Conditioning of aluminium-based water treatment sludge with Fenton's reagent: effectiveness and optimising study to improve dewaterability

Alternative conditioning of aluminium-based drinking water treatment sludge using Fenton reagent (Fe2+/H2O2) was examined in this study. Focuses were placed on effectiveness and factors to affect such novel application of Fenton process. Experiments have demonstrated that considerable improvement of alum sludge dewaterability evaluated by capillary suction time (CST) can be obtained at the relative low concentrations of Fenton reagent. A Box-Behnken experimental design based on the response surface methodology was applied to evaluate the optimum of the influencing variables, i.e. iron concentration, hydrogen peroxide concentration and pH. The optimal values for Fe2+, H2O2, and pH are 21 mg g(-1)DS(-1)(dry solids), 105 mg g(-1)DS(-1) and 6, respectively, at which the CST reduction efficiency of 48+/-3% can be achieved, this agreed with that predicted by an established polynomial model in this study.     

Recycling EDTA solutions used to remediate metal-polluted soils

The objective of this research was to investigate the recycling of ethylenediamine-tetraacetic acid (EDTA) used for the removal of trace metals from contaminated soils. We successfully used Na2S combined with Ca(OH)2 to precipitate the trace metals allowing us to recycle the EDTA. The results of batch and column leaching experiments show that both Ca-EDTA and Na-EDTA are powerful chelating agents with a similar soil remediation potential. The major advantage of Ca-EDTA is the preservation of soil organic matter. We found that Na2S was capable of separating the metals Cd, Cu and Pb from EDTA; however, the precipitation of Zn required the addition of Ca(OH)2. After reusing the reclaimed EDTA seven times, over a 14-day period, EDTA reagent losses ranged from 19.5% to 23.5%. Successive washing cycles enhanced the removal of trace metals from contaminated soils. The metal sulfide precipitates contain high concentrations of metals and could potentially be recycled.     

游泳池中隐孢子虫卵囊替代物的去除

隐孢子虫是常见的球状寄生虫。接触含有隐孢子虫卵囊的水体可致隐孢子虫病,主要的临床表现为腹泻,严重者可致死。游泳池是主要的传播场所。采用容积为5 500 L的游泳池,进行隐孢子虫卵囊替代物的修复模拟实验,研究在游泳池条件下絮凝沙滤技术对直径为4.5μm隐孢子虫卵囊替代物的去除效果。实验结果表明,氯化铝剂量为0.1 mg/L,沙滤料高度为30 cm,内循环流速为11.5 L/min,对隐孢子虫卵囊替代物去除率在90%以上。该技术对浊度具有较好的处理效果,当进水浊度降低且接近于出水浊度时,系统进入稳定运行阶段,对虫卵囊替代物去除率可以达到96%。     

常温条件下CAST工艺亚硝酸型硝化的实现及特性

采用循环式活性污泥法(CAST)处理模拟生活污水,通过控制曝气量,使反应器中DO在0.13～0.74 mg/L之间,在常温下快速实现亚硝酸型硝化,然后增大曝气量使反应器内DO在0.7～3.36 mg/L之间,控制曝气时间1.5 h,考察系统内亚硝酸型硝化的维持情况。结果表明,14℃条件下,通过先控制低溶解氧浓度再控制曝...     

Assessment of natural sepiolite on cadmium stabilization, microbial communities, and enzyme activities in acidic soil

A pot trial was conducted to assess the efficiency of sepiolite-induced cadmium (Cd) immobilization in ultisoils. Under Cd concentrations of 1.25, 2.5, and 5 mg?kg^?1, the available Cd in the soil after the application of 1–10 % sepiolite decreased by a maximum of 44.4, 23.0, and 17.0 %, respectively, compared with no sepiolite treatments. The increase in the values of soil enzyme activities and microbial number proved that a certain metabolic recovery occurred after sepiolite treatment. The dry biomass of spinach (Spinacia oleracea) increased with increasing sepiolite concentration in the soil. However, the concentration (dry weight) of Cd in the spinach shoots decreased with the increase in sepiolite dose, with maximum reduction of 92.2, 90.0, and 84.9 %, respectively, compared with that of unamended soils. Under a Cd level of 1.25 mg?kg^?1, the Cd concentration in the edible parts of spinach at 1 % sepiolite amendment was lower than 0.2 mg?kg^?1 fresh weight, the maximum permissible concentration (MPC) of Cd in vegetable. Even at higher Cd concentrations (2.5 and 5 mg?kg^?1), safe spinach was produced when the sepiolite treatment was up to 5 %. The results showed that sepiolite-assisted remediation could potentially succeed on a field scale by decreasing Cd entry into the food chain.     

RuO_2-IrO_2/Ti阳极电催化降解偶氮染料甲基橙模拟废水

以自制Ti基Ru O2-Ir O2镀层形稳电极为阳极,采用电催化氧化处理偶氮染料甲基橙模拟废水。以硫酸钠为支持电解质,在自然p H条件下分别考察了电解时间、电极间距、电流密度和电解质浓度等因素对甲基橙去除率的影响,并分析其原因。实验结果表明,在自然p H、电极间距为1.0 cm、电流密度为30.0 m A/cm2、电解质硫酸钠浓度为20.0 g/L、电解1.0h,甲基橙去除率高达90.0%以上。因此,电催化氧化法作为一种高效、简便的染料废水处理技术,具有一定的应用潜力。     

粉末活性炭对三烯丙基异氰脲酸酯的吸附性能简

用静态吸附法考察粉末活性炭对水中三烯丙基异氰脲酸酯（CAIC）的吸附行为,采用单因素分析法对活性炭吸附化工废水中TAIC的工艺条件进行研究。实验结果表明,在TAIC模拟废水中,其TAIC初始浓度为800 mg/L,pH为7,在温度为298 K、转速为150 r/min的条件下,当活性炭的投加量达到4.4 g/L,吸附反应时间为50 min时,TAIC的去除效率最高为96.17%;对于实际废水,其TAIC初始浓度为1 500 mg/L,溶液pH为3,在温度为298 K、转速为150 r/min的条件下,当活性炭投加量达到10 g/L,吸附反应时间为2 h时,TAIC的去除效率最高为46.8%。这也是由于实际废水组分复杂,其他有机物存在一定的吸附竞争机制。     

西北地区沙尘暴引发的荒漠化问题

从西北地区继1993～1995年连续3a出现沙尘暴之后，1996年甘肃和内蒙古西部的阿盟等地再次遭到沙尘暴的袭击入手，分析了沙尘暴发生的原因，指出它归根结底是荒漠化的直接后果。概述了荒漠化的状况及危害，并分析了其成因。     

Photo-degradation organic dyes by Sb-based organic-inorganic hybrid ferroelectrics

The organic-inorganic hybrid halide compounds have emerged as one of the most promising photoelectric material for their superior optoelectronic properties and hold great prospects for renewable energy substitutes and environmental protection as photocatalysis. Here, we report the optical properties of the Sb-based organic-inorganic hybrid ferroelectric materials: pyridine-4-aminium tetrachloroantimonate ((C₅H₇N₂)SbCl₄, sample 1), piperidin-1-aminium tetrachloroantimonate ((C₅H₁₃N₂)SbCl₄, sample 2) and tris(trimethylammonium) nonachlorodiantimonate (((CH₃)₃NH)₃Sb₂Cl₉, sample 3), which are a kind of exploited efficient photocatalysts. Samples 2 and 3 exhibit distinct photoelectric respond, which are mainly ascribed to their minor narrow band-gap compared with sample 1. For the ferroelectrics, the intrinsic of spontaneous polarization of sample 3 at room temperature is favourable for the separation of photogenerated electrons and holes within the photorespond process. Moreover, sample 3 shows the highest efficiency of photo-decomposed Rhodamine B (90.2% within 80 min) and Methyl Orange (MO) (97.4% within 50 min), thanks to the photo-excited electrons and holes promoting the formation of oxidative radical species during the photo-redox progress. These findings prove that the development of a novel Sb-based organic-inorganic hybrid halide compounds with good stability in the degradation of organic dyes paves a way to designing new photocatalyst.     

甲苯降解菌的分离、鉴定及其对甲苯的降解特性

从重庆钢铁集团焦化厂脱酚池车间污泥中分离纯化得到一株能以甲苯为惟一碳源和能源的革兰氏阴性菌。根据生理生化实验结果、菌落特征、菌体形态,初步鉴定为假单孢菌属。菌株的最佳生长条件为：pH7、温度35℃、加入量100mL培养基中加入60μL甲苯、接种量5．0％。考察了菌株对甲苯的降解特性,在甲苯质量浓度为150mg/L时,比降解速率达到0．211h^-1。