monitored parameters, the profiles could possibly be used as onsite process control parameters.     

Enhanced denitrifying phosphorous removal in a novel anaerobic/aerobic/anoxic (AOA) process with the diversion of internal carbon source

A novel anaerobic/aerobic/anoxic (AOA) process is proposed to realize denitrifying phosphorous removal in this study, and the characteristic of the AOA process is transferring part of the anaerobic mixed liquor to the post-anoxic zone for providing the carbon source needed for denitrification. The AOA process was operated for 3 months, and the average removal efficiencies of NH4+-N, TN and PO4(3-)-P were 93.0±3.1%, 70.3±2.9% and 87.3±11.8%, respectively. A mass balance analysis indicated that 0.49±0.02 g VSS(-1) d(-1) of PO4(3-)-P and 0.23±0.04 g VSS(-1) d(-1) of NO3--N were simultaneously removed in the anoxic zone, and it is speculated that denitrifying phosphorous removal occurred in the AOA process. Furthermore, 0.24±0.06 g VSS(-1) d(-1) of TN was removed in the aerobic zone via simultaneous nitrification and denitrification (SND). The results demonstrate that the multi-zone structure of the AOA process favors the enhancement of denitrifying phosphorous removal and SND for municipal wastewater treatment.     

Uptake rates of nitrogen and phosphorus in the water by Eichhornia crassipes and Salvinia auriculata

The main goal of this research was to survey information about the physiology of Eichhornia crassipes and Salvinia auriculata and their capacity to remove nitrogen and phosphorus from the environment, after quantifying the concentrations of the nitrogen (NO3-N, NH4-N and total-N) and phosphorus (PO4-P and total-P) compounds in the water. The macrophytes were incubated in the laboratory in plastic vials of approximately 1.5 litters containing a previously prepared solution of NH4NO3, NH4Cl and KH2PO4. Eichhornia crassipes exhibited the highest rates of nutrient reduction and the concentrations of NO3-N, NH4-N and PO4-P in the water influenced the uptake rates of nitrogen and phosphorus of the E. crassipes and S. auriculata. This information can help to reach adequate management strategies for aquatic macrophytes in order to reduce the eutrophication process in Imboassica lagoon.     

Autotrophic denitrification and chemical phosphate removal of agro-industrial wastewater by filtration with granular medium

A novel granular medium consisting (1.5-5 mm in diameter) of inert perlite particles as nuclei and an effective surface layer containing sulfur, CaCO3 and Mg(OH)2 was developed for advanced treatment of agro-industrial wastewater. The performance of the medium was examined with a laboratory-scale down-flow fixed-bed column reactor using piggery wastewater, which had been treated by an upflow anaerobic sludge blanket reactor and a trickling filter. The removal efficiency of NOx- -N was more than 70% with a NOx- -N loading rate of less than approximately 0.3 kg Nm(-3) d(-1); the removal efficiency dropped due to the accumulation of nitrite when the loading rate exceeded that value. A significant drop of phosphate and Mg2+ concentrations occurred when the effluent pH exceeded 7.9. Ammonium was removed with an average removal efficiency of 12.4%. These results indicated that the crystalline reaction of PO4(3-), Mg2+ and NH4+ (MAP reaction) under alkaline conditions contributed to the removal of phosphate. This medium could be useful for the simultaneous reduction of nitrogenous and phosphorus compounds in biologically treated agro-industrial wastewater.     

para-Chlorophenol inhibition on COD, nitrogen and phosphate removal from synthetic wastewater in a sequencing batch reactor

COD, nitrogen, phosphate and para-chlorophenol (4-chlorophenol, 4-CP) removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (SBR) at different sludge ages and initial para-chlorophenol (4-CP) concentrations. The nutrient removal process consisted of anaerobic, oxic, anoxic and oxic phases with hydraulic residence times (HRT) of 1/3/1/1 h and a settling phase of 0.75 h. A Box-Wilson statistical experiment design was used considering the sludge age (5-25 days) and 4-CP concentration (0-400 mg l(-1)) as independent variables. Variations of percent COD, NH4-N, PO4-P and 4-CP removals with sludge age and initial 4-CP concentration were investigated. Percent nutrient removals increased with increasing sludge age and decreasing 4-CP concentrations. Low nutrient removals were obtained at high initial 4-CP concentrations especially at low sludge ages. However, high sludge ages partially overcome the adverse effects of 4-CP and resulted in high nutrient removals. COD, NH4-N, PO4-P and 4-CP removals were 76%, 72%, 26% and 34% at a sludge age of 25 days and initial 4-CP concentration of 200 mg l(-1). Sludge volume index (SVI) also decreased with increasing sludge age and decreasing 4-CP concentrations. An SVI value of 104 ml g(-1) was obtained at a sludge age of 25 days and initial 4-CP of 200 mg l(-1).     

Struvite precipitation in anaerobic swine lagoon liquid: effect of pH and Mg:P ratio and determination of rate constant

Because of increased concern about surface water eutrophication from nutrient-enriched agricultural runoff, many swine producers are encouraged to decrease application rates of waste-based P. Precipitation and subsequent removal of magnesium ammonium phosphate (MgNH(4)PO(4) x 6H(2)O), commonly known as struvite, is a promising mechanism for N and P removal from anaerobic swine lagoon effluent. The objectives of this research were to (i) quantify the effects of adjusting pH and Mg:P ratio on struvite precipitation and (ii) determine the rate constant pH effect for struvite precipitation in anaerobic swine lagoon liquid. Concentrations of PO(4)-P in liquid from two anaerobic swine lagoons were determined after 24 h of equilibration for a pH range of 7.5-9.5 and Mg:P ratios between 1:1 and 1.6:1. Struvite formation reduced the PO(4)-P concentration in the effluents to as low as 2 mgl(-1). Minimum concentrations of PO(4)-P occurred between pH 8.9 and 9.25 at all Mg:P ratios. Struvite precipitation decreased PO(4)-P concentrations by 85% within 20 min at pH 9.0 for an initial Mg:P ratio of 1.2:1. The rate of PO(4)-P decrease was described by a first-order kinetic model, with rate constants of 3.7, 7.9, and 12.3 h(-1) at pH 8.4, 8.7 and 9.0 respectively. Our results indicate that induced struvite formation is a technically feasible method to remove N and P from swine lagoon liquid and it may allow swine producers to recover nutrients for off-farm sale.     

Water treatment of land-based fish farm effluents by outdoor culture of marine diatoms

The feasibility of using fish farm effluents was evaluated as a source of inorganic nutrients for mass production of marine diatoms. Batch cultures were conducted from May to July 1995 in 16-L outdoor rectangular tanks, homogenized by gentle aeration (0.2 L _air L^–1 h^–1). The effluents from the two fish farms studied were both characterized by high concentrations of inorganic materials (NH₄-N, PO₄-;P, Si(OH)₄-Si) and were shown to support production of marine diatoms. Moreover, periodic measurements of inorganic matter levels in the cultures showed that clearance was efficacious (90% in 3–5 days). Water purification efficiency and culture productivity were further increased through appropriate nutrient balancing. When effluents were limited in silicate, addition of Na₂SiO₃ induced a significant increase in both diatom biomass and nutrient removal efficiency. In this case, up to 720 000 cell mL^–1 were produced dominated bySkeletonema costatum. By contrast, in effluents loaded with silicate, adjustment of the N:P:Si ratio by NH₄-N and PO₄-P supplementation then gave increased biomass production. In this case, the maximum cell density found was 450 000 cell mL^–1, dominated byChaetoceros spp.Author for correspondence     

Evaluation of a novel sponge-submerged membrane bioreactor (SSMBR) for sustainable water reclamation

A novel sponge-submerged membrane bioreactor (SSMBR) to treat a high strength wastewater for water reclamation was developed in this study. The performance of this system was evaluated using two kinds of polyester-urethane sponges (coarse sponge with higher density S28-30/45R and fine sponge with lower density S16-18/80R) with sponge volume fraction of 10% and bioreactor MLSS of 10 g/L. The results indicated the addition of sponge in SMBR could increase sustainable flux (2 times for S28-30/45R and 1.4 times for S16-18/80R) and lower TMP development, thus significantly reduce membrane fouling. S28-30/45R gave rise in attached growth biomass and the removal efficiencies of DOC, COD and PO4-P whilst S16-18/80R had better performance in removing NH4-N. Although the SSMBR performed well for most of the trials, the superior recycled water quality was achieved when adding S28-30/45R and S16-18/80R together in SMBR with the ratio of 2:1 and without any pH adjustment during the operation.     

PS1沼泽红假单胞菌对集约化对虾养殖废水的净化作用

应用光合细菌PS1——沼泽红假单胞菌（Rhodopseudomonas palustris）净化集约化对虾养殖废水,探讨不同温度、不同菌浓度下PS1对养殖废水的净化效果。研究结果表明：PS1可有效降低对虾养殖废水中的COD、NH4^＋-N、NO3^-N、PO4^3--P,但对NO2^--N无降解效果,反而使之持续升高;PS1对养殖废水96h的降解率受温度和添加菌浓度的影响显著（P〈0．05）。当温度为26℃时,PS1对废水的降解活性较好;不同菌浓度组间的净化效果差异明显（P〈0．05）,综合净化效果,以12．5×10^5 CFU／ml的菌浓度为宜。     

Simultaneous ammonium-nitrogen and copper removal, and copper recovery using nitrifying biofilm from the ultra-compact biofilm reactor

Simultaneous ammonium-nitrogen (NH(4)(+)-N) and copper removal, and copper recovery in synthetic wastewater using nitrifying biofilm from an ultra-compact biofilm reactor (UCBR) was demonstrated in batch studies, which consisted of three phases: Phase 1 for NH(4)(+)-N and copper removals, Phase 2 for copper recovery, and Phase 3 for NH(4)(+)-N removal. The results showed that more than 96.3% of copper was removed within 60min, while 60.1% of the adsorbed copper was recovered through rinsing the biofilms with 0.1mM of ethylenediaminetetraacetic acid (EDTA). The nitrifying biofilm was able to adsorb 0.245mg of copper/g of biofilms. After recovery treatment, 29.4% of copper remained bound within the nitrifying biofilms. No significant inhibitory effects towards NH(4)(+)-N removal in the presence of 0.92mg copper/L was noted in Phase 1 compared with the control test. However, lower initial pH condition in the recovery process and the accumulation of copper on the biofilm led to 50% inhibition on NH(4)(+)-N removal efficiency in the subsequent phase.