Hydrolysis and acidification of activated sludge from a petroleum refinery

The cost-effective treatment of activated sludge that is generated by refining petroleum is a challenging industrial problem.In this study, semi-continuous stirred tank reactors(CSTRs) containing petroleum refinery excess activated sludge(PREAS)were used to comparatively investigate hydrolysis and acidification rates, after the addition of heneicosane(C_(21)H_(44))(R1)and 1-phenylnaphthalene(C16 H12)(R2) to different and individual reactors. Operation of the reactors using a sludge retention time(SRT) of 6 days and a pH of 5.0, resulted in the maintenance of stable biological activity as determined by soluble chemical oxygen demand(SCOD), volatile fatty acids(VFAs) production and oil removal efficiency. The optimum conditions for hydrogen production include a SRT of 8 days, at pH 6.5. Under these conditions, hydrogen production rates in the control containing only PREAS were 1567 mL/L(R0), compared with 1365 mL/L in Rl and 1454 mL/L-PREAS in R2.Coprothermobacter, Fervidobacterium, Caldisericum and Tepidiphilus were the dominant bacterial genera that have the potential to degrade petroleum compounds and generate VFAs. This study has shown that high concentrations of heneicosane and 1-phenylnaphthalene did not inhibit the hydrolytic acidification of PREAS.

Rapid aerobic granulation using biochar for the treatment of petroleum refinery wastewater

Aerobic granular sludge technology has great potential for the treatment of petroleum refinery wastewater.However,strategies to shorten the granulation time and improvement the stability still need to be developed.In this work,biochar was prepared from waste petroleum activated sludge(biochar-WPS) and used in a sequencing batch reactor for the treatment of petroleum refinery wastewater.Biochar-WPS presented the surface area of 229.77 m2/g,pore volume of 0.28 cm3/g,H/C and O/C atomic ratios of 0.42 and 0.21,respectively.The porous structure and a high degree of hydrophilicity were found to facilitate microbial colonization and adhesion as well as particle aggregation.Application of biochar-WPS resulted in the formation of more substantial and stable aerobic granules(~66% of granules> 0.46 mm diameter) 15 days earlier compared with the control.The addition of biochar-WPS enhanced the average removal efficiency of chemical organic demand(~3%),oil(~4%)and total nitrogen(~10%) over the control.Increased microbial richness and diversity were observed within the formed granules and had an increased(~4%) proportion of denitrifying bacteria.These results indicate that an aerobic granulation mechanism using biochar-WPS is a feasible option for the treatment of petroleum refinery wastewater.

MBBR工艺提升炼油废水生化处理能力的应用研究

利用流动床生物膜反应器(MBBR)对炼油厂废水处理传统老三套工艺"隔油-气浮-生化"的生化单元的传统活性污泥法(CAS)进行升级改造。以COD、氨氮和抗冲击能力为考核指标,考察了改造后的MBBR出水与CAS出水水质的不同。试验结果表明:与CAS相比,改造后的MBBR生化系统出水水质稳定,COD<60mg/L,氨氮<5mg/L;进水高浓度石油类和COD的冲击,对MBBR出水中的氨氮浓度影响较大,但是对出水COD浓度影响不大。

污泥陶粒催化剂的制备及其对炼油废水深度处理的研究

以粉煤灰、黏土和催化活性组分TiO2为原料,炼油废水生物处理过程中产生的剩余活性污泥为造孔剂,经造粒、高温焙烧制备出污泥陶粒催化剂,对催化剂的活性组分种类、活性组分和剩余活性污泥的添加量、焙烧温度进行了研究。结果表明,TiO2的催化活性优于CeO2、锰盐、铜盐和铁盐;以TiO2为活性组分的陶粒TiO2的最佳添加质量分数为6%;随着污泥添加量的增大,陶粒的催化活性逐渐增强,污泥添加量为20%时催化活性最好;最佳的焙烧温度为1100℃。最优条件下制备的污泥陶粒催化剂催化臭氧反应25min,即可将含盐炼油废水生化尾水中的COD从105.16mg/L降至45.31mg/L,达到新修订的国家排放标准。该催化剂重复使用活性无明显衰减,满足工业应用要求,具有良好的应用前景。

钢渣污泥陶粒催化剂的制备及其催化性能

以钢渣、粉煤灰、黏土、剩余活性污泥和过渡金属盐类为主要原料,经造粒、焙烧制备出钢渣污泥陶粒催化剂。研究了活性组分种类、原料添加量及焙烧温度对所制催化剂催化性能的影响,并借助羟基自由基捕获剂分析了其催化机理。结果表明,由锰盐与铜盐组合的活性组分具有明显协同催化作用;当钢渣和剩余活性污泥的添加量均为20%、锰盐与铜盐组成的活性组分添加量为6%、焙烧温度为1130℃时,所制陶粒催化剂催化性能最佳且活性稳定、使用寿命长。最优条件下制备的陶粒催化剂催化臭氧反应35 min,可将含盐炼油废水生化尾水的COD从103.51 mg/L降至47.03 mg/L,符合最新修订的国家排放标准;催化氧化过程遵循自由基反应机理。