改进型石灰混凝法去除城市污水二级出水中有机物的研究

将石灰混凝处理后的沉淀泥渣进行回流，对石灰混凝法进行改进，研究改进后的石灰混凝法对城市污水二级出水中有机物的去除效果。结果表明，活性泥渣回流有利于提高石灰混凝法对城市污水二级出水中有机物的去除。回流位置在石灰投加前、复合絮凝剂投加后，最佳回流量为新泥渣产生量的100％～200％，活性泥渣回流的最佳pH为11．0～11．5；活性泥渣中CaCO3、Mg(OH)2、Fe(OH)3等沉淀物以及有机高分子絮体均有助于提高其对有机物的去除效果，其中Mg(OH)2沉淀物起主导作用；含循环泥渣的活性污泥回流，对有机物的去除效果无明显影响。     

膜电解技术处理含氯及重金属的废酸

采用离子交换膜电解技术处理铜冶炼过程产生的含氯及重金属的废酸。考察了废酸处理工艺、电解温度、电解时间、电流密度和催化剂的添加等条件对处理效果的影响。实验结果表明：采用先沉淀重金属后脱氯的废酸处理工艺，氯离子和铜离子的去除效果均较好;当以钛盐为催化剂时，在电解温度为40 ℃、电解时间为2.0 h、电流密度为825 A/m²的最佳工艺条件下，处理后废酸中的氯离子质量浓度为0.22 g/L，氯离子去除率为98.59%，铜离子质量浓度为0.45 g/L，铜离子去除率为95.08%，其他重金属大部分也得到有效去除。净化后的废酸可回用至铜冶炼的生产过程中。     

利用农药含钾废渣制备氯化钾

利用热解及钙盐沉淀法对农药含钾废渣进行处理,制得高纯度的KCl.通过管式炉反应器对农药含钾废渣中有机物的去除进行了研究,探讨了升温速率、热解终温、终温保持时间及空气流量对热解过程的影响,并对钙盐沉淀法除氟过程的溶液pH及m(Ca2+)∶m(F-)进行了确定.实验结果表明:当升温速率为20℃/min、热解终温为600℃、终温保持时间为90 min、空气流量为3.0m3/min时,废渣中的有机物完全分解;钙盐沉淀法除氟的最佳条件为溶液pH 8,m(Ca2+)∶m(F-)=3.0,氟离子的去除率达到98％;最终得到KCl的产率为70.6％,产品纯度为98.2％,符合国家Ⅰ级优等品标准.     

耐盐活性污泥的驯化及对有机氯化物的降解性能

研究了高盐条件下的活性污泥驯化工艺，比较了驯化活性污泥与未经驯化活性污泥对废水中有机氯化物的去除效果。研究结果表明，经驯化后，活性污泥的理化指标发生了改变，对水中丙酮的去除率平均为68．3％，对二氯乙烷的去除率平均为83．0％，均优于未经驯化的活性污泥。这说明在合适的条件下，活性污泥经过耐盐驯化后可提高微生物对水中含氯有机物的适应能力，提高含氯有机物的去除效果。     

干式还原法处理铬渣的机理及应用

采用干式还原法处理铬渣。在多级还原焙烧炉中于高温条件下，将过量的煤粉和铬渣混合后与O₂反应，经冷却、擦磨、磁分离后可得到铁精砂和处理后铬渣。介绍了干式还原法处理铬渣的机理和工艺参数。以3种铬渣试样进行应用试验，经多级还原焙烧—磁分离后，铬渣中的Cr（Ⅵ）质量浓度为0.05~0.18 mg/L，低于HJ/T301—2007标准中的要求（0.50 mg/L），可作为建材原料加以利用。磁分离得到的铁精砂产品中铁的质量分数大于50%，铁回收率大于70%。目前设计的多级还原焙烧炉单炉处理铬渣能力为150 kt/a，标煤消耗为35 kg/t，处理成本约为60元/t。     

NaOH强化催化湿式氧化处理制药污泥

采用NaOH强化催化湿式氧化的方法处理制药污泥,考察了各工艺条件对污泥VSS去除率和COD去除率的影响。实验结果表明,在NaOH加入量10 g/L、反应温度260 ℃、初始氧气压力1.0 MPa、反应时间60 min的最佳工艺条件下,污泥VSS去除率和 COD去除率分别达到95%和60%,VSS去除率较高,污泥减量化效果显著。NaOH强化催化湿式氧化反应处理制药污泥的机理是氢氧根在高温条件下促进了微生物细胞的水解,促使污泥固体组分分解转移到液相中,最终有机物被降解为小分子有机物、CO₂和水。     

臭氧氧化法处理染料废水研究

采用臭氧氧化法处理活性艳红K-2BP和分散兰2BLN染料水溶液,考察了反应时间、温度、pH等因素对处理效果的影响.结果表明pH对处理效果影响较大,碱性条件有利于有机物的矿化;活性染料较分散染料容易氧化;脱色率＞COD去除率＞TOC去除率.     

Ti/RuO2-IrO2-TiO2电极电解产生活性氯

采用电解法产生活性氯,降解废水中的有机物。考察了活性氯产生量的影响因素,并对Ti/RuO₂-IrO₂-TiO₂电极电解实际含氯废水的处理效果进行了研究。实验结果表明:通过增加Cl^-浓度和电流密度、减少SO₄^2-浓度和极板间距、降低电解温度的方法能够提高活性氯产生量,从而提高电极降解有机物的效果;对于Cl^-浓度为0.005 mol/L、COD为49 mg/L的废水,使用Ti/RuO₂-IrO₂-TiO₂电极,在极板间距为0.5 cm、电解温度为20 ℃、电流密度为20 mA/cm²、初始pH为8.0的条件下电解处理60 min,废水BOD₅/COD值由0.04提高到0.25,COD降至24 mg/L,达到DB 11/307—2013《水污染综合排放标准》中排入地表水体污染物B类排放限值(COD≤30 mg/L)的要求。     

连续流双室微生物燃料电池处理工业废水

以实际中药废水作为阳极基质、实际含镉废水作为阴极电解液,构建了连续流双室微生物燃料电池(MFC),考察了其产电性能及对两种废水的处理效果。78 d的运行数据表明:系统可实现最大输出电压417mV、最大体积功率密度11.8 W/m3,最大体积功率密度运行条件下的库伦效率为18.5%;在阳极进水有机物浓度变化较大的情况下,实现了阳极对中药废水中有机物的有效去除,平均COD去除率为81.5%;阴极对含镉废水中Cd2+的去除率为79.4%～84.8%。这表明MFC同步处理中药废水及重金属废水具有一定的可行性。     

电化学法处理高盐苯酚废水的研究

对在氯盐电解质中用电化学方法处理含酚废水进行了研究，着重探讨了盐的种类与浓度、反应温度与溶液：pH、电流密度、苯酚初始浓度及阴阳极转换频率对苯酚去除率的影响。在Na2SO4的浓度为0．2mol／L，NaCl的浓度为0．1mol／L、苯酚初始质量浓度为200mg／L、电流密度为0．04A／cm^2、温度为35℃、pH为12．5、阴阳极转换频率为5min/次及反应时间为200min的条件下，苯酚的去除率为99．5％，COD去除率为5％，CIO^-把苯酚氧化成了其他有机化合物。     

Biomass waste gasification - can be the two stage process suitable for tar reduction and power generation?

A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW_th. The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950 °C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar compound contents confirmed superiority of the two stage gasification system, drastic decrease of aromatic compounds with two and higher number of benzene rings by 1-2 orders. On the other hand the two stage gasification (with overall ER = 0.71) led to substantial reduction of gas heating value (LHV = 3.15 MJ/Nm³), elevation of gas volume and increase of nitrogen content in fuel gas. The increased temperature (>950 °C) at the entrance to the char bed caused also substantial decrease of ammonia content in fuel gas. The char with higher content of ash leaving the second stage presented only few mass% of the inlet biomass stream.     

Hydrogen-rich fuel gas production from refuse plastic fuel pyrolysis and steam gasification

In this study, experimental conditions were optimized to maximize the production of hydrogen gas from refuse plastic fuel (RPF) by pyrolysis and steam gasification processes conducted in a laboratory-scale reactor. We carried out gasification using 10-g RPF samples at different temperatures (700°-1000°C) with and without steam. The effect of the amount of steam (0–0.25 g/min) for RPF steam gasification was also studied. The effect of K₂CO₃ as a catalyst on these processes was also investigated. Experimental results showed that the hydrogen gas yield increased with temperature; with respect to the gas composition, the hydrogen content increased mainly at the expense of other gaseous compounds, which highlights the major extension of secondary cracking reactions in the gaseous fraction at higher temperatures.     

Reduction of tar using cheap catalysts during sewage sludge gasification

Solid-fuel conversion or gasification study of sewage sludge and energy recovery has become increasingly important because energy recovery and climate change are emerging issues. Various types of catalysts, such as dolomite, steel slag and calcium oxide, were tested for tar reduction during the sewage sludge gasification process. For the experiments on sewage sludge gasification reactions and tar reduction using the catalysts, a fixed bed of laboratory-scale experimental apparatus was set up. The reactor was made of quartz glass using an electric muffle furnace. The sewage sludge samples used had moisture contents less than 6%. The experimental conditions were as follows: sample weight was 20 g and reaction time was 10 min, gasification reaction temperature was from 600 to 800°C, and the equivalence ratio was 0.2. The quantity of catalysts was 2–6 g, and temperatures of catalyst layers were 500–700°C. As the reaction temperature increased up to 800°C, the yields of gaseous products and liquid products increased, whereas char and tar products decreased, showing effects on gas product compositions. These results were considered to be due to the increase of the water-gas reaction and Boudouard reaction. In the case of experiments with catalysts, dolomite (4 g), steel slag (6 g) and calcium oxide (6 g) were used. When the temperature of catalysts increased, the weight of the tar produced decreased with different cracking performances by different catalysts. Reforming reactions were considered to occur on the surface of dolomite, steel slag and calcium oxide, causing cracking of the hydrocarbon structure, which eventually showed reduced tar generation.     

半饱和褐煤活性焦预吸附—4级固定化生物滤池降解—褐煤活性焦吸附组合工艺处理超稠油废水

采用半饱和褐煤活性焦(HSLAC)预吸附—4级固定化生物滤池(I-BFs)降解—褐煤活性焦(LAC)吸附组合工艺处理超稠油废水。实验结果表明:组合工艺能达到出水COD≤50 mg/L的排放标准;4级I-BFs可完全去除有机酸、酯、呋喃类有机物,部分去除酚类物质,不能去除酰胺类物质,可将大分子有机物降解为小分子烷烃;I-BFs对疏水性有机碳和中性有机物有较高的去除率和去除量,较难去除腐殖质和腐殖质降解产物;4级I-BFs反应器内优势菌为类杆菌(Bacteroides sp.)、假单胞菌(Pseudomonas sp.)、异养反硝化菌(Thermomonassp.)、鞘脂单胞菌科(Sphingomonadaceae sp.)、鞘氨醇单胞菌(Sphingomonas sp.)和根瘤菌(Rhizobium sp.)。     

Gasification and smelting system using oxygen blowing for plastic waste including polyvinyl chloride

A new type of waste gasification and smelting system using oxygen blowing based on high-temperature metallurgy, was developed by Sumitomo Metals, Japan. This system can steadily gasify and melt not only municipal waste, but also plastic waste and polyvinyl chloride (PVC) waste by using a top-blow oxygen lance together with sideways-blow oxygen lances. As a result of gasification in the high-temperature reducing atmosphere and rapid gas cooling, dioxin-free, high-calorie purified gas was produced. Ash components in the wastes were smelted in a high-temperature reducing atmosphere, and high-quality slag free of heavy metals was produced. Most of the chlorine in the wastes was converted into hydrogen chloride in the off gas. The hydrogen chloride can be recovered as hydrochloric acid or chlorine, which are recyclable to PVC manufacturing.     

Modeling and comparative assessment of municipal solid waste gasification for energy production

Gasification is the thermochemical conversion of organic feedstocks mainly into combustible syngas (CO and H₂) along with other constituents. It has been widely used to convert coal into gaseous energy carriers but only has been recently looked at as a process for producing energy from biomass. This study explores the potential of gasification for energy production and treatment of municipal solid waste (MSW). It relies on adapting the theory governing the chemistry and kinetics of the gasification process to the use of MSW as a feedstock to the process. It also relies on an equilibrium kinetics and thermodynamics solver tool (Gasify®) in the process of modeling gasification of MSW. The effect of process temperature variation on gasifying MSW was explored and the results were compared to incineration as an alternative to gasification of MSW. Also, the assessment was performed comparatively for gasification of MSW in the United Arab Emirates, USA, and Thailand, presenting a spectrum of socioeconomic settings with varying MSW compositions in order to explore the effect of MSW composition variance on the products of gasification. All in all, this study provides an insight into the potential of gasification for the treatment of MSW and as a waste to energy alternative to incineration.     

Effect of sewage sludge content on gas quality and solid residues produced by cogasification in an updraft gasifier

In the present work, the gasification with air of dehydrated sewage sludge (SS) with 20wt.% moisture mixed with conventional woody biomass was investigated using a pilot fixed-bed updraft gasifier. Attention was focused on the effect of the SS content on the gasification performance and on the environmental impact of the process. The results showed that it is possible to co-gasify SS with wood pellets (WPs) in updraft fixed-bed gasification installations. However, at high content of sewage sludge the gasification process can become instable because of the very high ash content and low ash fusion temperatures of SS. At an equivalent ratio of 0.25, compared with wood pellets gasification, the addition of sewage sludge led to a reduction of gas yield in favor of an increase of condensate production with consequent cold gas efficiency decrease. Low concentrations of dioxins/furans and PAHs were measured in the gas produced by SS gasification, well below the limiting values for the exhaust gaseous emissions. NH(3), HCl and HF contents were very low because most of these compounds were retained in the wet scrubber systems. On the other hand, high H(2)S levels were measured due to high sulfur content of SS. Heavy metals supplied with the feedstocks were mostly retained in gasification solid residues. The leachability tests performed according to European regulations showed that metals leachability was within the limits for landfilling inert residues. On the other hand, sulfate and chloride releases were found to comply with the limits for non-hazardous residues.     

Influences of chlorine content on emission of HCl and organic compounds in waste incineration using fluidized beds

HCl and some organic compounds are the precursors of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in municipal solid waste incinerators. In this work, a lab-scale fluidized bed incinerator is adopted to study the relationship between the organic and the inorganic chlorine contents of artificial wastes and the emissions of HCl and organic compounds. The lower threshold limit (LTL) of chlorine content below which HCl and organic compounds are not generated is studied. Experimental results showed that organic chlorides had a greater potential to release chlorine than inorganic chlorides. The generation of organic pollutants fell, but the emissions of HCl increased with the temperature. The concentrations of chlorophenols (CPs)/chlorobenzenes (CBs) increased with chlorine contents. No LTL existed for HCl regardless of whether CaO was added. The LTL for CPs was between 0.1 and 0.3wt% of inorganic chloride, but there was none for organic sources. For CBs, the LTL was between 0.5 and 1.0wt% for inorganics at 700 and 800 degrees C, but 0.1-0.3 wt% at 700 degrees C and 0.3-0.5 wt% at 800 degrees C for organics. The production of PAHs and benzene, toluene, ethylbenzene and xylene (BTEX) was related to the surplus hydrogen ions that were not reacted with the chlorine. Adding CaO inhibited the production of HCl, CBs and CPs, but did not seriously affect PAHs and BTEX.     

Influence of mixed molten carbonate composition on hydrogen formation by steam gasification

Steam gasification in the presence of carbonate compounds is an effective method to recover useful materials from electronic waste streams by converting plastics into gaseous products that can be used for energy production and avoiding the expensive manual disassembly process. We investigated steam gasification of activated carbon in the presence of various mixtures of lithium carbonate, sodium carbonate, and potassium carbonate. The activated carbon was almost completely converted into hydrogen and carbon dioxide at 700°C under 0.1 MPa pressure in the presence of carbonate mixtures. Carbon dioxide was also derived from partial decomposition of lithium carbonate. Steam gasification was accelerated in the presence of various carbonate mixtures and at increasing steam partial pressures. These experimental results show that fluidity of carbonates, the potassium content of the carbonate, and the steam partial pressure are important factors in accelerating steam gasification.