Temperature dependency of granule characteristics and kinetic behavior in UASB reactors

When an inhibitory substrate, phenol, was treated under mesophilic conditions (25, 30, 35, and 40 °C), the upflow anaerobic sludge bed (UASB) reactors at 30 °C resulted in the greatest amount of biomass and the largest granule size, while the UASB reactors at 25 °C resulted in the smallest granule size and the greatest amount of wash‐out of sludge. The granule size tended to be negatively correlated with the amount of wash‐out of sludge. With an increase in temperature, the kinetic constant k for anaerobic phenol degradation increased and the half saturation constant (K_s) decreased. The mass fraction of methanogens (f) increased with increasing operational temperature in the UASB reactors and the activation energy (E_a) for acetate methanogenesis was larger than that for phenol acidogenesis in the batch reactors, indicating that the operational temperature imposes a more influential effect on methanogens than on acidogens. From the results of the activity of acidogens and methanogens (expressed in specific COD utilization rate), the rate‐limiting step is phenol acidogenesis. Copyright © 2004 Society of Chemical Industry     

An Integrated Approach to Lysis-Cryptic Growth (Sludge Ozonation) and Sequencing Batch Reactor Coupled to an Anaerobic Side-Stream Reactor (SBR-ASSR): Performance and Characteristics

ABSTRACT

Anaerobic side-stream reactors (ASSR) have been suggested to reduce waste activated sludge volumes benefiting from relatively low capital/operation costs and design simplicity. In this study, an evaluation of the feasibility of combining the ASSR system with the lysis-cryptic growth (ozonation) process was made so that a part of the sludge which passed through the ASSR anaerobic tank would be then treated by ozonation before returned to the aeration tank. The main independent factor was the ozonation flowrate (OFR), which is defined as the percent of return sludge which passed through the both the anaerobic tank and the ozonation unit. Three systems were studied, an ASSR control without ozonation (OFR-0), a combined ASSR with ozonation designated as OFR-2.5 (anaerobic interchange rate [AIR] of 10% per day and 25% of the exchanged sludge being ozonated [ozone interchange rate or OIR]), and OFR-3.1 (AIR = 12.5%, OIR = 25%). The results revealed that the insertion of an ozonation step led to an enhanced total microbial activity, eukaryotic population, and nitrogen removal. The linear relationship between the observed yield and the specific oxygen uptake rate indicated that microbial predation was the major relevant mechanism for the enhanced sludge reduction. The results of measurements of particle size distribution, and sludge dewaterability rates suggest that additional studies are needed to better understand and optimize this system.     

Anaerobic treatment of acidified and non‐acidified substrata in UASB reactors

The selection of a suitable sludge which will be the inoculum of the reactor is the first step in the start‐up procedure of an anaerobic reactor. The sludge selected (inoculum) for this study was obtained from a UASB (Up‐flow Anaerobic Sludge Bed) reactor used for the treatment of alcohol industry wastewaters. The industrial sludge was used in this work as the inoculum of two laboratory‐scale UASB anaerobic reactors, which were fed with different substrata. The feed for the first reactor was acidified substratum (volatile fatty acid) and the second reactor was fed with non‐acidified substratum (glucose). The purpose of this work was to study the effect of both substrata in regular operation and to analyse the flotation problem which arises when the reactor is fed with a non‐acidified substratum. Finally, the characteristics of the adapted sludge were studied and they were compared with the initial inolucum (sludge). The following observations were noted in relation to the evolution of the sludge during operation: density, TSS content and C, H and N contents remained similar, but the particle size and VSS/TSS increased. The settling volume index decreased and methanogenic and acidogenic activities increased during operation in both reactors. The reactor fed with volatile fatty acids was able to recover from unstable periods faster than the reactor fed with a non‐acidified substratum. The use of an acidified substratum avoided flotation, stabilised the system and reduced the solid content in the effluent. Moreover, it worked properly with partially acidified influents meaning a reduction in the chemical reactive expense required to control acid pH‐value throughout operation. © 1999 Society of Chemical Industry     

聚季铵盐对厌氧生化反应器中微生物自身固定化的促进作用

厌氧生化反应器初次启动时培养足量的颗粒污泥需要花费数月甚至1年时间,投加高分子聚合物能够有效地促进厌氧微生物自身固定化的进程,聚合物性能、投加量以及投加方式对厌氧微生物的性能产生影响.通过生物化学甲烷势（BMP）测定原理研究了聚季铵盐的厌氧生物可降解程度;采用厌氧毒性测定(ATA)方法对比了不同浓度下的聚季铵盐对厌氧污泥比产甲烷活性(SMA)和沉降性能的影响.结果表明,适量的聚季铵盐对厌氧微生物自身固定化有促进作用,建议采用间隔9～10d的多次投加方式,厌氧生化反应器中聚季铵盐浓度介于10～20mg•L^-1为宜.     

高负荷厌氧氨氧化反应器的研究进展

剖析了常见的高负荷厌氧氨氧化反应器的构型特点,归纳了颗粒污泥反应器（上流式厌氧污泥床、膨胀颗粒污泥床和气提式反应器）、生物膜反应器和复合式反应器的优缺点。系统总结了高负荷厌氧氨氧化反应器的调控要点,包括操作条件（负荷、回流等）调控、环境条件（pH值、温度、溶解氧等）调控、营养物质（基质比、钙离子浓度、无机碳源等）调控、抑制剂调控和微生物（接种源、优势种、聚集体、生物量和活性等）调控。最后指出,实现高负荷厌氧氨氧化反应器全面应用的关键是突破复杂水质障碍和在低温条件下进行有效调控。     

Effect of coagulation on palm oil mill effluent and subsequent treatment of coagulated sludge by anaerobic digestion

A new effluent treatment scheme is proposed for treating palm oil mill effluent based on coagulation and anaerobic digestion of coagulated sludge. The effectiveness of anionic (N9901) and cationic (N9907) polyelectrolytes manufactured by NALCO (Malaysia) was evaluated both as coagulant and coagulant aid. The results showed that the anionic and cationic polyelectrolytes were best suited as a coagulant aid, and the cationic polyelectrolyte showed better performance than the anionic polyelectrolyte. For an influent chemical oxygen demand (COD) concentration of 59 700 mg L^?1 at an alum dosage of 1700 mg L^?1, the residual COD, suspended solid removal, sludge volume and pH were found to be 39 665 mg L^?1, 87%, 260 mL L^?1 and 6.3, respectively. For the above influent COD and alum dosage with the addition of 2 mg L^?1 of cationic polyelectrolyte as coagulant aid, the results were 30 870 mg L^?1, 90%, 240 mL L^?1 and 6.2, respectively. The sludge resulting from the coagulation process using alum as coagulant and cationic polyelectrolyte as coagulant aid was tested for its digestibility in an anaerobic digester. The quantity of biogas generated per gram of volatile solids (VS) destroyed at a loading rate of 26.7 ± 0.5 and 35.2 ± 0.4 g VS L^?1 d^?1 was found to be 0.68 and 0.72 L g^?1 VS destroyed. The anaerobic biomass when subjected to varying alum dosage in the coagulated palm oil sludge did not exhibit inhibition as the digester performance was in conformity with the regular treatment process Copyright © 2006 Society of Chemical Industry     

Toxic effect of coloured olive compounds on the anaerobic digestion of olive oil mill effluent in UASB-like reactors

Anaerobic sludge digestion of olive oil mill effluent (OOME) in Upflow Anaerobic Sludge Blanket (UASB) reactors was shown to be unstable as a result of both chemical and biological parameters. The study was complicated by the fact that Chemical Oxygen Demand (COD) was removed by growth and maintenance of active biomass and by adsorption in and on the sludge. Coloured compounds caused an inhibition effect on the anaerobic digestion of the wastewater. This inhibition, shown at low COD concentrations of diluted OOME, was due to accumulation of recalcitrant coloured compounds in the sludge, inducing irreversible inhibition of bacterial growth. Partial decolourization of OOME through resin (Duolite XAD 761) treatment reduced the toxic effect.     

厌氧序批式反应器快速形成颗粒污泥技术研究

厌氧序批式反应器(ASBR)初次启动用厌氧消化污泥接种,比较了投加聚季铵盐(A柱)与空白对照(B柱)2个反应器的颗粒污泥形成过程。启动后以每隔2 d投加1次的投加方式向反应器中不断补充聚季铵盐,聚季铵盐投加质量与污泥质量之比取1.6 mg/g。结果表明,A柱颗粒污泥平均粒径达到0.72 mm仅需73 d,比B柱提前了25 d。A柱在启动56 d后COD负荷达到10 g/(L.d),形成的颗粒污泥平均粒径大于B柱(0.55 mm),产甲烷活性也较高。所以投加聚季铵盐能有效促进污泥颗粒化进程。     

Study of saline wastewater influence on activated sludge flocs through automated image analysis

BACKGROUND: In activated sludge systems, sludge settling ability is considered a critical step in effluent quality and determinant of solid–liquid separation processes. However, few studies have reported the influence of saline wastewater on activated sludge. This work aims the evaluation of settling ability properties of microbial aggregates in a sequencing batch reactor treating saline wastewaters of up to 60 g L^?1 NaCl, by image analysis procedures. RESULTS: It was found that the sludge volume index (SVI) decreased with salt content up to 20 g L^?1, remaining somewhat stable above this value. Furthermore, it was found that between the first salt concentration (5 g L^?1) and 20 g L^?1 aggregates suffered a strong deflocculation phenomenon, leading to a heavy loss of aggregated biomass. Regarding SVI prediction ability, a good correlation coefficient of 0.991 between observed and predicted SVI values was attained. CONCLUSION: From this work the deflocculation of aggregated biomass with salt addition due to pinpoint floc formation, dispersed bacteria growth and protozoa absence could be established. With respect to SVI estimation, and despite the good correlation obtained, caution is advisable given the low number of SVI data points. Copyright © 2008 Society of Chemical Industry     

Media configuration and recirculation of upflow anaerobic floating filter for piggery wastewater treatment

An upflow anaerobic floating filter media (UAFF) reactor was applied to the treatment of synthetic and real piggery wastewater. The effect of media configuration and internal recirculation on the system performance was studied. In the first experiment, three-UAFF reactors filled with different media, i.e., polypropylene beads, sponge cubes and coconut fiber were continuously fed with synthetic wastewater at upflow velocity of 0.04 m h⁻¹. The COD removal efficiency in the reactor filled with sponge cubes was highest at 90%, whereas the others filled with polypropylene beads and coconut fibers with lower specific surface area were about 80%. In the second experiment, three-UAFF reactors with sponge were applied to treat real piggery wastewater. COD removal efficiencies were found to be about 80% and methane production rate of 0.26 l l _r ⁻¹d⁻¹. The system performance could be slightly improved by 10% when applying internal recirculation. A sludge blanket (60–70% of total biomass) plays an important role in the system when applied to the treatment of piggery wastewater containing high suspended solid concentration.     

Dry anaerobic batch digestion of the organic fraction of municipal solid waste

Anaerobic digestion at high solid concentrations (dry anaerobic digestion) is an attractive method for the stabilization of solid organic wastes. A new concept for dry anaerobic batch digestion (BIOCEL) of the organic fraction of municipal solid waste is presented. The start up of a BIOCEL reactor was studied with several methods of process set up and operation. Dry anaerobic digestion of the pure undiluted organic fraction obtained from a shredding/separation process was not accelerated by partial spatial separation of substrate and methanogenic inoculum (granular sludge) or leachate recycle, or both. With these three methods after 30 days the high organic acids concentration and low pH in the reactor indicated a sour reactor, unable to establish significant methane production. When the organic fraction was digested in combination with compost addition (40% (w/w) of the initial solids) and leachate recycle, the stabilization rate increased significantly. Leachate recycling in combination with partial spatial separation of the substrate/compost mixture and the inoculum showed the shortest lag phase in the methane production and the shortest digestion time. When the digested residue of a completed digestion was applied as the methanogenic inoculum (40% (w/w) of the initial total solids) the digestion time was slightly shorter. It is concluded that dilution with compost had a positive effect on the start up of the dry anaerobic digestion and compensated for a suboptimal amount of initial methanogenic biomass. During the start up of dry anaerobic batch digestion of municipal solid waste the rapid recovery of methane formation from an initial overloading was observed and was found to be the result of a population shift in the methanogenic biomass and the existence of zones in the reactor with more optimal conditions (higher p H, lower organic acids concentration). The observed digestion time was 36 days. Recommendations are given to shorten the period needed, for complete digestion.     

厌氧氨氧化脱氮技术的研究进展

厌氧氨氧化具有无需外加有机碳源,耗氧量少,污泥产量低等优点,但厌氧氨氧化菌生长缓慢,倍增时间长,抗冲击能力弱,对环境条件要求苛刻,DO、温度、pH、有机物等会对厌氧氨氧化过程产生影响。因此在启动ANAMMOX工艺时,需根据不同水质及处理目的,选择合适的反应器及接种污泥。该文就厌氧氨氧化的发现,反应机理,影响因素,厌氧氨氧化菌的富集、生理生化特征,厌氧氨氧化的启动,厌氧氨氧化工艺等方面做一综述。     

Hydrogen production during the anaerobic acidogenic conversion of glucose

Experiments on hydrogen production using chemostat‐type anaerobic digesters were conducted. The results indicate that the anaerobic acidogenic conversion of glucose can produce hydrogen. The hydrogenic activity of acclimated anaerobic sewage sludge is high at a short solids retention time (SRT) and low pH. At pH 5.7, SRT 0.25 days and an organic loading rate of 416 mmol‐glucose dm⁻³ day⁻¹, each mole of glucose in the mesophilic acidogenic reactor can produce 1.7 mol of hydrogen; each gram of biomass produces 0.456 mole of hydrogen per day. Moreover, the hydrogen productivity of the sludge is comparable to that of an enrichment culture. © 1999 Society of Chemical Industry     

Modeling and Simulation of Activated Sludge Process with Cyclic Feeding for Treatment of Highly Loaded Wastewater

The treatment of strongly loaded wastewater (COD > 1,5 kg m^–3by an activated sludge process (aeration basin + clarifier) depends both on the ability of the activated sludge to remove the soluble organic pollution and on the efficiency of the separation of the treated water from the biomass. The separation ability of the activated sludge notably depends on the hydraulic configuration of the aeration basin: biomass settleability can be controlled by completely mixed reactors (CMR) in series, plug-flow reactors or intermittently fed systems. Moreover, the biomass settleability is linked to the extracellular polymers which are largely composed of microbial exopolysaccharides (EPS). A low level of EPSs indicates a sludge deflocculation problem, whereas a high level of EPSs means that sludge settleability could be hindered because of an excessive growth of filamentous organisms. Experiments show that the use of only one CMR, fed in a cyclic way with permanent oxygenation and return sludge flow, leads to good settleability and effluent quality. The purpose of this paper is to propose a very simple model, based on experiments, in order to optimize the cyclic feeding period by simulations.     

加速厌氧污泥颗粒化研究进展

高效厌氧反应器具有占地面积少、容积负荷高、运行稳定等优点,广泛应用于市政和工业废水处理。厌氧颗粒污泥的快速形成是高效厌氧反应器启动的关键。文章介绍了近年来加速厌氧污泥颗粒化的方法,着重讨论了运行条件的优化、优势菌种的筛选和投加颗粒物、高聚物以及金属阳离子对加速厌氧污泥颗粒化的效果,并对今后研究提出了展望,旨在为厌氧污泥颗粒化的工程应用奠定理论基础。     

Use of anaerobic hybrid reactors for treatment of synthetic pharmaceutical wastewaters containing organic solvents

The performance of anaerobic hybrid reactors treating an organic solvent-containing synthetic pharmaceutical wastewater was evaluated under various wastewater volumetric loading rates and influent compositional changes. The biodegradation, toxicity and treatability of the target C₃ and C₄ solvents, tert-butanol, isopropanol, isobutanol, sec-butanol and ethyl acetate, were examined. At a hydraulic retention time (HRT) of 2 days and volumetric loading rates ranging from 3·5 to 4·5 kg COD m⁻³ day⁻¹, the reactors achieved total and soluble COD removal efficiencies of 97–99% in less than five times the HRT. These removal rates were achieved following the introduction of target solvents not previously supplied to the reactors. However, inadequate removal of tert-butanol resulted in a decrease in the soluble COD removal efficiency to 58%. Bacterial enrichments from the reactor biomass using tert-butanol as the sole substrate proved unsuccessful, confirming that tert-butanol is poorly degradable anaerobically. Inclusion of a trace metal cocktail in the feed did not affect steady-state reactor performance, but was beneficial during changes in the influent composition. After 405 days of operation, the matrix-associated biomass contributed only a minor fraction (2–4%) of the total biomass present in both reactors. On takedown, the retained biomass present in the matrix-free section of both reactors was found to be granular in nature, despite the omission of trace elements from the influent to one of the AHRs. The specific methanogenic activity profile of the granular sludge from the trace element limited AHR was, however, significantly lower (α = 0·05) than that of the reference AHR.     

Anaerobic digestion of alkaline black liquor using an up-flow anaerobic sludge blanket reactor

The anaerobic digestion of alkaline black liquor from a cereal straw pulping mill was studied in batch (serum bottles) and continuous systems (up-flow anaerobic sludge blanket reactor—UASB). The batch digestion studies confirmed that lignin and related compounds (LRC) in the alkaline black liquor were the main inhibitory substances and could not be decomposed by anaerobic bacteria. At organic loading rates of 5–10 kg COD m^?3 day^?1, the UASB reactor achieved 50–60% COD removal efficiencies. Gas production was 2–3 dm³ per dm³ of alkaline black liquor. Two different sludge types were examined in the reactor: granular and cluster-like sludges. Sludge in a cluster, which involved many small granules and flocs, tended to form larger aggregates and possessed good settling ability.     

新型外循环厌氧反应器污泥沉降的数值模拟

结合EGSB及其它厌氧高效反应器的结构特征而开发的新型外循环厌氧反应器,在高上升流速下能有效控制污泥的流失,处理城市污水时获得了良好的效果。为了对新型外循环反应器的污泥沉降性能进行准确模拟和有效控制,利用质量平衡方程与颗粒污泥自由沉降理论,考虑沉降速率与浓度的关系,确定污泥沉降速率,从而建立了该反应器污泥沉降的弥散模型。对不同上升流速下的污泥浓度分布情况进行了模拟,其模拟结果与实测值吻合良好。然后纳入三相分离器分离效率（SE）的概念,实现了对出水SS的模拟,模拟数据的标准偏差小于6%。在确定污泥相对浓度的前提下,利用二次插值预测污泥层高度,结果表明不同上升流速的污泥层高度基本一致,但是同一高度不同上升流速的污泥浓度各不相同。     

High-rate fermentative hydrogen production from palm oil mill effluent in an up-flow anaerobic sludge blanket-fixed film reactor

The major problem associated with UASB reactors for biotransformation of organic matter to hydrogen is the long start-up period (2–4 months) required for the growth of the microbial granules. In this study, an integration of granular sludge system and a fixed film reactor in a single reactor was applied to overcome this problem. An up-flow anaerobic sludge blanket-fixed film (UASB-FF) reactor was initially inoculated with heat pretreated seed sludge as inoculum and operated as closed-loop fed-batch for five days (HRT = 24 h; 38 °C; pH 5.5). The reactor was continuously fed with fresh pre-settled POME in order to shorten the start-up period. The organic loading was gradually increased from 4.7 to 51.8 g/L d. Granular sludge rapidly developed within 22 days. Specific hydrogen production rate was 0.514 L H₂/g VSS d at the end of the start-up period. Speedy development of bio-granules was attributed to biomass recirculation and the establishment of a fixed film at the upper section of the UASB-FF reactor that resulted in improved interactions among the bacterial consortium.     

厌氧-好氧生物处理工艺用于去除水中杀虫剂(英文)

The biodegradability of wastewater containing priority pollutant pesticideVydine or triadimenol(C14H18CLN3O2) in different bio-reactor configurations was investigated.Two laboratory scale biological reactors were employed:one reactor under aerobic condition and the other under anaerobic condition.The aerobic reactor was operated at an ambient temperature(22±2) °C,while the anaerobic reactor was run in the lower mesophilic range(30±2) °C.The effect of pesticide concentration,hydraulic retention time(HRT) ,and co-substrate on the treatment process was explored,using glucose as a supplemental carbon substrate.More than 96%pesticide was removed after an acclimation period of approximately 172 d(aerobic) and 230 d(anaerobic) .The aerobic reactor achieved complete Vydine utilization at feed concentrations up to 25 mg·L-1 .On the other hand,the anaerobic reactor was able to degrade 25 mg·L-1 of Vydine.Moreover,glucose was consumed first throughout the experiment in a sequential utilization pattern.The combination of anaerobic and aerobic biological processes yielded higher biomass concentration and lower retention time than individual units.The biomass in the combined reactors was first acclimated with the corresponding pesticide.Then,the target pesticide,at a concentration of 25 mg·L-1,was sequentially treated in a semi batch mode in the reactors.HRT studies showed that 24 h HRT of aerobic and 12 h HRT of anaerobic were the optimum combination for the treatment of simulated wastewater containing Vydine,which produced Vydine effluent at concentration below 0.1 mg·L-1 .The optimum ratio of substrate(Vydine) to co-substrate(glucose) was 1︰100.