磷酸钙盐法回收剩余污泥超声波处理上清液中磷的研究

在污泥减量化处理中,细胞微生物中的碳氮磷等会释放到上清液中。为了对上清液中的磷进行有效回收,在前期研究的基础上,以生物厌氧好氧除磷(An/O)工艺的剩余污泥超声波处理上清液为研究对象,考察了磷酸钙盐(HAP)法的磷回收效果。结果表明:HAP法反应较快,5 min时反应基本完成;初始pH值在8.5～10.0时,回收率均可保持在较高水平;最佳钙磷比(Ca2+/PO34--P)为3.87。在以上最佳工艺条件下,总磷(TP)、正磷酸盐(PO34--P)的回收率分别达到88.4%、94.0%,同时对上清液中的有机物、氮也有一定的去除。     

Biohydrogen production using waste activated sludge as a substrate from fructose-processing wastewater treatment

Biohydrogen production by dark fermentation in a series of batch tests under different environmental control conditions was evaluated to determine the optimal initial cultivation pH and temperature for a continuous-flow kinetic test to validate the kinetic model system. The waste activated sludge (WAS) from fructose-processing manufacturing was used as the model substrate for biohydrogen production. The batch experiments for biohydrogen production were conducted in a 6 l bioreactor. Fifteen batch kinetic tests were investigated when pH was controlled at 6, 7, 8 and 9 as well as the temperature was controlled at 37 °C, 45 °C and 55 °C, respectively. The experimental results indicated that the optimal operational condition for hydrogen production occurred while pH was 7 and temperature was 55 °C with the highest hydrogen production of 7.8 mmol. The optimal recovery time for hydrogen was 25 h in the batch experiments. Furthermore, the kinetic test of biohydrogen production was performed by anaerobic mixed microbial culture in the continuous-flow experiment when pH and temperature was maintained at 7 and 55 °C. Approximately 60% and 7% of substrate solution was converted into acetate and hydrogen, respectively, at the steady state. Roughly only 0.77% and 2.7% of substrate solution was converted into propionate and butyrate, respectively, at a steady-state condition. The experimental and modeling approaches presented in this study could be employed for the design of pilot-scale and full-scale anaerobic biohydrogen fermentors using food-processing waste activated sludge (WAS) as a substrate solution.     

碱对含油污泥超临界水氧化的影响研究

在间歇反应釜中进行含油污泥超临界水氧化试验,反应压力为25 MPa,反应温度为390～450 ℃,反应时间为1～10 min条件下,研究添加Na2CO3和NaHCO3对含油污泥超临界水氧化的影响.结果表明,添加Na2CO3和NaHCO3均有利于COD的去除,且NaHCO3的处理效果优于Na2CO3.NaHCO3的适宜添加质量浓度为100 mg/L,且低温下的处理效果优于高温,而高温甚至起到了抑制作用.在390 ℃、25 MPa、NaHCO3添加质量浓度100 mg/L、过氧量427%条件下,反应5 min后含油污泥的COD去除率达86%,比添加前提高了10.7%,同时也降低了中间产物CO和醋酸的收率.本研究为开发超临界水氧化含油污泥无害化处理新技术和新方法提供了参考.     

超临界水中含油污泥与甲醛共氧化研究

在温度为390～450 ℃,压力为25 MPa,反应时间为1～10 min的条件下,在间歇式反应釜中采用超临界水共氧化方法处理含油污泥,考察共氧化添加物种类、时间、甲醛质量浓度和温度对氧化效果的影响.结果表明,添加甲醛对含油污泥的转化具有明显的促进作用,450 ℃反应10 min,含油污泥COD去除率达99.0%.甲醛质量浓度至少要与含油污泥初始COD处于同一数量级时,才具有显著的促进作用.氧化中间产物CO和醋酸产率随甲醛质量浓度提高而增加.反应温度低时甲醛的促进作用明显.随着反应温度的提高,CO产率增加,醋酸产率降低.     

油田含油污泥掺煤资源化试验研究

为使含油污泥和煤混烧在实际工程中得到应用,实现含油污泥资源化,对含油污泥和煤进行工业分析、元素分析,并对含油污泥的重金属浸出液特性进行分析,同时研究了含油污泥的燃烧特性.结果表明,含油污泥燃烧过程主要分为2个阶段,其中第1阶段为脱水干燥和挥发分析出阶段,在差热分析曲线(DSC曲线)上存在1个吸热峰和1个放热峰,含油污泥减少质量可达75％;第2阶段为挥发分燃烧和固定碳燃烧阶段,在DSC曲线上有1个放热峰,含油污泥的总失重率为92.86％,充分实现了减量化.探讨了掺煤量、粒径和煤种等因素对型煤燃烧性能的影响,发现与含油污泥直接燃烧相比,污泥与大同煤按1∶4质量比混合制得的粒径为15 mm的污泥型小球在马弗炉中燃烧时,起燃时间早,燃烧时间较长,且火焰长度适中稳定,黑烟产生量少,燃烧性能明显改善,同时能够满足在链条炉中燃烧的要求,使含油污泥资源化利用效果更好.     

市政污泥掺烧对生活垃圾焚烧设施烟气中污染物排放的影响

与生活垃圾协同焚烧是污泥处置中最有前景的处置方式,但其对焚烧烟气污染物排放的影响尚未明确。利用生活垃圾焚烧炉开展生活垃圾协同处置市政污泥的试验,研究掺烧5%、10%和15%的市政污泥时焚烧烟气中酸性气体、烟尘、重金属和二噁英等的排放特征。结果表明:与单独焚烧生活垃圾的对照组相比,在各掺烧比例下,烟气中SO_2、HCl、NO_x及烟尘有一定程度的增加,但均未超过GB18485—2014《生活垃圾焚烧污染控制标准》限值;Cu、Hg排放质量浓度明显下降,Cr、Cd波动下降,Pb在高掺烧比时仍远低于限值,Ni增长幅度小于15%;二噁英总量升高,但仍符合标准限值。因此,在掺烧比例不超过15%的情况下,焚烧烟气中污染物排放仍在安全可控范围。     

Disintegration of waste activated sludge by different applications of Fenton process

Oxidative disintegration of municipal waste activated sludge (WAS) using conventional Fenton (Fe²⁺ + H₂O₂, CFP) and Fenton type (Fe⁰ + H₂O₂, FTP) processes was investigated and compared in terms of the efficiency of sludge disintegration and enhancement of anaerobic biodegradability. The influences of different operational variables namely sludge pH, initial concentration of Fe²⁺ or Fe⁰, and H₂O₂ were studied in detail. The optimum conditions have been found as catalyst iron dosage = 4 g/kg TS, H₂O₂ dosage = 40 g/kg TS and pH = 3 within 1 h oxidation period for both CFP and FTP. Kinetics studies were performed under optimal conditions. It was determined that the sludge disintegration was happened in two stages by both processes: rapid and subsequent slow disintegration stages and rapid sludge disintegration stage can be described by a zero-order kinetic model. The effects of oxidative sludge disintegration under the optimum conditions on anaerobic digestion were experienced with biochemical methane potential (BMP) assay in batch anaerobic reactors. Total methane production in the CFP and FTP pre-treated reactors increased by 26.9% and 38.0%, relative to the untreated reactor (digested the raw WAS). Furthermore, the total chemical oxygen demand reductions in the pre-treated reactors were improved as well.     

New method for acrylic acid recovery from industrial waste water via esterification with 2-ethyl hexanol

Acrylic acid (AA) is an important component for the production of acrylate polymer. In a typical acrylic manufacturing unit, waste water contains AA in a range of 4–15 wt.% contributes to the high values of chemical oxygen demand. Due to the toxicity of AA to the aquatic organism, this wastewater should be treated before it is discharged to the environment. The waste water could be evaporated before sending to the incineration which was neither economic feasible nor environmental friendly. Esterification of wastewater containing carboxylic acid with alcohol could be a promising method to recover the acid by converting it to ester while purifying the wastewater. In the present study, recovery of AA via esterification with 2-ethyl hexanol (2EH) was investigated. The model industrial wastewater with various concentration of AA (10–100% w/w) was reacted with 2EH to produce 2-ethyl hexyl acrylate (2EHA) in the setups with total reflux and continuously water removal. These Amberlyst-15 (ion exchange resin) catalyzed reactions were carried out under the mass transfer resistance free region. The performance of both systems was compared. The yield for the reactions of the AA solutions with the AA concentrations of 30–80% was enhanced significantly when the reactions were carried out using the second setup. The kinetic data of the esterification of dilute AA was well described by the Eley–Rideal (ER) kinetic model incorporated with a correction factor to consider the catalyst fouling effect and pseudo-homogeneous (PH) kinetic model for the AA polymerization. The findings have shown the potential of recovering AA from the waste water stream via esterification. The concentrated AA solutions or larger amount of inhibitor should be adopted to prevent the catalyst fouling by the deposition of poly-acrylic acid on the catalyst surface.     

Physical and chemical characteristics of waste activated sludge treated with electric field

This study investigates the physical and chemical characteristics of sludge treated with controlled levels of electric field. The results indicated that the potential gradient and contact time strongly influenced the physical and chemical characteristics of sludge. Based on the settling velocity measurements, a potential gradient of 6 V/cm with a treatment time of 10 min is recommended as an optimal condition for improving sludge settling. For sludge disintegration, applying a higher potential gradient and a longer treatment time to the sludge are more efficient than applying lower levels. The results of the experiments presented here show that an electric field not only disintegrates sludge and destroys microbial cells but also removes and solubilizes organic substances. Possible mechanisms of electric field treatment are also discussed.     

Phosphate removal using aerobic bacterial consortium and pure cultures isolated from activated sludge

In the present study, an attempt is made to evaluate the kinetics of biological phosphate removal using a bacterial consortium of activated sludge, as well as screening for dominant polyphosphates accumulating bacteria. The results showed an efficient phosphate uptake (P < 0.001) of the consortium, with rates related to the initial concentration of both phosphate and carbon sources. Short chain volatile fatty acids presented the suitable substrates for enhanced biological phosphorus removal, of which maximum yield reached 99.23% and 78.51% in basal salt medium supplemented with 0.5% of sodium acetate and lactate respectively. Fifteen phosphate-accumulating bacteria were isolated from the activated sludge and only four isolates were selected and characterized as Pseudomonas aeruginosa AS1, Moraxella lacunata AS2, Acinetobater junii AS3 and Alcaligenes denitrificans AS4. The highest efficiency of phosphate uptake using pure culture was achieved with Ac. junii AS3 (83.36) followed by P. aeruginosa AS1 (81.78%), Al. denitrificans AS4 (76.72%), and M. lacunata AS2 with 50.6%.     

氧化预处理对污泥蛋白质提取及脱水性的影响

为了提高污泥蛋白质的提取效率并提高其脱水性,分别采用过硫酸氢钾、过氧化钙及被Fe2+活化后的过硫酸氢钾和过氧化钙预处理污泥,以考察其对污泥脱水性及蛋白质提取效率的影响并选出一种最佳的氧化预处理方式.结果表明,过硫酸氢钾和过氧化钙单独调理时,污泥脱水性有明显提高且蛋白质提取量较高.经Fe2+活化后,虽然污泥比阻(FSR)比单独调理时降低50％以上,但因反应生成具有絮凝效果的Fe3+导致蛋白质提取量大幅降低.结合蛋白提取效率,发现采用0.1 g/gTSS(干物质质量)的过氧化钙单独调理效果最好,此时污泥比阻(FSR)与毛细吸水时间(tCST)分别为0.37×1013m/kg、22.4 s,相比原污泥比阻与毛细吸水时间分别降低78.4％和76.6％,同时蛋白质提取量高达104.52 mg/g TSS,与原污泥相比增加了 80.4％.     

DNA提取方法对活性污泥微生物多样性PCR-DGGE检测的影响

评价超声波法、2种基于SDS的裂解法、改进的化学裂解法、微波法和冻融 玻璃珠 溶菌酶 SDS等6种DNA提取方法对活性污泥微生物多样性PCR-DGGE检测的影响.结果表明,2种不同的DNA纯化方式(溶液和胶纯化)及PCR扩增方式(直接和巢式PCR)对DGGE结果没有明显的影响,但不同的DNA提取方法对DGGE结果有明显的影响,其中2种基于SDS裂解法的DGGE条带较多,其提取的DNA产量(14.85μg/g湿重)和纯度(OD260:OD280＞1.80)也最高;改进的化学裂解法和微波法次之;超声波法、冻融 玻璃珠 溶菌酶 SDS法较少.研究表明,DNA提取方法是影响活性污泥微生物多样性PCR-DGGE检测结果的关键因素,基于SDS的裂解法是用于活性污泥微生物多样性PCR-DGGE研究的一种简便、可靠的总DNA提取方法.     

生活污泥干化与生活垃圾协同焚烧研究分析

我国城市化的快速发展导致城市人口的迅速膨胀,城市生活污水产生量也迅速增加,在污水处理过程中自然而然的产生了大量的污泥。据不完全统计,每年一座中等城市产生的污泥量大约在25~30万t。本文通过对生活污泥干化的研究与生活垃圾协同焚烧的研究,有助于形成积极的公众舆论和认同,为垃圾协同污泥焚烧技术在全国的推广实施提供便利。     

Solvent design and inherent safety assessment of solvent alternatives for palm oil recovery

The concept of inherent safety is important in developing an inherently safer and user-friendly process. This paper discusses a new integrated approach of computer-aided product design and inherent safety assessment. Computer-aided Molecular Design (CAMD) approach was utilized in this work to identify potential alternative to n-hexane, the widely used industrial solvent in extracting residual palm oil from pressed palm fibre. The formulation of solvent mixtures was optimized to meet the targeted physical properties before being tested using the Soxhlet Extraction method. Inherent safety assessment to assess the solvent's flammability, toxicity, reactivity, and explosiveness was conducted on the new solvent mix, Mixture 1 (n-hexane + ethanol), Mixture 2 (n-hexane + acetone) and Mixture 3 (n-hexane + n-butanol). It was found that Mixture 1 and 3 are safer than n-hexane and able to extract more oil than n-hexane and Mixture 2. However, the utilization of the solvent is dependent on the end product from the residual palm oil.     

Optimization of biodiesel production from the waste cooking oil using response surface methodology

In this research, transesterification of the waste cooking oil has been studied. Response surface methodology (RSM) based on Box–Behnken design was used to investigate the effects of the main operating parameters, including the methanol to oil molar ratio, catalyst concentration, and reaction temperature, on the biodiesel yield. The results revealed that the catalyst concentration is the most important parameter. The maximum biodiesel yield under the optimized conditions was 99.38 wt.%. Thermogravimetric analysis (TGA) was used for the determination of biodiesel conversion and the results were compared with that of gas chromatography (GC) analysis, showing a very small difference. Furthermore, an empirical quadratic equation has been presented to show the relation between biodiesel conversion and product viscosity.     

城市有机混合垃圾的蚯蚓堆制处理试验研究

为了探讨加速城市生活垃圾的堆制处理及其资源化利用的有效措施,以采自南京市水阁有机废弃物填埋场的垃圾为代表,加入秸秆或牛粪,调节m(C)/m(N)和水分含量,预堆制15 d后,接种赤子爱胜蚓(Eisenia foetida)进行室内堆制处理.结果表明:30%牛粪+70%新鲜有机混合垃圾处理(NH处理)和20%秸秆+80%新鲜有机混合垃圾堆制处理(JH处理)的赤子爱胜蚓总体生长良好.蚯蚓堆制处理显著降低了有机混合垃圾堆制残留物干重,其中NH处理减少得最多.蚯蚓的接种显著降低了新鲜有机混合垃圾(HL)、堆制腐熟有机混合垃圾(DL)和JH处理的有机碳和全氮质量,提高了NH处理的有机碳和全氮质量.研究表明:城市有机混合垃圾在加入牛粪的基础上接种蚯蚓,其堆制效果较好,是处理有机混合垃圾的有效措施.     

Disintegration of municipal waste activated sludge by simultaneous combination of acid and ultrasonic pretreatment

The individual and simultaneous effects of acid and ultrasonic pretreatment on the disintegration of municipal waste activated sludge (WAS) were investigated based on chemical properties of WAS. In the combination of acid and ultrasonic pretreatment methods (ultrasonic-acid pretreatment), lowering pH accelerated and enhanced the disintegration of waste biological sludge. Therefore, the same disintegration efficiency (obtained by ultrasonic pretreatment alone) was achieved by the combined pretreatment in shorter sonication times. Optimum pretreatment conditions were ultrasonic power density of 1.0 W/mL and pretreatment time of 10 min for ultrasonic pretreatment alone, and ultrasonic power density of 1.0 W/mL, pretreatment time of 10 min and initial sludge pH of 2.0 for the combined pretreatment. Sludge disintegration degrees were about 30% and 40% under these optimized conditions, respectively. Optimum sludge concentration was found to be 1.0% total solid (TS) content for the combined pretreatment. As a result, ultrasonic-acid pretreatment has been determined as a new and effective combined sludge pretreatment method to improve the sludge disintegration.     

利用爆炸冲击波作用促进污泥改性试验探索

为了提高污泥的脱水效率,需要对污泥进行预处理.探索了一种新的污泥预处理方法,即利用炸药爆炸产生的冲击波作用于污泥.通过小型试验发现,污泥颗粒粒径在爆炸冲击波的作用下变小,污泥的絮状胶体结构破坏,污泥颗粒由胶结紧密变为疏松,从而证明了爆炸冲击波促进污泥改性的可行性.     

Improving disintegration and acidification of waste activated sludge by combined alkaline and microwave pretreatment

The individual alkaline or microwave pretreatment has been proved to be effective in disintegration and acidification of waste activated sludge (WAS). In this study, the effects of combined alkaline and microwave pretreatment at different pH and specific energy input (Es) on WAS disintegration were investigated using response surface methodology (RSM). Combined pretreatment achieved disintegration degree (DD) of 65.87% at Es of 38,400 kJ/kg TS and pH 11.0. The ANOVA further demonstrated that pH showed more significant effect on DD than Es. Anaerobic batch experiment results showed that combined pretreatment not only significantly improved volatile fatty acids (VFAs) accumulation but also shortened the time for the highest VFAs accumulation. The maximal VFAs accumulation (1500 mg COD/L) obtained at Es of 28,800 kJ/kg TS and fermentation time of 72 h, which was about two times that of the treatment without microwave (850 mg COD/L) at 96 h. The analysis of VFAs composition showed that the VFAs mainly consisted of acetic and iso-valeric acids, accounting for 57.3–70.1% of total VFAs.     

化学强化沉淀污泥的除磷效果研究

取吸附-生物降解(AB)工艺A段沉淀池出水,利用投加硫酸铝(AS)和聚丙烯酰胺(PAM)化学强化后的沉淀污泥进行除磷实验,考察沉淀污泥除磷效果和化学强化对污泥沉降性能的影响.结果表明:化学强化的沉淀污泥对污水的11P和浊度有较好的去除效果,其去除率随As投药量的增加而提高;当泥水比为66.7%,PAM为0.05mg/L,AS投药量(以Al2O3计,下同)为15.1 mg/L时,对TP和浊度的去除率分别为75.0%和60.9%;AS投药量从0 mg/L增加至15.1mg/L,沉淀污泥对COD去除率维持在23%～40%,对氨氮无去除作用;同一投药量(As为7.5 mg/L,PAM为0.05 mg/L)下,TP去除率随泥水比增大而提高,氨氮质量浓度无明显变化;投加AS和PAM化学强化除磷,污泥沉降比和体积指数随AS投药量增加而降低,污泥沉降性能提高.