Improvement of upflow anaerobic sludge bed performance using chitosan.

Chitosan, with a degree of deacetylation of 85% and a molecular weight of 2.5 x 10(5) Da, yielding high flocculation efficiency (85 to 100% flocculation) and a broad flocculation region (2 to 45 mg/g suspended solids), was selected for accelerating granulation in a 30-L upflow anaerobic sludge bed (UASB) used to treat wastewater from a tropical fruit-processing industry. Compared with other studies, smaller amounts of chitosan were applied (two injections with 2 mg chitosan/g suspended solids in the reactor at each injection). Comparison with the UASB without chitosan addition, the UASB had a 24 to 37% larger particle size and a 6 to 41% longer solids retention time. In addition, the reactor performances were also enhanced. The UASB with chitosan addition had a 9 to 59% lower effluent chemical oxygen demand (COD), 4 to 10% higher COD removal, up to 35% higher biogas production rate, and a 16 to 68% lower biomass washout. The paired t-test analysis indicated that these performance parameters were significantly different (P < 0.05).     

Influence of ultrasonication on anaerobic bioconversion of sludge.

The influence of ultrasonication on hydrolysis, acidogenesis, and methanogenesis in anaerobic decomposition of sludge was investigated. The sonicated sludge exhibited prehydrolysis and preacidogenesis effects in the anaerobic decomposition process. First-order hydrolysis rates increased from 0.0384 day(-1) in the control digester to 0.0672 day(-1) in the digester fed, with sludge sonicated at 0.52 W/mL. The sonication appeared to be ineffective in relation to acidogenesis reaction rates, but it provided a better buffering capacity to diminish the adverse effect of acidification. Digesters fed with sonicated sludge demonstrated enhanced methanogenesis over the control unit. Determination by coenzyme F420 verified that sonication is able to promote the growth of methanogenic biomass and facilitate a positive methanogenic microbial development in suppressing the initial methanogenesis limitation. The results suggest that ultrasonication could enhance anaerobic decomposition of sludge, resulting in an accelerated bioconversion, improved organics degradation, improved biogas production, and increased methane content.     

厌氧、好氧、厌氧/好氧交替状态对活性污泥性质的影响

实验采用活性污泥处理模拟印染废水,研究厌氧、好氧、厌氧/好氧交替3种条件对活性污泥性质的影响。3种实验条件下,污泥沉降比(SV%)均基本保持在18%~25%之间,污泥容积指数(SVI)保持在62~66 m L/g之间。活性污泥混合液中胞外聚合物(EPS)除EPSB-蛋白质浓度持续升高外,其余形式均呈现积累、达到最大值后下降的趋势,其中厌氧/好氧交替条件下EPS浓度最高而好氧条件下最小。在整个实验期间,活性污泥的脱氢酶活性基本呈上升状态,在厌氧/好氧间歇曝气条件下脱氢酶活性最高、好氧条件次之、厌氧条件最低,最终3种条件下的脱氢酶活性分别为31.27、26.63和24.37 mg/(g·h)。活性污泥中ATP浓度基本呈现先增加后减小、再趋于稳定的变化趋势。实验结果表明,活性污泥表观产率系数顺序是好氧厌氧厌氧/好氧交替运行,厌氧/好氧交替实现了系统内污泥减量,微生物的产率系数和能量状态密切相关。脱氢酶活性对污染物的降解影响明显,而实验条件下微生物能量状态和污泥减量并不对污染物降解产生影响。     

臭氧预处理对剩余污泥特性及厌氧消化的影响

研究了臭氧预处理对剩余污泥特性及厌氧消化的影响,考察了臭氧投加量对污泥特性的影响,并进行了预处理后污泥厌氧消化产气的实验。结果表明,当臭氧处理时间为15 min时,污泥上清液中SCOD含量达到最高为1 006.08 mg·L-1,较未处理污泥提高了420.85%。污泥上清液中蛋白质和多糖含量在臭氧处理时间为10 min时达到最高。氨氮的含量在15 min时达到最大值。三维荧光结果显示随着臭氧投加量的增加污泥中的富里酸类物质有不同程度的减少,在臭氧处理时间为20 min时富里酸类物质减少量最为明显。显微镜和扫描电镜结果显示随着臭氧投加量的增加污泥中的微生物细胞结构受到了不同程度破坏。厌氧消化结果显示当臭氧处理时间为10 min时,污泥产甲烷率达到最高为318.39 mL·（g·VS）-1,较空白对照组提高了396.00%。     

高含固厌氧消化污泥流变特性

采用完全混合式反应器R1、R2和R3(搅拌频率分别设为不搅拌、每10 min转动5 min和每10 min转动8min),在序批式运行的状态下,考察了不同搅拌频率对高含固厌氧消化过程中污泥流变特性的影响,探究了污泥表观黏度降低的主要原因以及污泥流变特性与各项物化指标的关系。结果表明,各个反应器消化污泥表观黏度μ值在发酵的前4天均出现大幅降低,下降幅度依次达到73.3%、77.8%和80.0%,从厌氧装置设计和运行的角度来看,脱水污泥高含固厌氧消化具有可行性。各反应器消化污泥的含固率(total solid,TS)以及挥发性固体(volatile solid,VS)占TS的比例VS/TS与表观黏度μ值以及稠度系数K值呈现显著性的指数关系,而污泥颗粒中胞外聚合物(extracellular polymeric substance,EPS)的含量与污泥表观黏度之间的相关关系则较弱。厌氧消化的初始阶段,微生物(主要是水解菌与产酸菌)的作用是污泥黏度急剧降低的主要原因。     

不同预处理方法对脱水污泥厌氧消化的影响

以城市污水厂脱水污泥为对象,研究不同预处理方法（低温水热、HCl、H2O2、HCl+低温水热、H2O2+低温水热、HCl+低温水热+HAc、H2O2+低温水热+HAc）对污泥可溶化率和后续厌氧消化产气的影响。实验结果表明,HCl添加量越大,pH越低;H2O2添加量越大,污泥可溶化效果越好。H2O2+低温水热+HAc可溶化效果最为显著,经预处理后溶解性化学需氧量（soluble chemical oxygen demand,SCOD）是原泥的13.4倍,溶解性碳水化合物为原泥的4.1倍。可溶化效果与预处理方式均对挥发性脂肪酸（volatile fatty acids,VFA）有影响。预处理条件为HCl+低温水热或H2O2+低温水热时,污泥自身VFA含量有较大幅度增加。生物化学甲烷势（biochemical methane potential,BMP）实验显示,甲烷产率提高与产气高峰提前呈正相关;添加HAc可有效提高微生物对污泥的代谢,有利于甲烷产率的提高。 预处理条件为H2O2+低温水热+HAc时的甲烷产率最大,比原泥甲烷产率提高了57.63%,优于已有研究成果。     

微波辅助改性壳聚糖的制备及其絮凝性能

以壳聚糖、阳离子醚化剂二甲基二烯丙基氯化铵为原材料,采用微波辐射的方法,制备了壳聚糖接枝共聚物（壳聚糖-二甲基二烯丙基氯化铵）,并通过红外光谱分析对改性壳聚糖进行了表征。以接枝率为标准,确定改性壳聚糖的最佳反应条件,并以高岭土悬浊液和实际生活污水作为处理对象,测定了改性壳聚糖的絮凝性能。结果表明,壳聚糖接枝共聚物的最佳制备条件是微波反应温度55℃,反应时间20 min,壳聚糖0.5 g,微波功率270 W,阳离子醚化剂的浓度20%,在此条件下,合成的改性壳聚糖的接枝率为80%。红外光谱分析结果显示,已成功地合成了壳聚糖-二甲基二烯丙基氯化铵接枝共聚物。在絮凝实验中,壳聚糖接枝共聚物的去浊率最高达到91%,COD去除率最高达到77%。其结果表明,壳聚糖接枝共聚物的絮凝性能明显高于原料壳聚糖。     

直接磁场对特定厌氧污泥活性影响的研究

在优势菌生物除铬系统中悬挂表面磁场分别为0～6 mT和0～20 mT的磁片,分别控制磁片之间的磁场强度介于0～4.5 mT和0～14 mT,以未加磁场的对照系统作为参照,考察试验污泥活性的变化.试验结果表明,反应器中磁场强度为0～4.5 mT时,对厌氧活性污泥活性的促进效果较好,最大产甲烷速率(Umax.CH4)达64.3 mL CH4/g VSS·d,比非磁场系统提高20.6%,消耗单位COD产甲烷量为0.140 mL CH4/mg COD,比系统非磁场系统提高70.7%.同时发现了磁场的引入,提高了试验污泥利用COD物质生成甲烷的效率,对于低有机负荷重金属废水的生物净化尤其意义重大.     

生活垃圾渗滤液对厌氧颗粒污泥产甲烷活性的影响研究

通过厌氧毒性实验、恢复实验和特征毒性模拟实验,研究了生活垃圾渗滤液对厌氧颗粒污泥微生物产甲烷活性的影响。结果表明,1 000 mg/L氨氮浓度下产甲烷活性均大于85%,说明相应氨氮浓度范围,垃圾渗滤液基质对厌氧颗粒污泥的微生物没有明显抑制作用。恢复实验后活性得到完全恢复,属代谢毒性。模拟废水氨氮浓度大于1 000 mg/L浓度时,开始出现抑制;氨氮浓度大于3 000 mg/L时,有明显抑制,产甲烷活性下降32.1%;相同氨氮浓度下,渗滤液最大活性区间滞后于模拟废水,产甲烷活性也小于模拟废水,存在除氨氮以外的毒性物质的影响。     

上流式多级厌氧反应器中厌氧颗粒污泥特性研究

高品质厌氧颗粒污泥是厌氧反应器实现高效、稳定运行的关键和基础.在实现上流式多级厌氧反应器(UMAR)处理木薯变性淀粉废水高效运行的基础上,对厌氧颗粒污泥的浓度分布、粒径分布、沉降速度、产甲垸活性,辅酶F420和生物相等作进一步的研究.根据在实验工艺条件下培养得到的厌氧颗粒污泥的性能,探讨厌氧颗粒污泥的可能形成机制.     

Influence of source characteristics, chemicals, and flocculation on chemically enhanced primary treatment.

The overall objective of this research was to investigate various methods and parameters to increase the efficiency of chemically enhanced primary treatment (CEPT). The performance of CEPT was evaluated based on its efficiency of removal of nonsettleable solids (NSS). Some of the source characteristics that influenced NSS concentration included influent total suspended solids, influent turbidity, and influent total chemical oxygen demand. A higher concentration of the influent constituents led to a higher NSS concentration, suggesting that NSS represented a somewhat fixed fraction or percent of these influent constituents. The specific particle surface area (SPSA) was found to correlate with percent NSS in the effluent. A higher SPSA is a result of smaller-sized nonsettleable colloidal particles, thus leading to an increase in percent NSS. In summary, there are several parameters that affect NSS, which could be used to control NSS to improve CEPT, as demonstrated by this study.     

Effects of oxygen exposure on anaerobic digester sludge.

Recuperative thickening of anaerobic digester sludge (thickening with solids return) yields increased digester capacity. Common thickening methods cause oxygen exposure to the digester sludge. This study evaluated the effects of various levels of oxygen exposure on the acetoclastic methanogens. Gravity belt thickening had no detrimental effect on the acetoclastic activity. From a 7-day batch test with continuous oxygen exposure of digester sludge, a 12% loss in acetoclastic activity was predicted for a digester with a 20-day solids retention time (SRT) and 100% recycle with recuperative thickening via dissolved air flotation thickening. However, a greater loss (27%) was found from a long-term, bench-scale digester operated under similar conditions. This loss did not affect the digester performance, as measured by volatile solids destruction. This research suggests that recuperative thickening may not affect digester performance at a long SRT with constant operation, but may change the reserve capacity of the anaerobic community.     

壳聚糖衍生物的合成及其絮凝性能的研究

对从虾蟹壳中制备的壳聚糖进行改性,分别制得壳聚糖衍生物——壳聚糖季铵盐和羧甲基壳聚糖,用于味精废水的絮凝实验。实验结果表明,壳聚糖、壳聚糖季铵盐和羧甲基壳聚糖作为絮凝剂处理味精废水均有较好的效果,以壳聚糖季铵盐的效果最好,其pH值适用范围宽、絮体沉降快,是一种具有良好反应活性的高分子絮凝剂。     

生产性IC反应器厌氧颗粒污泥的生物学特征

IC反应器以絮状污泥接种用于处理酒糟废水,运行至第180d时分别测定反应器第1、第2反应室颗粒污泥的VSS、产甲烷活性、胞外多聚物和辅酶F420等各项生物学指标。结果表明反应器内颗粒污泥具有较强活性,反应器COD去除率基本稳定在95%以上,出水COD不超过1000mg/L。     

The anaerobic biodegradability of municipal sludge and fat, oil, and grease at mesophilic conditions.

The anaerobic biodegradability of municipal primary and secondary sludge with increasing levels of partially dewatered fat, oil, and grease (FOG) was assessed using a mixed methanogenic culture at 35 "C. Under batch conditions with an acclimated and enriched microbial population, the sludge loading was 3 kg volatile solids/m3 and the highest FOG loading tested was 1.5 kg volatile solids/m3, resulting in a methane yield of 245 mL methane/g sludge volatile solids added at 35 degrees C and 1010 mL methane/g FOG volatile solids added at 35 degrees C. Under semicontinuous feeding conditions, the sludge and sludge plus FOG loading tested were 3 and 3.75 kg volatile solids/m3-d, respectively. Within 23 days of operation, the volatile fatty acid concentrations were reduced below 200 mg chemical oxygen demand/L (187 mg/L as acetic acid). Enhancement of sludge digestion was observed in those reactors where codigestion of sludge and FOG took place, which was attributed to a higher level of microbial activity maintained in these reactors as a result of FOG degradation. The results of this study demonstrate that beneficial use of FOG through codigestion with municipal sludge is feasible.     

垃圾渗滤液厌氧处理过程颗粒污泥生长特性

以上流式厌氧反应器为例,研究了渗滤液厌氧处理过程中颗粒污泥的生长特性。结果表明,反应器运行阶段,颗粒污泥粒径由0.96 mm增长至1.06 mm,MLVSS/MLSS大于0.76,污泥能够保持较高的活性。高污泥负荷有利于0.90 mm颗粒污泥生长,0.60~0.90 mm污泥颗粒生长过程中结构不稳定,易发生解体。厌氧颗粒污泥生长过程中,粒径较大的颗粒污泥的孔隙结构较为疏松,它对污泥的活性产生影响。随着孔隙率增大,污泥沉降速度由0.88 cm/s升至0.97cm/s。颗粒污泥表层与内部微生物分布不同,表层微生物以球菌为主,各微生物种群间紧密联系,颗粒污泥内部以短杆菌为主。     

河湖疏浚淤泥的表征、絮凝和脱水

以无锡锡山湿地公园河道淤泥及太湖贡湖湾疏浚底泥为研究对象,对比分析了两种淤泥的矿物组成、粒径分布及泥微粒表面基团、ζ电位等理化特性。以聚丙烯酰胺类聚合物(polyacrylamide,PAM)为絮凝剂,对比分析了其在2种底泥絮凝分离、真空抽滤脱水过程中的作用特征,并对相关影响因素进行了探讨。结果表明,两种淤泥样具有相近的主体矿物组分、有机基团及ζ电位值,但有机质含量稍高的淤泥样中大颗粒所占比例相对较高。相比阳离子型PAM,阴离子型PAM在较少用量下即可获得较大絮团,但上清液浊度较高。絮凝泥在抽滤过程受絮团尺寸影响较大, PAM不同类型基团间的差异对其影响较小,但对趋于平衡后的泥饼含水率略有影响。     

Influence of nutrients on biomass evolution in an upflow anaerobic sludge blanket reactor degrading sulfate-laden organics.

This paper describes the effect of the nutrients iron (Fe), nickel (Ni), zinc (Zn), cobalt (Co), and molybdenum (Mo) on biomass evolution in an upflow anaerobic sludge blanket (UASB) reactor metabolizing synthetic sulfate-laden organics at varying operating conditions during a period of 540 days. A bench-scale model of a UASB reactor was operated at a temperature of 35 degrees C for a chemical oxygen demand-to-sulfate (COD/SO4(2-)) ratio of 8.59 to 2.0, a sulfate loading rate of 0.54 to 1.88 kg SO4(2-)/m3 x d, and an organic loading rate of 1.9 to 5.75 kg COD/m3 x d. Biomass was characterized in terms of total methanogenic activity, acetate-utilizing methanogenic activity, total sulfidogenic activity, acetate-utilizing sulfidogenic activity, and scanning electron microscopy (SEM). Nickel and cobalt limitation appears to affect the activity of hydrogen-utilizing methane-producing bacteria (HMPB) significantly without having an appreciable effect on the activity of acetate-utilizing methane-producing bacteria (AMPB). Nickel and cobalt supplementation resulted in increased availability and, consequently, restoration of biomass activity and process performance. Iron limitation and sulfidogenic conditions resulted in the growth of low-density, hollow, fragile granules that washed out, causing process instability and performance deterioration. Iron and cobalt supplementation indicated significant stimulation of AMPB with slight inhibition of HMPB. Examination of biomass through SEM indicated a population shift with dominance of sarcina-type organisms and the formation of hollow granules. Granule disintegration was observed toward the end of the study.     

剪切应力对活性污泥絮体特征的影响

采用具有自动控制系统可周期性改变搅拌速度的生物反应器处理生活污水,研究了剪切应力周期变化对活性污泥絮体特征及功能菌群分布的影响。结果表明,在相同的运行条件下,运行初期的污泥形态不规则,结构疏松,其内部各功能菌群丰度差异较大,污泥絮体粒径受剪切应力影响较大,最大和最小剪切应力下污泥平均粒径相差30μm;随着反应器运行时间的延长,活性污泥絮体的粒径减小;到达运行稳定期,污泥粒径较小,但结构紧实,最大和最小剪切应力下污泥平均粒径相差仅为6μm,说明剪切应力对污泥粒径的影响减弱,其主要作用在于维持污泥絮体相对稳定的三维结构及相对平衡的功能菌群分布。此外,处理效果研究也表明,稳定的污泥结构有助于污染物去除效率的提高。