The effects of heat-shock pretreatment conditions on dark hydrogen fermentation from glucose

The effects of heat-shock pretreatment conditions on the efficiency of dark hydrogen fermentation from glucose were investigated. Anaerobic sludge was pretreated at different temperatures of 70°C, 80°C, and 90°C for different time durations including 7.5, 15, 22.5, 30, 37.5, and 45 min. All pretreatments suppressed the methanogens and no detectable methane was produced after pretreatments. Pretreatments at 90°C led to the higher hydrogen contents than 70°C and 80°C. The pretreatment at 90°C for 37.5 min led to the highest biogas yield, hydrogen yield, and hydrogen production rate of 4.31?mol/mol-glucose, 3.15?mol/mol-glucose, and 70.2?mL/h.g-VS, respectively.     

Olive oil mill effluents as a feedstock for production of biodegradable polymers

The aim of the present paper was to study the feasibility of using olive oil mill effluents (OMEs) as a substrate in biodegradable polymer production. OMEs were anaerobically fermented to obtain volatile fatty acids (VFAs), which are the most highly used substrate for polyhydroxyalkanotes (PHAs) production. The anaerobic fermentation step was studied both without pretreatment and with different pretreatments (i.e., centrifugation, bentonite addition, and bentonite addition followed by centrifugation) and at various concentrations (28.5, 36.7 and 70.4 g CODL(-1)). During fermentation, VFA concentration was determined (7-16 g CODL(-1)) as well as the corresponding yield with respect to initial COD (22-44%). At all initial concentrations, centrifugation pretreatment (with or without previous addition of bentonite) significantly increased the final VFA concentration and yield, whereas the addition of bentonite alone had no influence. Moreover, centrifugation pretreatment led to a different acid distribution, which affected the hydroxyvalerate (HV) content within the obtained copolymer poly beta-(hydroxybutyrate-hydroxyvalerate) [P(HB-HV)]. OMEs were tested for PHA production by using a mixed culture from an aerobic SBR. Centrifuged OMEs, both with or without fermentation, were tested. PHAs were produced from both matrices, but with fermented OMEs PHA production was much higher, because of the higher VFA concentration. The initial specific rate of PHA production obtained with fermented OMEs was approximately 420 mg COD g COD(-1)h(-1) and the maximum HV content within the copolymer was about 11% (on a molar basis). The HV monomer was produced only until propionic acid remained present in the medium.     

Hydrogen and electricity production from a food processing wastewater using fermentation and microbial fuel cell technologies

Hydrogen can be produced from fermentation of sugars in wastewaters, but much of the organic matter remains in solution. We demonstrate here that hydrogen production from a food processing wastewater high in sugar can be linked to electricity generation using a microbial fuel cell (MFC) to achieve more effective wastewater treatment. Grab samples were taken from: plant effluent at two different times during the day (Effluents 1 and 2; 735+/-15 and 3250+/-90 mg-COD/L), an equalization tank (Lagoon; 1670+/-50mg-COD/L), and waste stream containing a high concentration of organic matter (Cereal; 8920+/-150 mg-COD/L). Hydrogen production from the Lagoon and effluent samples was low, with 64+/-16 mL of hydrogen per liter of wastewater (mL/L) for Effluent 1, 21+/-18 mL/L for Effluent 2, and 16+/-2 mL/L for the Lagoon sample. There was substantially greater hydrogen production using the Cereal wastewater (210+/-56 mL/L). Assuming a theoretical maximum yield of 4 mol of hydrogen per mol of glucose, hydrogen yields were 0.61-0.79 mol/mol for the Cereal wastewater, and ranged from 1 to 2.52 mol/mol for the other samples. This suggests a strategy for hydrogen recovery from wastewater based on targeting high-COD and high-sugar wastewaters, recognizing that sugar content alone is an insufficient predictor of hydrogen yields. Preliminary tests with the Cereal wastewater (diluted to 595 mg-COD/L) in a two-chambered MFC demonstrated a maximum of 81+/-7 mW/m(2) (normalized to the anode surface area), or 25+/-2 mA per liter of wastewater, and a final COD of <30 mg/L (95% removal). Using a one-chambered MFC and pre-fermented wastewater, the maximum power density was 371+/-10 mW/m(2) (53.5+/-1.4 mA per liter of wastewater). These results suggest that it is feasible to link biological hydrogen production and electricity producing using MFCs in order to achieve both wastewater treatment and bioenergy production.     

Acidification of mid- and high-strength dairy wastewaters

Batch and continuous experiments were conducted to study the influence of dairy wastewater strength (2-30g-COD/L) on acidification at pH 5.5 and 37 degrees C. Results of batch experiments showed that carbohydrate was preferentially acidified as compared to protein and lipid. Production of VFAs (mainly acetate, propionate and butyrate) and hydrogen corresponded to carbohydrate acidification, whereas production of alcohols (mainly ethanol, propanol and butanol), plus i-butyrate and higher molecular-weight VFAs, corresponded to protein acidification. In treating high-strength wastewaters (8-30 g-COD/ L), acetate, butyrate and P(H2) decreased after reaching their peak levels before leveling off. Results of continuous experiments with 12h of hydraulic retention showed that acidification decreased with the increase of wastewater COD, from 57.1% at 2 g-COD/L to 28.8% at 30 g-COD/L; among the constituents in dairy wastewater, 92-99% of carbohydrates, 59-85% of protein and 12-42% of lipid were acidified. High-strength wastewater favored production of hydrogen and alcohols, especially propanol and butanol. The biomass yield was 0.258g-VSS/g-COD.     

Factors affecting the fate of active proteins introduced in wastewater sludges: investigation with green fluorescent protein

Green fluorescent protein (GFP) was used as a reporter protein to investigate the interactions and fate of the active conformation of proteins in wastewater sludge. GFP was chosen because its fluorescence is dependent on the integrity of its native conformation. We identified factors that cause the loss of GFP fluorescence when this protein is introduced in aerobic or anaerobic sludge. In both systems, soluble polymers present in the liquid fraction caused an initial loss of fluorescence, but stabilized the remaining fluorescent GFP molecules. In aerobic sludge, interaction of GFP with the sludge solids initially caused an additional loss of fluorescence but the remaining fluorescence kept fairly constant over the following hours. In anaerobic sludge, on the contrary, interaction of GFP with the sludge solids caused a temperature dependent loss of fluorescence, probably related to the presence of precipitated ferrous sulfide. No direct relationship was found between sludge protease activity and loss of GFP fluorescence, suggesting that proteases are not the primary factor controlling the fate of the active form of proteins in wastewater sludges.     

Effect of waste activated sludge pretreatment methods to mitigate Gordonia foaming potential in anaerobic digestion

In this study, waste activated sludge obtained from two full‐scale treatment plants with foaming issues was pretreated with acid/alkali treatment, acid‐phase fermentation, thermal treatment, ultrasonic treatment and metal salt treatment to investigate their effect on foam mitigation. Waste activated sludge was characterized for foaming index prior and after each pretreatment method. Among all pretreatment methods investigated, acid/alkali treatment and acid phase fermentation showed highest reduction of 53% in foaming and in inactivation of Gordonia amarae filaments. Pretreatment methods that resulted in sharp decrease in the foaming index concurred with higher amounts of dead foam formers as confirmed using live/dead staining and the PMA‐qPCR technique. Pretreating with iron(III)chloride gave good foaming reductions with 54% decrease in foaming potential at a concentration of 260 mg/L but did not result in a decline of foam formers as confirmed by live/dead staining. Ultrasonic treatment did not prove effective in lowering the foaming index or killing the G. amarae filaments.     

Enhancement of mercury(II) sorption from water by coal through chemical pretreatment

Enhancement of mercury(II) sorption from water by bituminous coal through chemical pretreatment was explored in the laboratory using batch sorption tests and downflow column studies. Both intensity of sorption and equilibrium sorptive capacity were enhanced significantly following nitric acid and hydrogen peroxide oxidation. Sulfurization and manganese oxide impregnation also showed promise. The chemically pretreated coal sorbents exhibited mercury sorption to a level higher than that accomplished using active carbon. Nitric acid or hydrogen peroxide oxidized or sulfurized coal may well replace active carbon in polishing mercury-laden waste following sulfide precipitation or removing mercury during municipal water treatment.     

钢管制造业废液的处理方法研究

生产无缝钢管的过程中会产生多种有毒有害的废液,若不及时处理就直接排入污水处理厂,将严重影响其出水水质,进而对环境造成污染.基于此,提出利用乙炔废渣中的Ca(OH)<,2>,对其中的Na<,2>S废液、含酸废液、磷化锌废液、乳化废液、电镀废液等5种零星废液进行综合预处理,然后再排入污水处理厂进行二级处理,不仅实现了"以废治废",而且也保证了污水厂出水水质的稳定达标.     

矿化垃圾与碱性添加剂对餐厨垃圾发酵产氢的影响

研究了不同配比的矿化垃圾与碱性添加剂对餐厨垃圾发酵产氢的影响。试验结果表明，矿化垃圾主要起种子菌作用，此外其高孔隙率和高阳离子交换能力可提高传质效果；而碱性添加剂则能够抑制耗氢菌活性，缓冲体系的pH。在矿化垃圾与碱性添加剂的协同作用下，餐厨垃圾与污泥进行联合发酵产氢，获得最大的氢气浓度为41％，氢气产率为95．8mL／gVS；产氢体系进行的主要是丁酸型发酵，且氢气的产生量与VFA的产生量直接相关；水解反应生成的有机酸进一步发酵转化为气相的过程成为发酵产氢的限制性步骤，只有在矿化垃圾和碱性添加剂的协同作用下，微生物才可将产生的大量有机酸迅速向气相转化。     

Using filtrate of waste biosolids to effectively produce bio-hydrogen by anaerobic fermentation

Waste biosolids collected from sewage works is a biomass containing a vast amount of polysaccharides and proteins, and thus is considered a potential substrate for producing hydrogen using anaerobic fermentation. This work demonstrated, contrary to the common assumption, that the solids phase in waste activated biosolids presents extra nutrients for anaerobes; it in fact prohibits effective bio-hydrogen production. Using filtrate after removal of solids from biosolids produces more hydrogen than using the whole biosolids, with the former reaching a level an order of magnitude higher than the literature results.     

铁炭Fenton/SBR法处理硝基苯制药废水

为探寻硝基苯废水的适宜处理工艺，开展了铁炭Fentort／SBR工艺处理硝基苯制药废水的试验研究。结果表明，铁炭内电解结合Fenton氧化的预处理工艺可有效去除废水中的硝基苯类物质，并提高了废水的可生化性。当原水的pH值为2～3、H2O2投加量为500～600mg／L时，调节预处理出水pH值至7～8并经沉淀处理后，对COD和硝基苯类物质的总去除率分别可达47％和92％。后续混合废水经SBR工艺处理后出水水质能满足国家污水排放标准。     

The pitfalls of protein quantification in wastewater treatment studies

Proteins, as one of the principal components of organic matter in wastewater, require adequate quantification to determine their concentration in the different stages of wastewater treatment process. Recent studies have used the corrected Lowry Method for protein quantification arguing that this method can differentiate proteins from interfering humic substances. In this study, the classic Lowry Method, the corrected Lowry Method and a commercial assay kit were assessed for the protein quantification in the presence of humic acid.     

Application of ferrous hydrogen peroxide for treatment of DSD-acid manufacturing process wastewater

A pretreatment method for the biological treatment of wastewater from 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD-acid) manufacturing processes, a refractory dye intermediate wastewater, based on combined ferrous hydrogen peroxide oxidation and coagulation-flocculation, was developed. When the wastewater was treated with ferrous hydrogen peroxide oxidation ([Fe2+] = 2.7 mmol/L, [H2O2] = 0.21 mol/L) after a flocculation using an organic flocculant TS-1 at a dosage of 3 g/L, the overall COD and color removals were 64 and 62%, respectively. BOD5/COD value of the effluent was 0.3. Ferrous hydrogen peroxide oxidation treatment can reduce the solubility of organic molecules with sulfonic group and increase the efficiency of coagulation treatment. The COD and color removals were both more than 90% when FeCl3 was used as the coagulation (dosages of two-step coagulation were 0.031 and 0.012 mol/L respectively) after a ferrous hydrogen peroxide oxidation pretreatment at a H2O2 dosage of 0.06 mol/L.     

Hydrolysis of macromolecular components of primary and secondary wastewater sludge by thermal hydrolytic pretreatment

A laboratory simulation of the thermal hydrolytic pretreatment (THP) process was performed on wastewater sludge, as well as key macromolecular components: proteins, lipids, and polysaccharides. Hydrolysis temperatures from 130 to 220 °C were investigated. The objectives of this study were to determine how and over which temperature range THP specifically affects sludge components, and whether hydrolysis temperature can be used to minimize the previously reported drawbacks of THP such as high total ammonia nitrogen (TAN) loads and the production of highly-colored recalcitrant organics. In addition, the applicability of THP to primary sludge (PS) was investigated.The breakdown of proteins, lipids, and polysaccharides was determined to be temperature dependent, and both waste activated sludge (WAS) and PS responded similarly to THP apart from intrinsic differences in lipid and protein content. Pure carbohydrate solutions were not largely converted to mono- or dimeric reducing sugar units at temperatures below 220 °C, however significant caramelization of starch and production of dextrose and maltose was observed to occur at 220 °C. Volatile fatty acid production during thermal hydrolysis was largely attributed to the breakdown of unsaturated lipids, and long-chain fatty acid production was not significant in terms of previous reports of methanogenic inhibition. Ammonia was produced from protein during thermal hydrolysis, however solids loading rather than thermal hydrolysis temperature appeared to be a more meaningful control for ammonia levels in downstream anaerobic digestion.     

Effect of ultrasound pretreatment in mesophilic and thermophilic anaerobic digestion with emphasis on naphthalene and pyrene removal

In many anaerobic digestion processes for the treatment of the sludge produced in wastewater treatment plants, the hydrolysis of the organic matter has been identified as the rate limiting step. This study is focused on the effect of ultrasonic pretreatment of raw sewage sludge before being fed to the mesophilic and the thermophilic anaerobic digestion. From particle size reduction, COD disintegration degree and biodegradability test, 11,000kJ/kg TS was estimated as the optimal specific energy in ultrasonic pretreatment. Moreover, the use of pretreated sludge improved significantly the COD removal efficiency and biogas production in lab-scale anaerobic digesters when compared with the performance without pretreatment, specially under mesophilic conditions. During ultrasonic pretreatment, the diffusion of polycyclic aromatic hydrocarbons (PAH) compounds to the aqueous phase was stated by a reduction in the pretreated sludge micropollutants content. With sonication, naphthalene was better removed than without this pretreatment, particularly in the mesophilic digester. However, pyrene removal remained at same efficiency level with and without ultrasonic pretreatment.     

玻璃窑余热电站锅炉补给水处理工艺设计

余热发电通常规模小,锅炉补给水处理工艺系统和处理设备、规模有其自身特点.通过分析低参数余热发电锅炉的水质要求,结合现代锅炉补给水处理技术的发展,分析并选择适合玻璃窑低参数余热发电项目要求的锅炉补给水处理方式.     

Athermal microwave effects for enhancing digestibility of waste activated sludge

A bench scale industrial microwave (MW) unit equipped with fiber optic temperature and pressure controls within pressure sealed vessels successfully simulated conventional heating (CH, in water bath). By identical temporal heat temperature profiles for waste activated sludge (WAS) samples, evaluation of the athermal effects of MW irradiation on WAS floc disintegration and anaerobic digestion was achieved. In a pretreatment range of 50-96 degrees C, both MW and CH WAS samples resulted in similar particulate chemical oxygen demand (COD) and biopolymer (protein and polysaccharide) solubilization and there was no discernable MW athermal effect on the COD solubilization of WAS. However, biochemical methane potential (BMP) tests showed improved biogas production for MW samples over CH samples indicating that the MW athermal effect had a positive impact on the mesophilic anaerobic biodegradability of WAS. BMP tests also showed that despite mild inhibition in the first 7d, MW acclimated inoculum digesting pretreated (to 96 degrees C) WAS, produced 16+/-4% higher biogas compared to the control after 15 d of mesophilic batch digestion. However, initial acute inhibition was more severe for non-acclimated inoculum requiring recovery time that was two times longer with only 4+/-0% higher biogas production after 17d. Inoculum acclimation not only accelerated the production of biogas, but also increased the extent of the ultimate mesophilic biodegradation of MW irradiated WAS (after 15-27 d).     

Impact of microfiltration treatment of secondary wastewater effluent on biofouling of reverse osmosis membranes

The effects of microfiltration (MF) as pretreatment for reverse osmosis (RO) on biofouling of RO membranes were analyzed with secondary wastewater effluents. MF pretreatment reduced permeate flux decline two- to three-fold, while increasing salt rejection. Additionally, the oxygen uptake rate (OUR) in the biofouling layer of the RO membrane was higher for an RO system that received pretreated secondary wastewater effluent compared to a control RO system that received untreated secondary effluent, likely due to the removal of inert particulate/colloidal matter during MF. A higher cell viability in the RO biofilm was observed close to the membrane surface irrespective of pretreatment, which is consistent with the biofilm-enhanced concentration polarization effect. Bacterial 16S rRNA gene clone library analysis revealed dominant biofilm communities of Proteobacteria and Bacteroidetes under all conditions. The Cramer-von Mises test statistic showed that MF pretreatment did not significantly change the bacterial community structure of RO membrane biofilms, though it affected bacterial community structure of non-membrane-associated biofilms (collected from the feed tank wall). The finding that the biofilm community developed on the RO membrane was not influenced by MF pretreatment may imply that RO membranes select for a conserved biofilm community.     

千万吨炼油厂污水处理场受冲击分析及控制对策

本文对南方某千万吨炼油厂高浓度甲醇污水冲击污水处理场进行了总结,分析了污水处理场受冲击的主要原因是储运罐区在甲醇泵检修过程中,因管理不到位导致甲醇泄漏进入罐区的污水预处理站六,污水预处理站六把含有高浓度甲醇的污水,排入污水处理场及加氢型酸性水汽提装置,引起含油污水和加氢型净化水COD异常升高,最终进入污水处理场并造成冲击。经过全面系统排查,作者梳理了炼油厂需要重点管控的甲醇、环丁砜、MDEA等废水污染物及产生部位,这些物质溶于水会导致污水COD数据异常升高并不易被发现,提出了通过开展检维修作业风险识别、完善污水排放监测和报告制度、强化污水处理操作人员培训、对各股污水设置在线监测等源头控制对策,加强过程污水排放管控,避免类似情况再次发生,对其他炼油厂具有一定的借鉴意义。     

Evaluation of sample preparation techniques for algal bioassays

The chemical and biostimulatory properties of mesotrophic pond water and eutrophic feedlot runoff were examined after subsamples of each were separately subjected to standard membrane filtration and autoclaving pretreatments for bottle test bioassays. Correspondingly separate subsamples were exposed to ultraviolet light to determine its effectiveness as a possible pretreatment. All three pretreatments fulfilled the requirement of destroying or removing indigenous algae, but each technique substantially altered the water chemistry changing the bioassay results. Filtration removed phosphorus; autoclaving raised the pH value, precipitated salts, and eliminated dissolved carbon dioxide; and ultra-violet light oxidized organic and inorganic nitrogen compounds.