钢渣预处理含铬废水及其废渣与铬渣的固化

用钢渣对含铬废水进行预处理，探讨了钢渣粒度、用量、废水pH值和添加硫酸亚铁还原剂的影响。结果表明，经硫酸亚铁还原处理后再用钢渣处理比单纯用钢渣处理的效果明显提高，采用钢渣／总铬质量比为40的100目钢渣处理经硫酸亚铁还原后的含铬废水，总铬和Cr^6＋去除率分别达79％和84％，采用钢渣柱进行的两级淋滤实验进一步表明该方法可作为工业上含铬废水处理的预处理段。处理后的废钢渣同工业铬渣一起进行水泥固化，标准养护20d后固化体表面Cr^6＋浸出率、破碎至5mm粒径以下和酸雨淋溶下的浸出液Cr^6＋浓度均符合安全标准，可作为普通建材或进行填埋处置。     

常温还原铁氧体法处理含铬废水

实验探究了常温还原铁氧体法处理含铬废水的最优工艺条件,研究了不同亚铁盐及氨氮和COD对处理效果的影响,对沉淀进行了化学分析与材料表征。实验表明,在n(Fe2+)∶n(Cr6+)=6,共沉淀pH=10.0,还原时间为2 min,共沉淀时间为15 min条件下,处理含铬废水可达最好效果,总铬浓度从1 600 mg/L降至1.5 mg/L以下,符合国家《污水综合排放标准》(GB 8978-1996)的要求,实现了常温条件下铁氧体法对含铬废水的处理。对于不同亚铁盐,氯化亚铁处理废水的性能要强于硫酸亚铁,沉降速率快且沉淀致密。一般浓度的氨氮(50 mg/L)与COD(500 mg/L)对处理效果没有明显影响。对沉淀进行酸稳定性分析和XRD表征,确定生成了稳定的含铬复合铁氧体。     

硫酸亚铁——粉煤灰法处理含铬电镀废水的试验

硫酸亚铁——粉煤灰法处理含铬电镀废水,Cr~(+6)去除率可以达到99%以上。对于 Cr~(+6)浓度小于50mg/l 的废水,经一次处理,就可以达到国家规定的排放标准;对于浓度较高的含铬废水,经两次处理后即可达到排放标准。与硫酸亚铁——石灰法比较,有以废治废、原料价格低廉和易于得到等优点。     

制革废水试验研究

采用预处理-混凝沉淀-微滤组合工艺对制革废水进行试验研究.结果表明,制革废水经预处理后用硫酸亚铁酸洗废液作混凝剂是行之有效的,经此工艺处理后,COD、BOD5、SS和色度去除率分别为80.4%、87.2%、88.6%和91.7%,处理后废水水质达到排放标准且可回用于生产.在较低温度下,用硫酸亚铁作混凝剂仍能较好地完成混凝沉淀,验证了硫酸亚铁的低温混凝效果.此工艺具有很好的应用前景,尤其适合北方寒冷地区.     

氧化-解胶联合法分离含铬铝型材污泥中的铬铝金属

以广东某铝型材厂产生的含铬铝型材污泥为研究对象,在不影响污泥含铝量的前提下,采用次氯酸钠氧化-硫酸钠解胶联合法单独分离污泥中的Cr(Ⅲ)。结果表明:通过次氯酸钠氧化Cr(Ⅲ)并浸出Cr(Ⅵ),在最佳条件下,铬浸出率为46.47%;然后水洗1次滤渣,去除残留的可溶性Cr(Ⅵ),再以硫酸钠为解胶剂去除被滤渣吸附的酸溶性Cr(Ⅵ),在最佳条件下,水洗-解胶除铬率为63.64%;经联合法处理后,污泥含铬量为0.80 mg·g-1,总除铬率为80.50%,含铝量损失率仅为1.08%。氧化后的含Cr(Ⅵ)废水经氯化钡处理后可在工艺中回用。利用联合法处理含铬铝型材污泥所需成本比HW17危险废物的处置费用低。     

柱生物曝气法吸附处理含铬废水

利用复合生物吸附剂FY01与活性污泥作为吸附材料,探讨了柱式生物曝气法对高浓度含铬电镀废水的生物吸附效果.研究结果表明,FY01性能稳定,耐进水pH冲击能力较强.当进水pH=2～5、流速为500 mL/h时,10 g FY01和5 g活性污泥联合处理60.4 mg/L含铬电镀废水2 h后,铬的去除率达78%以上;在4℃冰箱和23～28℃实验室保存50 d的FY01对铬的去除分别在78%～83%和77%～84%之间.柱式生物曝气吸附法对含铬废水的处理效果理想,运行稳定.串联处理2000 mL总Cr、Cu2 和COD浓度分别为60.4、4.51和48.2 mg/L的电镀废水2 h后,去除率分别高达92.1%、99.2%和71.4%.     

废铁屑-改性粉煤灰联用处理铬渣渗滤液

针对铬渣严重污染环境问题,以"以废治废"为研究目标,采用室内静态实验方法,进行废铁屑-改性粉煤灰联用处理铬渣渗滤液中Cr(Ⅵ)和总铬实验研究。实验结果表明,废铁屑与聚合氯化铝改性粉煤灰联用处理Cr(Ⅵ)和总铬效果优于单独采用其中一种物质;处理Cr(Ⅵ)浓度208 mg/L、总铬浓度260 mg/L的200 m L高浓度含铬废水最佳反应条件为:反应时间30 min,总投加量40 g,配比为1∶1,pH值4.1,对应Cr(Ⅵ)去除率99.93%,总铬去除率99.72%。处理后水质满足《污水综合排放标准》(GB 8978-1996)要求。     

Cr(Ⅵ)污染土壤的热解还原无害化处理

提出了用热解还原法对含铬土壤进行无害化处理的新技术,研究了热解温度、热解时间及土壤有机质对铬无害化处理的影响,分析了热解前后土壤中铬的元素形态的变化.同时还探讨了热解还原过程中Cr(Ⅵ)的无害化机制.结果表明,土壤中的有机质在热解还原过程中产生的挥发分对Cr(Ⅵ)的无害化起核心作用;在200～600℃范围内,Cr(Ⅵ)的还原量随着热解温度升高而增大,500.0℃最适合于经济有效地实现Cr(Ⅵ)的热解还原处理;Cr(Ⅵ)的热解还原过程较快.铬的形态分析结果表明,热解后可交换态和碳酸盐结合态铬量大大降低,大部分铬转化成了活性低的残渣态,极大地降低了铬的危害.     

微电解-生物法处理含铬电镀废水的研究

采用微电解生物法组合工艺处理含铬电镀废水,在实验过程中,电镀废水中的重金属离子通过微电解法预处理可去除90%以上,剩余部分被后续工艺的微生物功能菌去除。实验结果表明对Cr6+含量为50mg/L,Cu2+含量为15mg/L,Ni2+含量为10mg/L的废水,经处理后,重金属离子的净化率达999%,且无二次污染。     

硫系物对铬污染土壤的还原稳定化处理

采用化学还原技术,添加硫代硫酸钠、硫酸亚铁、连二亚硫酸钠、硫化钠处理某化工厂遗留地的铬污染土壤,考察了4种还原剂处理铬污染土壤的效果。结果表明:在养护时间为30d时,4种还原剂对土壤Cr(Ⅵ)的稳定效率均高于90%,其中采用硫代硫酸钠和硫酸亚铁的稳定效率分别为99.1%和96.8%;硫酸亚铁、硫代硫酸钠、连二亚硫酸钠和硫化钠对土壤Cr(Ⅵ)的还原效率分别为74.2%、64.1%、52.7%、49.2%;连二亚硫酸钠和硫化钠处理后土壤中铬有效态无明显变化,硫酸亚铁和硫代硫酸钠处理后土壤中铬有效态有所下降,占比(质量分数)从原土的27.4%降至14.0%、21.4%,残渣态从原土的23.4%分别增加至39.8%和39.7%,稳定性增强。在相同投加量下,硫酸亚铁是处理铬污染土壤效果最佳的还原剂。     

微波法处理含铬废渣的可行性分析

微波辐照解毒铬渣是一项新技术,为考察该技术应用的可行性,本文对铬渣解毒前后性状的变化进行了讨论。结果表明,该技术能较完全地使高价铬转化为低价铬,解毒渣中铬主要以三价形态存在,铬渣毒性得到消除;解毒渣浸出液中Cr6+浓度远低于国家危险废物鉴别标准,解毒渣已不属于危险固体废弃物,其在环境条件下可安全存放。说明该技术具有应用前景。     

饮用水源突发性铬污染去除方法的比较研究

通过对水源水中铬污染的不同去除方法的比较实验及验证实验,研究pH值、FeSO_4、NaHSO_3和活性炭的投加量对铬的去除效果的影响。实验结果表明,当原水中铬的含量为0.5 mg/L时,未调节pH值的条件下,亚硫酸氢钠与活性炭对铬的最高去除率为50%左右;硫酸亚铁还原沉淀在FeSO_4·7H_2O:Cr~(6+)投加比=16:1时,滤后出水中Cr~(6+)的去除率达到96.8%,中试出水中未检出Cr~(6+),出水的总Cr、总Fe等指标完全达到《生活饮用水卫生标准》(GB 5749-2006)的要求。     

利用钢渣对聚驱采油废水进行深度处理

利用钢渣对模拟聚驱采油废水进行深度处理，依靠吸附作用去除水中的HPAM。考察了钢渣粒径、搅拌速度、pH以及吸附时间对HPAM去除率的影响，进行了吸附等温线和吸附热力学分析，并对钢渣进行了吸附再生实验。当搅拌速度为250r／min，pH为2～10，吸附时间为90rain，钢渣粒径为10-16目、投加量为100g／100mL时，HPAM的去除率可达到84％以上。钢渣对HPAM的吸附符合Langmuir等温式，吸附自由能变和吸附焓的结果都表明，该吸附属于物理吸附。吸附之后的钢渣可以通过600℃焚烧得到再生，再生后仍可保持良好的吸附性能。     

BM二代菌去除电镀废水中重金属离子的效果研究

BM菌是一种能够高效去除电镀废水中重金属离子的新型功能菌群,实验研究了BM二代菌对Cr6+、Ni2+的最佳去除条件,结果表明:当水温为10~30℃,pH=2,Cr6+浓度为100 mg/L,反应10 min,菌废比为1∶200时废水中Cr6+的去除率达到98%以上;当水温为10~30℃,pH=8.5,Ni2+浓度为100 mg/L,反应10 min,菌废比为1∶200时废水中Ni2+的去除率达到96%以上;在相同条件下实际电镀废水中Cr6+和Ni2+的去除率均高于99%。     

废弃油基钻井液提取柴油剩余废弃物无害化处理研究

针对废弃油基钻井液中柴油回收过程产生的泥渣、废水、废白土和酸碱废渣具有高色度、高pH、高COD和高石油类的特点,通过优化实验得出了一步法无害化处理废弃混合物的最佳固化配方:水泥和粉煤灰加量分别为12.5%,激活剂SG加量1.5%,促凝剂LSL加量1.5%,石灰加量1%。在最佳固化配方下,固化体浸出液的各主要污染指标都符合《污水综合排放标准》(GB 8978-1996)一级标准,固化成本约100元/m3,与分别处理废渣、废液相比,其处理成本可降低约20%。     

Assessment of the mechanical stability and chemical leachability of immobilized electroplating waste

The effectiveness of cement based treatment technology, in immobilizing chromium laden electroplating sludge was assessed by conducting toxicity characteristic leaching procedure (TCLP). The mechanical stability of the blocks was tested by measuring the compressive strength. Other leaching tests such as NEN 7341 test, ANS 16.1 and multiple TCLP (MTCLP) test conducted on select solidified blocks showed that chromium was immobilized by the binder studied. A linear relationship was obtained between the cumulative fraction of chromium leached (CFL) and square root of time in the solidified samples proving that diffusion is the controlling mechanism for leaching of chromium. The leachability indices (LI) obtained for the solidified materials using cement and cement-fly ash system (EPC6, EPFC6A and EPFC6B) satisfy the guidance value as per US NRC, which clearly indicates that chromium is well retained within the solid matrix. Chromium concentrations in the TCLP leachates of the above mix ratios were well within the regulatory level of United States Environmental Protection Agency (USEPA). Molecular characterization of the solidified material was carried out using Fourier transformation infra red (FTIR) technique.     

Digested sewage sludge solidification by converter slag for landfill cover

A new technology for solidification of digested sewage sludge referred to as converter slag solidification (CSS) has been developed using converter slag as the solidifying agent and quick lime as the solidifying aid. The CSS technology was investigated by analyzing the physicochemical properties of solidified sludge and determining its microstructural characteristics. The feasibility of using solidified sludge as a landfill cover material was considered in the context of the economical recycling of waste. Sludge solidified using the CSS technology exhibited geotechnical properties that are appropriate for replacing currently used cover soil. Microscopic analyses using XRD, SEM and EDS revealed that the main hydrated product of solidification was CSH (CaO . SiO2 . nH2O), which may play an important role in the effective setting process. Negligible leaching of heavy metals from the solidified sludge was observed. The solidification process of the hydrated sludge, slag and quicklime eliminated the coliform bacteria. Recycled sewage sludge solidified using CCS technology could be used as an effective landfill cover.     

Remediation of Cr(VI) from chromium slag by biocementation

Here we demonstrate a calcifying ureolytic bacterium Bacillus sp. CS8 for the bioremediation of chromate (Cr(VI)) from chromium slag based on microbially induced calcite precipitation (MICP). A consolidated structure like bricks was prepared from chromium slags using bacterial cells, and five stage Cr(VI) sequential extraction was carried out to know their distribution pattern. Cr(VI) mobility was found to significantly be decreased in the exchangeable fraction of Cr slag and subsequently, the Cr(VI) concentration was markedly increased in carbonated fraction after bioremediation. It was found that such Cr slag bricks developed high compressive strength with low permeability. Further, leaching behavior of Cr(VI) in the Cr slag was studied by column tests and remarkable decrease in Cr(VI) concentration was noticed after bioremediation. Cr slags from columns were characterized by SEM–EDS confirming MICP process in bioremediation. The incorporation of Cr(VI) into the calcite surface forms a strong complex that leads to obstruction in Cr(VI) release into the environment. As China is facing chromium slag accidents at the regular time intervals, the technology discussed in the present study promises to provide effective and economical treatment of such sites across the country, however, it can be used globally.     

Advantages and risks of using steel slag in preparing composts from raw organic waste

It had been reported that iron and manganese oxides in steel slag enhanced the production of humic acid (HA) from low-molecular-weight compounds, such as phenolic acids, amino acids, and saccharides. In the present study, this function of steel slag was applied to the composting of raw organic wastes (ROWs). The degree of humification of HAs is an important factor in evaluating compost quality. Thus, HAs were extracted from the prepared composts and the humification parameters were determined, in terms of elemental compositions, acidic functional group contents, molecular weights, spectroscopic parameters from UV–vis absorption and ¹³C NMR spectra. The timing for adding steel slag affected the degree of humification of HAs in the composts. The weight average molecular weight of a HA when slag was added initially (29 kDa) was significantly higher than when slag was added after elevating the temperature of the compost pile (17–18 kDa). These results show that ROWs are decomposed to low-molecular-weight compounds after the pile temperature is elevated and the presence of slag enhances the polycondensation of these compounds to produce HAs with a higher degree of humification. Because the slag used in the present study contained several-tens ng g^?1 to several μg g^?1 of toxic elements (B, Cu, Cr, and Zn), leaching tests for these elements from the prepared composts were carried out. Levels for leaching boron from composts prepared by adding slag (0.2–0.4 mg L^?1) were obviously higher than the corresponding levels without slag (0.05 mg L^?1).     

镍渣的重金属浸出特性

在分析镍渣的矿物相组成和重金属元素含量的基础上,鉴定了镍渣样品的浸出毒性,并考察了pH、液固比和浸出时间等条件对镍渣样中铬、铅、铜和锌等重金属浸出特性的影响。结果表明,镍渣中的重金属总量约为渣样的0.9%,且铬、铜和锌的含量较高,需进行安全管理。实验所用镍渣样品为第Ⅰ类一般工业固体废物。在强酸条件下镍渣中重金属浸出浓度较大,pH3后浸出浓度显著降低;液固比40 L/kg时,镍渣中重金属不断溶出,液固比40 L/kg后,浸出达到饱和,浸出浓度趋于平衡;随着浸出时间的增加,重金属离子的浸出浓度先增加后减少,但由于各重金属性质不同,各重金属达到最大浸出浓度的时间不同。