Physico-chemical and biological treatment of MSW landfill leachate

This paper analyses the evolution of the physico-chemical characteristics of the leachate from the Central Landfill of Asturias (Spain), which has been operating since 1986, as well as different treatment options. The organic pollutant load of the leachate, expressed as chemical oxygen demand (COD), reached maximum values during the first year of operation of the landfill (around 80,000 mg/L), gradually decreasing over subsequent years to less than 5000 mg/L. The concentration of ammonium, however, has not decreased, presenting values of up to 2000 mg/L. When feasible, recirculation can greatly decrease the organic matter content of the leachate to values of 1500–1600 mg COD/L. Applying anaerobic treatment to leachates with a COD between 11,000 and 16,000 mg/L, removal efficiencies of 80–88% were obtained for organic loading rates of 7 kg COD/m³ d. For leachates with lower COD (4000–6000 mg/L), the efficiency decreased to around 60% for organic loading rates of 1 kg COD/m³ d.Applying coagulation–flocculation with iron trichloride or with aluminium polychloride, it was possible to reduce the non-biodegradable organic matter by 73–62% when treating old landfill leachate (COD: 4800 mg/L, BOD₅: 670 mg/L), also reducing turbidity and colour by more than 97%. It is likewise possible to reduce the non-biodegradable organic matter that remains after biological treatment by adsorption with activated carbon, although adsorption capacities are usually low (from 15 to 150 mg COD/g adsorbent). As regards ammonium nitrogen, this can be reduced to final effluent values of 5 mg/L by means of nitrification/denitrification and to values of 126 mg/L by stripping at pH 12 and 48 h of stirring.     

Autotrophic Biological Denitrification for Complete Removal of Nitrogen from Septic System Wastewater

The overall objective of this research was to develop a reliable, robust, and maintenance-free passive system for biological denitrification in on-site wastewater treatment systems. The process relies on sulfur oxidizing denitrifying bacteria in upflow packed bioreactors. Since this process consumes alkalinity, it is necessary to add a solid-phase buffer that can scavenge the H⁺ as it is generated by the biologically-mediated reaction and arrest the drop in the pH value. This study investigated the use of limestone, marble chips and crushed oyster shell as solid-phase buffers that provide alkalinity. Two bench-scale upflow column reactors and two field-scale bioreactors were constructed and packed with sulfur pellets and an alkalinity source. The pilot scale bioreactors (∼200 L each) were installed at the Massachusetts Alternative Septic System Test Center (MASSTC) in Sandwich, MA. The pilot-scale bioreactors performed better when oyster shell was used as the solid-phase buffer vis-à-vis marble chips. In both (pilot-scale and laboratory-scale) systems, denitrification rates were high with the effluent NO₃ ⁻ —N concentration consistently below 8 mg/L.     

Anaerobic treatment of effluents from an industrial polymers synthesis plant

The feasibility of the anaerobic treatment of an industrial polymer synthesis plant effluent was evaluated. The composition of the wastewater includes acrylates, styrene, detergents, a minor amount of silicates and a significant amount of ferric chloride. The average chemical oxygen demand (COD) corresponding is about 2000 mg/l. The anaerobic biodegradability of the effluent is shown and the toxicity effect on the populations of anaerobic bacteria is evaluated. The results of the anaerobic biodegradation assays show that 62% of the wastewater compounds, measured as COD, could be consumed. An upflow anaerobic sludge blanket (UASB) reactor was used in the evaluation, it has a diameter–height ratio of 1:7, and 4-liter volume. The inoculum was obtained from a UASB pilot plant that treats brewery wastewaters. At the beginning of the operation, the biomass showed an anaerobic activity of 0.58 gCOD/(gVSS×d), it decreased only 2.5% in the subsequent 4 months. After 35 days of continuous operation, the reactor was operated at different steady states for 140 days. The COD was maintained at 2200 mg/l in the feed. The results were: organic loading rate (OLR): 4.3 kg COD/(m³×d), hydraulic retention time: 12 h, superficial velocity: 1 m/h, average biogas productivity: 290 L CH₄/kg COD fed, biogas composition: 70–75% methane and a COD removal percentage >75%. ©     

分子筛催化剂生产废水的生物处理

采用氨化—硝化—反硝化三段联合生物工艺处理分子筛催化剂生产过程中产生的含有机胺废水。实验结果表明：在氨化过程中,当进水COD稳定为1 200~1 600 mg/L时,出水COD低于300 mg/L,COD去除率稳定在80%左右,当进水ρ（有机氮）为100~160 mg/L时,出水ρ（有机氮）均低于30 mg/L,有机氮去除率大于80%,在整个氨化过程中,出水ρ（氨氮）较进水ρ（氨氮）提高了35~200 mg/L;硝化过程中,当进水ρ（氨氮）小于等于300 mg/L时,出水ρ（氨氮）最终稳定在15 mg/L以内,氨氮去除率大于90%;在反硝化过程中,亚硝酸盐氮去除率基本稳定在98%以上,最终出水COD低于80 mg/L,出水ρ（总氮）低于25 mg/L。     

Combined processes of two-stage Fenton-biological anaerobic filter–biological aerated filter for advanced treatment of landfill leachate

There are numerous non-biodegradable organic materials in the mature landfill leachate. To meet the new discharge standard of China, additional advanced treatment is needed for the effluent from the biological treatment processes of leachate. In this study, a combined process including two stages of “Fenton-biological anaerobic filter (BANF)–biological aerated filter (BAF)” was evaluated to address the advanced treatment need. The Fenton oxidation was applied to reduce chemical oxygen demand (COD) and enhance biodegradability of refractory organics, and the BANF–BAF process was then applied to remove the total nitrogen (TN). The treatment achieved effluent concentrations of COD < 70 mg/L, TN < 40 mg/L and NH₃–N < 10 mg/L. The removal efficiency of COD and TN were 96.1% and 95.9%, respectively. The effluent quality met the new discharge standard for Pollution Control on the Landfill Site of Municipal Solid of PR China (GB16889-2008). The operation cost of these processes was about 36.1 CHY/t (5.70 USD/t).     

Response surface analysis of effects of hydraulic retention time and influent feed concentration on performance of an UASFF bioreactor

The interactive effects of hydraulic retention time (HRT) and influent chemical oxygen demand (COD_in) on the performance of an up-flow anaerobic sludge fixed film (UASFF) bioreactor treating palm oil mill effluent (POME) was studied. Anaerobic digestion of POME was modeled and analyzed with two variables i.e. HRT and COD_in. Experiments were conducted based on a general factorial design and analyzed using response surface methodology (RSM). The region of exploration for digestion of POME was taken as the area enclosed by HRT (1–6 days) and COD_in (5260–34,725 mg/l) boundaries. Eight dependent parameters were either directly measured or calculated as response. Increase in the variables resulted in decrease in COD removal efficiency, solid retention time (SRT) and sludge retention factor (SRF) and increase of COD removal rate, volatile fatty acid to alkalinity ratio (VFA/Alk), CO₂ percentage in biogas and methane production rate. The value of the maximum specific microbial growth rate (μ_m) determined through the equation that correlated organic loading rate (OLR) and μ (calculated by quadratic model for SRF) was found to be 0.153 d^?1. This value was close to that obtained using Chen and Hashimoto kinetic equation (0.207 d^?1) in a previous study. The present study provides valuable information about interrelations of quality and process parameters in POME digestion using a UASFF bioreactor.     

厌氧／好氧生物脱氮－絮凝法处理焦化废水

采用厌氧／好氧生物脱氨－絮凝法处理焦化废水，出水中ＮＨ＿３－Ｎ＜１５ｍｇ／Ｌ，ＣＯＤ为９６－１５８ｍｇ／Ｌ。利用甲醇残液及其他有机废水作为外加碳源，可以达到以废治废的目的。     

基于固态碳源的自养-异养耦合生物脱氮工艺研究

采用基于固态碳源的厌氧氨氧化与反硝化耦合脱氮工艺处理高氮低碳的金属热处理废水。通过接种城市生活污水处理厂剩余污泥和厌氧氨氧化絮状污泥,研究了以固态碳源（3-羟基丁酸脂和3-羟基戊酸脂共聚物,PHBV）和沸石为组合填料的分区式耦合反应器的启动和运行特性。经过76 d的运行,耦合反应器的总氮去除速率达1.05 kg/（m³·d）,且具有良好的出水COD稳定性。废水经过反应器沸石区后,氨氮去除率达97%,亚硝态氮去除率达81%,而硝态氮去除率几乎为零;经过PHBV区后,硝态氮去除率达76%,亚硝态氮去除率达99%,氨氮去除率达97%。沸石区主要进行厌氧氨氧化反应,PHBV区主要进行反硝化反应,功能分区明确,耦合效果较好。     

Non-biodegradable landfill leachate treatment by combined process of agitation,coagulation, SBR and filtration

This study describes the complete treatment of non-biodegradable landfill leachate by combined treatment processes. The processes consist of agitation as a novel stripping method used to overcome the ammonia toxicity regarding aerobic microorganisms. The NH₃-N removal ratio was 93.9% obtained at pH 11.5 and a gradient velocity (G) 150 s^?1 within a five-hour agitation time. By poly ferric sulphate (PFS) coagulation followed the agitation process; chemical oxygen demand (COD) and biological oxygen demand (BOD₅) were removed at 70.6% and 49.4%, respectively at an optimum dose of 1200 mg L^?1 at pH 5.0. The biodegradable ratio BOD₅/COD was improved from 0.18 to 0.31 during pretreatment step by agitation and PFS coagulation. Thereafter, the effluent was diluted with sewage at a different ratio before it was subjected to sequencing batch reactor (SBR) treatment. Up to 93.3% BOD₅, 95.5% COD and 98.1% NH₃-N removal were achieved by SBR operated under anoxic–aerobic–anoxic conditions. The filtration process was carried out using sand and carbon as a dual filter media as polishing process. The final effluent concentration of COD, BOD₅, suspended solid (SS), NH₃-N and total organic carbon (TOC) were 72.4 mg L^?1, 22.8 mg L^?1, 24.2 mg L^?1, 18.4 mg L^?1 and 50.8 mg L^?1 respectively, which met the discharge standard. The results indicated that a combined process of agitation-coagulation-SBR and filtration effectively eliminated pollutant loading from landfill leachate.     

悬浮滤料在上向流反硝化滤池中试装置中的应用

以聚苯乙烯泡沫滤珠作为上向流反硝化滤池的滤料,在中试装置中考察了此种悬浮滤料的脱氮效果及其过滤功能.试验结果表明:在进水流量为13.5 m3/h的情况下,随着碳氮质量比(碳氮比)的升高,NO3--N去除率逐渐提高,出水COD也逐渐提高,适宜的碳氮比为5,此条件下出水COD小于50 mg/L;水力停留时间(HRT)越长,...     

高氨氮化工废水MBBR—AMBBR—MBBR组合工艺处理

采用移动床生物膜反应器（MBBR）—厌氧移动床生物膜反应器（AMBBR）—MBBR组合工艺处理高氨氮化工废水。反应器采用几何构型优化、比表面积大的新型YD-25生物载体和DNF-203硝化细菌,实现了同步硝化和反硝化,强化了脱氮能力。采用投加菌种和排泥的方式,经27 d的驯化培养即完成了反应器的挂膜启动。试验结果表明：最佳操作条件为HRT 8 d、MBBR中DO 3 mg/L、进水pH 8.0;在进水COD 2 840~7 437 mg/L、ρ（氨氮）92~179 mg/L、TN 148~258 mg/L、pH 6~8的条件下,出水指标均值为COD 352 mg/L、ρ（氨氮）21.2 mg/L、TN 36 mg/L、pH 7.4,满足排放要求。     

Enhanced anaerobic treatment of CSTR-digested effluent from chicken manure: The effect of ammonia inhibition

The effect of ammonia inhibition was evaluated during the enhanced anaerobic treatment of digested effluent from a 700 m³ chicken-manure continuous stirred tank reactor (CSTR). A 12.3 L internal circulation (IC) reactor inoculated with an anaerobic granular sludge and operated at 35 ± 1 °C was employed for the investigation. With a corresponding organic loading rate of 1.5-3.5 kg-COD/m³ d over a hydraulic retention time of 1.5 d, a maximum volumetric biogas production rate of 1.2 m³/m³ d and TCOD (total COD) removal efficiency ranging from 70% to 80% was achieved. However, the continual increase in the influent TAN content led to ammonia inhibition in the methanogenesis system. The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was presented to be the key controlling factor for the anaerobic treatment of semi-digested chicken manure, and further validation through shock loading and ammonia inhibition experiments was conducted. The threshold value of the SCOD/TAN ratio was determined to be 2.4 (corresponding to a TAN of 1250 mg/L) at an influent pH of 8.5-9.     

Cr（Ⅵ）对活性污泥系统反硝化过程的影响

采用反硝化反应器,研究了Cr（Ⅵ）对活性污泥系统反硝化过程的影响。在进水Cr（Ⅵ）投加量2.5 mg/L条件下,活性污泥反硝化过程中COD和硝酸盐氮的去除率受到的影响较小,而在10.0 mg/L条件下受到的影响较大,COD和硝酸盐氮的去除率分别从最初的97.1%和99.0%降至70.6%和24.7%。在停止投加Cr（Ⅵ）后的恢复期内,反硝化系统可以逐渐恢复对COD和硝酸盐氮的去除,亚硝酸盐氮仍会有积累,但随着时间的延长可恢复至初始状态。硝酸盐氮还原为亚硝酸盐氮的过程比亚硝酸盐氮的还原过程更易受到Cr（Ⅵ）的影响。     

Organic and nitrogen removal from landfill leachate in aerobic granular sludge sequencing batch reactors

Granule sequencing batch reactors (GSBR) were established for landfill leachate treatment, and the COD removal was analyzed kinetically using a modified model. Results showed that COD removal rate decreased as influent ammonium concentration increasing. Characteristics of nitrogen removal at different influent ammonium levels were also studied. When the ammonium concentration in the landfill leachate was 366 mg L⁻¹, the dominant nitrogen removal process in the GSBR was simultaneous nitrification and denitrification (SND). Under the ammonium concentration of 788 mg L⁻¹, nitrite accumulation occurred and the accumulated nitrite was reduced to nitrogen gas by the shortcut denitrification process. When the influent ammonium increased to a higher level of 1105 mg L⁻¹, accumulation of nitrite and nitrate lasted in the whole cycle, and the removal efficiencies of total nitrogen and ammonium decreased to only 35.0% and 39.3%, respectively. Results also showed that DO was a useful process controlling parameter for the organics and nitrogen removal at low ammonium input.     

A Novel Biodegradable Fluorine-Containing Copolymer Surfactant

A novel fluorine-containing copolymer surfactant was synthesized via free radical copolymerization from maleic anhydride and rapeseed oil firstly, and then followed by an esterification reaction with dodecafluoro heptanol. The reaction progresses were monitored on-line by FTIR and the copolymerization was characterized by molecular weight (GPC) analysis. Simultaneously, the surface tension and critical micelle concentration (CMC) together with the biodegradability of the fluorine-containing copolymer surfactant were investigated in detail. The results indicate that this fluorine-containing surfactant with Mw of 66000 g/ mol and Mn of 38800 g/mol shows a strong surface tension lowering ability, the CMC is 0.1 g/L, the surface tension value at the CMC (γ_CMC) is 22.5 mN m⁻¹ and less than the corresponding copolymeric hydrocarbon surfactant; the evaluation of biodegradability indicates that the biological respiration curve of the fluorine-containing copolymer surfactant with concentration of 1000 mg/L is above the endogenous respiration curve; the BOD₅/COD value is higher than 0.45; the COD and TOC removal ratios after 5 days of biodegradation reach 91.0 and 89.4%, respectively, showing good biodegradability and environmental-friendly feature.     

Landfill leachate treatment by electrochemical oxidation

This study investigated the electrochemical oxidation of stabilized leachate from Pulau Burung semi-aerobic sanitary landfill by conducting laboratory experiments with sodium sulfate Na₂SO₄ (as electrolyte) and graphite carbon electrodes. The control parameters were influent COD, current density and reaction time, while the responses were BOD removal, COD removal, BOD:COD ratio, color and pH. Na₂SO₄ concentration was 1 g/L. Experiments were conducted based on a three-level factorial design and response surface methodology (RSM) was used to analyze the results. The optimum conditions were obtained as 1414 mg/L influent COD concentration, 79.9 mA/cm² current density and 4 h reaction time. This resulted in 70% BOD removal, 68% COD removal, 84% color removal, 0.04 BOD/COD ratio and 9.1 pH. Electrochemical treatment using graphite carbon electrode was found to be effective in BOD, COD and color removal but was not effective in increasing the BOD/COD ratio or enhancing biodegradability of the leachate. The color intensity of the treated samples increased at low influent COD and high current density due to corrosion of electrode material.     

Membrane bioreactor technology: A novel approach to the treatment of compost leachate

Compost leachate forms during the composting process of organic material. It is rich in oxidizable organics, ammonia and metals, which pose a risk to the environment if released without proper treatment. An innovative method based on the membrane bioreactor (MBR) technology was developed to treat compost leachate over 39 days. Water quality parameters, such as pH, dissolved oxygen, ammonia, nitrate, nitrite and chemical oxygen demand (COD) were measured daily. Concentrations of caffeine and metals were measured over the course of the experiment using gas chromatography – mass spectrometry (GC/MS) and inductively coupled plasma – mass spectrometry (ICP–MS) respectively. A decrease of more than 99% was achieved for a COD of 116 g/L in the initial leachate. Ammonia was decreased from 2720 mg/L to 0.046 mg/L, while the nitrate concentration in the effluent rose to 710 mg/L. The bacteria in the MBR system adjusted to the presence of the leachate, and increased 4 orders of magnitude. Heavy metals were removed by at least 82.7% except copper. These successful results demonstrated the membrane bioreactor technology is feasible, efficient method for the treatment of compost leachate.     

制药废水硝化-反硝化除氮研究

含高浓度氮的制药废水经好氧生化处理后,虽然出水的ＣＯＤ,ＢＯＤ５均可达到行业排放标准,但ＴＮ仍高达约１７０ｍｇ／Ｌ。本研究在曝气池中设置填料,利用生物膜外层好氧,内层缺氧厌氧的条件,使硝化－反硝化脱氮在同一构筑物内进行,ＮＨ３－Ｎ和ＴＮ去除率分别可达约９０％和７０％。在本试验条件范围内,温度越高,负荷越低,硝化和反硝化作用越完全,ＮＨ３－Ｎ和ＴＮ去除率越高。     

“二级厌氧-微氧-好氧”组合工艺处理模拟碳纤维生产废水

对模拟碳纤维生产废水进行“厌氧-好氧”静态小试,根据COD的去除效果确定该碳纤维废水的可生化性。采用“二级厌氧-微氧-好氧”组合工艺进行动态中试,考察废水的处理效果及系统的抗冲击性能。试验结果表明：该工艺对碳纤维生产废水的处理效果较好;系统具有厌氧池出水pH增大的特点,且抗冲击能力较强;在厌氧池水温为28~38 ℃、好氧池水温不低于15 ℃、废水流量为100 L/h、进水COD为660 mg/L、进水ρ（氨氮）为4.9 mg/L的条件下,出水COD稳定在50 mg/L以下,ρ（氨氮）稳定在5 mg/L以下,能够满足GB 8978-1996《污水综合排放标准》的要求。     

Fenton氧化-生物接触氧化工艺处理甲醛和乌洛托品废水

采用Fenton氧化一生物接触氧化工艺处理含甲醛和乌洛托品的模拟废水（简称废水），在H2O2（体积分数30％）加入量2．5g／L、H2O2与Fe^2＋质量浓度比3．75、反应时间3h、不调节废水初始pH的Fenton氧化预处理最佳操作条件下，废水COD从1000mg／L左右降至300mg／L，COD去除率达72％。原废水完全无法直接进行生化处理，经Fenton氧化预处理后其BOD，／COD约为0．5，易于生化处理。Fenton氧化一生物接触氧化工艺处理废水，生物接触氧化停留时间为12h时，废水COD去除率高达94％，处理后出水COD小于70mg／L，处理效果很好。