Study on Limited Filamentous Sludge Bulking Test in A/O Activated Sludge Process

[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explored by changing the DO con- centration in the aerobiotic pool of NO system from the low load （0.25 kg COD/（kg MLSS.d）） and the medium to high load （0.55 kgCOD/（kg MLSSod））. [Result] In the NO activated sludge system, when the sludge load was 0.25 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was at around 250, while when the sludge load- ing was 0.55 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was close to 300, occurring the limited filamentous bulking. The bulked sludge still showed high removal rates to COD, SS, nitrogen and phosphorus. [Conclusion] It could improve the oxygen transfer rate and reduce the aeration rate at low DO conditions to achieve energy-saving.

Static aerobic composting of municipal sewage sludge with forced ventilation:Using matured compost as bulking conditioner

Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated. Physical and chemical parame ,eters, e.g., temperature, moisture content, VSS, CODcr, pH, and germination index （GI）, were analyzed to characterize the composting process. Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d, owing to the bulking function of matured compost. Compared to air ventilation, however, forced ventilation enables the high-temperature stage to last longer for approximately 7 d. The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation, and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition. Although no obvious differences of VSS and pH are observed between both compost heaps, the soluble CODcr and GI show differences during the second half period of fermentation. In forced ventilation compost, the soluble CODcr has a small rebound after 13 d, and GI decreases from 46% to 35% but then increases. These results show that in general, the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.

Negative Effects of Sludge Bulking in Membrane Bio-Reactor

Sludge bulking property of membrane bio-reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in membrane bio-reactor increased slightly through the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures, the high block rate of membrane pore and the great quantity of filamentous bacteria at the external surface presented at the same time. Thus, plenty of methods should be performed to control sludge bulking once it happened in membrane bio-reactor.

Sludge Bulking Property of Membrane Bio-reactor in Albumen Wqastewater Treatment

Albumen wastewater was treated by Membrane Bio-reactor. Sludge bulking property of Membrane Bio-Reactor was investigated in this study through contrast research. When the sludge bulking appeared, the removal efficiency of COD in Membrane Bio-reactor increased slightly under the function of filamentous bacteria. However, the negative effects of the higher net water-head differential pressures,the higher block rate of membrane pore and the great quantity of filamentous bacteria at the externalsurface pres...

Characteristics of Nutrients Removal under Viscous Sludge Bulking Treating Synthetic Wastewater

Viscous sludge bulking is a rare phenomenon in activated sludge process.The performances of nutrients removal were investigated with normal sludge and viscous bulking sludge.The results showed that when COD loading and C/N ratio were around 0.13 mg COD/(mg MLSS·d)and 7.67,the effect of viscous sludge bulking on the maximum specific oxidation rates of NH_(4)^(+)⁃N was very little,while the maximum specific oxidation rates of NO_(2)^(-)⁃N decreased from 24.69 mg/(g·h)to 1.20 mg/(g·h).Compared with normal sludge,viscous bulking sludge had bigger particle size and more extracellular polymeric substances(EPS).The mass transfer resistance in sludge flocs might be the main cause of the difference in NO-2⁃N oxidation rates.Therefore,this study demonstrates that viscous sludge bulking is beneficial to enhance simultaneous nitrification and denitrification(SND),and excessive EPS will exhibit storage function during phosphorus removal process.

The Use of Ultrasonics in the Treatment of Waste Activated Sludge

The present paper reports on extensive investigations using an ultrasomc treatment ot WAS, to study its potential to meet one or all of four objectives： （1） reduce WAS quantities; （2） achieve a better dewaterability; （3） provoke a release of COD from the biosolids, preferably transformed into biodegradable organics and （4） possibly destroy the filamentous micro-organisms responsible for sludge bulking. The experiments are carried out in a batch reactor of volume up to 2.3L. The ultrasonic apparatus consisted of a generator, a converter and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different sludge kinds were tested, at approximate concentration （DS/WAS） between 3.5 and 20g·L^-1. The release of COD from the WAS-phase into the filtrate phase is a function of the specific energy-input SE with yields of about 30% achievable at SE-values of 30000 kJ·kg^-1. A major fraction of the COD is transformed into biodegradable organics （BOD）. The reduction of DS-fraction of the sludge is equivalent to the COD-release rates. Although the dry solids content （DS） is reduced, the dewaterability of the sludge is not improved. This reflects itself in a slightly decreased dryness of the filter cake using vacuum filtration, and in increased values of the capillary suction time （CST）. This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area. More surface water is bound （CST increases） and the filterability decreases due to clogging of the cake. To reach the same dryness as the untreated cake, the required dosage of poly-electrolyte increases proportionally with the level of ultrasound energy supplied. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. Especially the release of COD and its transformation into BOD certainly merit further research.

Physicochemical Properties of Sewage Sludge from Gaza

This study characterized the physicochemical properties of sewage sludge collected from Gaza wastewater treatment plant. Sludge samples were collected from the drying beds, air-dried, sieved through 2 mm and stored in plastic bags at room temperature. Sludge density, particle size distribution, water holding capacity, void volume, pH, EC, total organic carbon and hydrophobicity were determined. Results showed the bulk density is about 1.18 g/cm3 whereas the real density is 2.12 g/cm3 and void volume is 50%;Particle size distribution showed that the major size of sludge is sand-like size (630 - 200 μm) and the minor size is silt-like size (200 - 20 μm) and clay-like size is less than 20 μm. Sludge has an acidic pH reaction (6.78 ± 0.02) with an electric conductivity equal to (2.49 ± 0.04) mS?cm-1. The hydrophobicity of sludge is very high, water drop penetration time (WDPT) is 114.77 ± 18.78 sec with a radius of 0.44 ± 0.08 cm. In the way around, oil drop penetration time (ODPT) of sludge is 5.05 ± 1.28 sec with a radius of 1.25 ± 0.14 cm. The WDPT/ODPM ration has very high value 22.73 indicating extreme hydrophobicity. High value of hydrophobicity may reduce water filtration in soil when sludge applied for agriculture. These results suggest that sludge application to soil may change the physicochemical properties of soil.

Effect of Deionization on Activated Sludge Characteristics: A Case Study of Activated Sludge Culture with Tap Water and Distilled Water

Activated sludge dewaterability and settleability properties are of prime importance in sludge treatment and disposal. Herein, we have experimentally examined the effect of deionization on activated sludge characteristics taking a case study of activated sludge inoculated in tap water and distilled water. The quality of the effluent, both distilled water and tap water were analyzed to determine the characteristics of activated sludge. Results indicated the increasing of the sludge volume index from 51.67 ml/g to 146.9 ml/g leading to the sludge bulking for sludge inoculated in distilled water. The Capillary Suction Time (CST) of sludge cultivated in distilled water varied from 23.1 to 38.4 s, which suggests poor dewaterability. These are due to the growth of some filamentous bacteria in distilled water system. These have further confirmed by light microscope images that showed a significant difference between the sludge systems cultivated in tap water and those grown in distilled water. The present work indeed advances our understanding of activated sludge treatment and would serve as a handy reference for researchers or scholars who want to deal with sewage water treatment.

城市污水处理过程污泥膨胀识别与抑制综述

污泥膨胀是活性污泥法污水处理过程中常见的一类异常工况,且具有严重危害性,研究污泥膨胀的识别和抑制方法对城市污水处理过程正常运行意义重大.本文主要针对城市污水处理过程中污泥膨胀的识别和抑制方法进行综述.首先,文章概述了城市污水处理过程,介绍了污泥膨胀的概念、主要特点、类型和成因;其次,概述了基于微生物生理特征、机理模型、图像识别和数据驱动的污泥膨胀识别方法,分析其发展现状并指出优缺点;然后,概述了基于过程调控和机理特征的污泥膨胀抑制方法,分析其发展现状并对比优缺点;最后,总结全文,指出了城市污水处理过程污泥膨胀识别和抑制面临的主要问题,并对其研究趋势进行了展望.

基于自适应宽度学习算法的城市污水处理污泥膨胀识别

针对污水处理过程的污泥膨胀难以精准识别的问题,提出了一种基于自适应宽度学习算法(adaptive broad learning algorithm,ABLA)的污泥膨胀识别方法。首先,结合城市污水处理过程的运行数据,采用主元分析法选取与污泥体积指数(sludge volume index,SVI)相关的特征变量;其次,建立了一种基于ABLA的污泥膨胀识别模型,利用自适应伪逆算法更新模型参数,提高了识别精度,并验证了模型的收敛性;最后,将所提模型应用于实际的污水处理过程中,利用污水处理厂的实际运行数据对其进行实验验证。实验结果表明,基于ABLA的污泥膨胀识别模型能够实现污泥膨胀的精准识别。

群体感应与群体淬灭控制丝状菌污泥膨胀的研究进展

活性污泥法净化污水过程中,丝状菌的过度生长导致污泥膨胀。利用微生物群体感应机制是控制丝状菌膨胀的一种新兴策略。介绍了丝状菌膨胀的控制策略及微生物群体感应的作用机制,综述了群体感应与群体淬灭控制丝状菌膨胀的研究进展,分析了其影响因素并提出未来研究方向,为控制丝状菌污泥膨胀提供一种新的理论思路。

A^(2)O工艺活性污泥黏性膨胀原因及控制措施

污泥黏性膨胀问题一直是A^(2)O工艺运行控制的难点。郑州市某污水处理厂在运行过程中出现污泥黏性膨胀问题,造成污泥沉降性能变差,SVI逐渐提升至240 mL/g左右,二沉池泥位持续升高。从进水水质、水温、曝气量、浮渣等多方面综合分析引起污泥膨胀的原因,及时从剩余污泥排放量、污泥龄、溶解氧、回流比、水力停留时间等工艺参数调整运行工艺,使污泥膨胀问题得到一定程度的缓解。为彻底消除生物池浮泥,又通过在二沉池配水井精准投加40 mg/L的阳离子高分子絮凝剂,经过一段时间的药剂助沉,明显提高了污泥沉降性能,SVI也逐渐下降至120 mL/g左右的正常水平,解决了污泥黏性膨胀问题,消除了生物池浮泥,为解决污泥黏性膨胀提供了思路。

Bulking sludge for PHA production:Energy saving and comparative storage capacity with well-settled sludge

Two acetate-fed sequencing batch reactors （SBR） were operated under an aerobic dynamic feeding （ADF） model （SBR#2） and with anaerobic phase before aerobic phase （SBR#1） to select mixed cultures with a high polyhydroxyalkanoates （PHA） storage response. Although kinetic selection based on storage response should bring about a predominance of floc-formers, a bulking sludge with storage response comparable to well-settled sludge was steadily established. An anaerobic phase was introduced before the aerobic phase in the ADF model to improve the sludge settleability （SBR #1）, however, due to the consequent increased feast/famine ratio, the performance of SBR #1, in terms of both the maximum PHB （polyhydroxybutyrate） cell content and APHB, was lower than that of SBR #2. SBR #2 gradually reached a steady state while SBR #1 failed suddenly after 50 days of operation. The maximum specific substrate uptake rate and storage rate for the selected bulking sludge were 0.4 Cmol Ae/（Cmol X.hr） and 0.18 Cmol Ac/（Cmol PHB.hr）, respectively, resulting a yield of 0.45 Cmol PHB/（Cmol Ae） in SBR #2 in the culture enrichment phase. A maximum PHB content of 53% of total suspended solids and PHB storage rate of 1.36 Cmol Ac/（Cmol PHB.hr） was achieved at 10.2 hr in batch accumulation tests under nitrogen starvation. The results indicated that it was feasible to utilize filamentous bacteria to accumulate PHA with a rate comparable to well-settled sludge, Furthermore, the lower dissolved oxygen demand of filamentous bacteria would save energy required for aeration in the culture enrichment stage.

Analysis of bacterial community in bulking sludge using culture-dependent and -independent approaches

The bacterial community of a bulking sludge from a municipal wastewater treatment plant with anoxic-anaerobic-oxic process was investigated by combination of cultivation and 16S rRNA gene clone library analysis for understanding the causes of bulking.A total of 28 species were obtained from 63 isolates collected from six culture media.The most cultivable species belonged to γ-Proteobacteria including Klebsiella sp.,Pseudomonas sp.,Aeromonas sp.and Acinetobacter sp.Further analysis of these strains by repetitive sequence based on polymerase chain reaction （rep-PCR） technology showed that rep-PCR yielded discriminatory banding patterns within the same genus using REP and BOX primer sets.While the culture-independent assessment revealed that β-Proteobacteria was the dominant group in the bulking sample.Sequence analysis revealed that the highest proportion （14.7%） of operational taxonomic units was 98% similar to Candidatus Accumulibacter phosphatis,which is used to remove phosphorous from wastewater.Our results indicated that combining different approaches can produce complementary information,thus generate a more accurate view of microbial community in bulking sludge.

A^(2)/O工艺Microthrix parvicella型微膨胀污泥微生物群落特征

为探究Microthrix parvicella引发的污泥膨胀微生物群落特征,采用A^(2)/O工艺并借助高通量测序技术,考察污泥膨胀中微生物群落整体、硝化菌群和丝状菌群的变化特征。结果表明,当系统运行温度由24℃降低为14℃并运行21 d后诱发了M.parvicella污泥膨胀,污泥体积指数由81 mL/g升高至197 mL/g,系统中COD和NH^(+)_(4)-N的平均去除率分别为84%和98%。污泥膨胀使微生物群落结构发生变化,Actinobacteria门相对丰度由8%增大到20%,优势地位明显提升,Proteobacteria门和Nitrospirae门相对丰度降低。低温下AOB、Nitrospira丰度降低,Nitrobacter丰度升高,但系统内仍存在一定数量的硝化菌群,这维持了良好的硝化效果。丝状菌群中M.parvicella、Thiothrix和Flavobacterium相对丰度升高,其余8种丝状菌属相对丰度降低。升高温度后,污泥膨胀得到控制。

造纸废水活性污泥的微生物群落结构及多样性分析

为探究造纸废水活性污泥中微生物群落结构多样性以及对造纸废水处理效果的影响,利用Illumina MiSeq高通量测序方法,分析在处理造纸废水过程中,同一运行阶段两个并联氧化沟内活性污泥的微生物群落与多样性组成。结果表明,系统中处理造纸废水的活性污泥在同一废水条件下微生物群落结构总体稳定,优势细菌为绿弯菌门(Chloroflexi)、拟杆菌门(Bacteroidota)、变形菌门(Proteobacteria)、Myxococcota、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)等。最重要的优势细菌类群为Chloroflexi,相对丰度占比为47.67%~48.22%,远远高于其他废水中Chloroflexi的占比,其中厌氧绳菌纲(Anaerolineae)是其主要成员,占比84.39%~88.34%,可针对性地去除造纸废水中的污染物。造纸废水活性污泥样品中存在大量特殊功能菌群,其在废水中污染物尤其是木质素的去除中发挥着重要作用。

膨胀污泥中主要丝状菌及生物调控措施研究进展

通过总结文献发现,不同地区造成污泥膨胀的丝状菌类似,包括Ca.M.parvicella、Thiothrix、H.hydrossis、Ca.Amarolinea等,其中以Ca.M.parvicella为主。温度过低、pH过低、溶解氧浓度不足、污泥负荷过低、氮磷等营养物质含量不足等均可能导致丝状菌的大量繁殖并引发污泥膨胀。结合研究现状重点介绍了利用群体感应相关技术控制污泥膨胀的方法,并提出相关技术的发展方向,为活性污泥法稳定运行和科学管理提供理论依据。

利用微藻黏附生长特性恢复丝状菌引起的污泥膨胀现象

针对丝状菌引起的污泥膨胀问题,将膨胀污泥接种在序批式光照反应器内,再接种不同比例的微藻,利用微藻黏附生长特性对膨胀污泥的沉降性能进行恢复。研究结果表明:在投加不同比例的微藻后,膨胀污泥的沉降性能恢复良好,污泥容积指数(SVI_(5))值达到14.98 mL/g,污泥粒径最大增长到103.36μm。恢复了沉降性能的污泥有较高的胞外聚合物质量比。此外,微藻的加入也提升了膨胀污泥的污染物去除性能,其对化学需氧量(COD)的去除率为73.0%,对氨氮(NH^(+)_(4)-N)的去除率为43.6%,对总无机氮(TIN)的平均去除率为37.7%,对总磷(TP)的去除率为84.2%。在膨胀污泥沉降性能恢复过程中,胞外聚合物中蛋白质的质量比最高上升至26.89 mg/g挥发性悬浮物(VSS),而多糖的质量比基本稳定在9.09 mg/g VSS左右。

基于显微图像定量分析的污泥体积指数预报

污泥体积指数(SVI)是评价活性污泥沉降性能的一个重要参数。传统SVI测量依赖实验室化验分析,繁琐、耗时,难以实现污泥质量的实时监视和闭环控制。本研究旨在利用活性污泥显微图像的定量分析开发可靠且稳定的SVI预报方法。该方法通过相位一致性原理抑制相差效应,使用相位拉伸变换和阈值分割方法分割丝状菌和絮体目标,并表征和提取与SVI相关的形态学特征。最后,通过皮尔逊相关系数法选择特征参数子集,构建动态随机配置网络SVI预报模型。以某污水处理厂A2O工艺为背景,进行了实验验证。实验结果表明所提方法的可行性和有效性。

A^(2)O工艺系统丝状菌膨胀原因分析及对策

构建A^(2)O工艺系统以探究生活污水处理中丝状菌膨胀的主要原因及有效控制措施,试验结果表明,缺氧池(A2池)由于池水搅拌不均,底部污泥腐化严重导致贝日阿托氏细菌(Beggiatoa)膨胀;好氧池(O池)由于低温条件下的高浓度进水负荷导致微丝菌(Microthrix parvicella)膨胀;采用传统停水闷曝、添加NaClO试剂等措施并不能实现迅速有效控制丝状菌膨胀的目标。通过采用空床饥饿调试、提高氧传质效率、改变污泥絮体结构等措施,能够快速有效抑制丝状菌膨胀,并恢复菌胶团生长优势,重构生活污水生物处理系统。