污泥填埋场覆膜区悬索取泥施工技术

依托白龙港污水处理厂三期扩建工程,开展污泥填埋场覆膜区取泥施工技术研究。提出了覆膜区污泥悬索取泥技术,详述了覆膜开孔、装置入库、膜下清淤等悬索取泥关键施工工艺,并给出了揭膜清库、覆膜延长、臭气控制等配套工艺措施。悬索取泥施工技术的提出,实现了污泥填埋场覆膜区的膜下环保取泥,相关经验可供类似工程参考。

某大型污泥填埋场不揭膜取泥技术研究

污水厂污泥未实行规范填埋期间,大量的污水厂污泥倾倒在简易填埋场,随着时间推移,填埋场的稳定性和环境污染倍受关注,如何安全稳定异位处置填埋场污泥这已经成为新的环境问题.针对这种问题,采用清淤机器人膜下清淤的技术对污泥库中的污泥进行取泥中试试验,探讨清淤机器人膜下清淤的技术对填埋场污泥进行处理的可行性.研究结果表明:清淤机器人膜下清淤技术适用于填埋场污泥取泥工艺;填埋场污泥库区过大可采取分区域取泥;可采用中间缓冲池过渡提高出泥的稳定性;膜下取泥需进行多重除杂工艺便于输送及后续处置.清淤机器人膜下清淤的技术是填埋场污泥异位处置的有效途径之一,对于深层污泥的取泥技术要求还需进一步研究.

大型暂存污泥库区污泥绞吸出库技术应用研究

国内市政污泥因历史问题临时覆膜密闭堆放的问题屡见不鲜。某暂存污泥库区需要将污泥取出后进行干化处理后送至电厂焚烧,以解决环保问题,恢复暂存场地土地使用功能。取泥过程易发生臭气外泄,产生二次污染及作业安全问题。采用绞吸技术,可以在全封闭状态下完成污泥绞吸至污泥干化设备,通过牵引实现绞吸装置的膜下移动进行大部分污泥的绞吸出库。在绞吸完成后紧随进行清库作业,直至库区污泥全部取出。通过实践验证,绞吸出库相对常规挖泥工艺有快速、环保、出泥含水率受控等优势,可为类似项目提供参考。

浮船坞系船墩拆除施工技术

结合渤海石油浮船坞系船墩拆除工程实际,介绍钢管桩内部取泥、切割及拔除工艺要点和措施,并通过调整相关规范中的计算公式对钢管桩拔除力进行计算确定,为今后类似工程的施工提供借鉴。

Bioleaching of heavy metals from contaminated alkaline sediment by auto- and heterotrophic bacteria in stirred tank reactor

Bioleaching Xiangjiang River alkaline sediment contaminated by multiple heavy metals was investigated. Multiple metals in alkaline sediment possess significant toxicity to aquatic organisms or humans and will greatly inhibit bioleaching. The bioleaching method using autotrophic bacteria mixed with heterotrophic bacteria can solve this problem successfully. The experiment results showed that bioleaching efficiencies of Zn, Mn, Cu, and Cd were 95.2 %, 94.2 %, 90.1 %, and 84.4 %, respectively. Moreover, the changes of heavy metal concentrations in different fractions in contaminated sediment before and after bioleaching were analyzed by selective sequential extraction, and it was discovered that the main fractions of Zn, Mn, Cu and Cd after bioleaching are Fe-Mn oxide, organic associated form and a residual form. Its biotoxicity decreased greatly. The bioleaching heavy metals from sediment using autotrophic bacteria combined with heterotrophic bacteria can effectively improve the bioleaching efficiency and reduce toxicity.

Optimization of Extraction Conditions of Extracellular Polymeric Substances from Activated Sludge

[Objective] To explore the optimal extraction conditions of extracellular polymeric substances （EPS） from activated sludge. [Method] The efficiency of five methods （H2SO4, formaldehyde-NaOH, mixing, heating and NaOH） on the extraction of EPS was investigated comparatively. The optimal extraction conditions of the most suitable method were determined. [Result] NaOH method is most effective in extracting EPS with less DNA contamination and shortened extraction period. The optimal extraction condition was pH of 11, extraction time of 10 min and agitation speed of 80-120 r/min. [Conclusion] The determined optimal extraction condition provided theoretical basis for EPS study.

Extraction of Cadmium from Sewage Sludge Using Polyepoxysuccinic Acid

Polyepoxysuccinic acid （PESA）, as an environmental benign biodegradable chelant, was used to remove heavy metals from the sewage sludge of Shanghai Taopu Wastewater Treatment Plant. The extraction of cadmium （Cd） from sewage sludge using aqueous solution of PESA was studied. It was found that PESA was capable of extracting Cd from the sludge, and the extraction efficiency was dependent on both pH and the concentration of the chelating reagent. The extraction efficiency decreased gradually with increasing of pH, whereas the dependency on pH decreased as the concentration of PESA increased. In the case of the high PESA to total metal ratio, e.g., 10：1, the extraction efficiency reached above 70% within the pH range from 1 to 7. The highest extraction efficiency obtained in tbe experiment was 78%. By comparing the contents of the heavy metals in sewage sludge before and after the extraction, it was found that the extracted Cd came mainly from the four fractions： acid-soluble, reducible, oxidizable, and water-soluble fractions.

Selective extraction of gold(Ⅲ) from hydrochloric acid-chlorine gas leach solutions of copper anode slime by tri-butyl phosphate(TBP)

The oxidative leaching causes to dissolve various impurities such as Fe, Cu, Pd, Se in copper anode slime. Organicextractant tri-butyl phosphate (TBP) was used to purify leach solution. Several parameters, such as TBP, HCl and chloride inorganicsalt concentrations were chosen in order to determine efficient state for impurities separation. Standard solvent extraction tests forextraction and separation of Au, Pd, Pt, Fe, Cu and Se were conducted with equal volume of aqueous and organic phases in batchexperiments. The effect of hydrochloric acid, organic phase and metals initial concentration were examined at ambient temperature. Itwas found that 0.25 mol/L TBP in the presence of 2.5 mol/L hydrochloric acid can cause high extraction of gold. Meanwhile, in theseconditions the extraction of other impurities is negligible. After extraction, pregnant organic phase was scrubbed by distilled waterand some impurities were removed. Finally, gold was stripped by sodium thiosulfate solution. The stripping solution does not haveany impurities. By adding H2SO4 to stripping solution containing Na2S2O2, SO2 gas is released and Au3+ ions could be reduced.

Inversion of river-bottom sediment parameters using mechanically sampled specimens and subbottom profiling data

The study of river dynamics requires knowledge of physical parameters, such as porosity, permeability, and wave propagation velocity, of river-bottom sediments. To do so, sediment properties are determined on mechanically sampled specimens and from subbottom profiling. However, mechanical sampling introduces disturbances that affect test results, with the exception of grain-size distribution. In this study, we perform inversion of acoustic data using the grain-size distribution of mechanically sampled specimens and the relation between porosity and permeability from the Kozeny-Carman equation as prior information. The wave reflection coefficient of the water-silt interface is extracted from the raw subbottom profile. Based on the effective density fluid model, we combine the Kozeny-Carman equation and the wave reflection coefficient. We use experimental data from two Yellow River reservoirs to obtain the wave velocity and density of multiple sections and their spatial variations, and find that the inversion and testing results are in good agreement.

Enhanced extraction of scandium and inhibiting of iron from acid leaching solution of red mud by D2EHPA and sodium chloride

D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl concentration(C_(NaCl)),pH value,reaction time,stirring speed and O/A were investigated to extract scandium and separate iron from the acid leaching solution.The extraction mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR)and thermodynamic theory.The single-stage extraction efficiency of scandium,iron andβ(Sc/Fe)were 99.1%,9.4%and 1061.2,respectively,with C_(NaCl) of 75 g/L and XP204 of 0.75 at solution pH value of 1.2 and stirring speed of 200 r/min for 6 min,in which a good separation effect of scandium and iron was obtained.The vibration absorption peak Sc─O was contributed to the extraction of scandium with P204.The complex[FeCln]^(3−n) existed in the solution with adding NaCl into the acid leaching solution.The value of n was higher and the valence state of the complex[FeCln]^(3−n) was lower with an increase of chloride concentration,which restricts the extraction efficiency of iron with P204.The extraction of three stages in the counter-current simulation experiments was carried out according to the McCabe-Thiele diagram.Gibbs free energy change(ΔG)of−5.93 kJ/mol,enthalpy change(ΔH)of 23.45 kJ/mol and entropy change(ΔH)of 98.54 J/(mol·K)were obtained in the solvent extraction proces,which indicate that the extraction reaction is easily spontaneous and endothermic and a proper increase of temperature is conducive to the extraction of scandium.

Effect of Alkaline-Stabilised Sewage Sludge on Extractable Organic Carbon and Copper in Soils

An incubation experiment was conducted to evaluate the potential for water contamination with sludge-derived organic substances and copper following land application of alkaline-stabilised sewage sludge. Twocontrasting sludge-amended soils were studied. Both soils were previously treated with urban and ruralalkaline biosolids separately at sludge application rates of 0, 30 and 120 t ha-1 fresh product. The air-driedsoil/sludge mixtures were wetted with distilled water, maintained at 40 % of water-holding capacity andequilibrated for three weeks at 4 ℃ before extraction. Subsamples were extracted with either distilled wateror 0.5 mol L-1 K2SO4 solution. The concentrations of organic C in the aqueous and chemical extractswere determined directly with a total organic carbon (TOC) analyser. The concentrations of Cu in the twoextracts were also determined by atomic absorption spectrophotometry The relationship between the twoextractable organic C fractions was examined, together with that between extractable organic C concentrationand extractable Cu concentration. Application of alkaline biosolids increased the concentrations of soil mobileorganic substances and Cu. The results are discussed in terms of a possible increase in the potential forleaching of sludge-derived organics and Cu in the sludge-amended soils.

Zinc extraction from sewage sludge with [S,S]-EDDS

An environmentally friendly biodegradable chelant,[S,S]-ethylenediaminedisuccinic acid(EDDS),was used to separate heavy metals from sewage sludge based on chemical extraction technology.The extraction of zinc from sewage sludge with an aqueous solution of EDDS was studied under various conditions.It is found that the extraction efficiency of zinc using EDDS is equivalent to that using ethylenediaminetetraacetic acid(EDTA)at the molar ratio of chelant to total heavy metals of 1:1 over pH range of 5-9.EDDS is capable of extracting zinc from the sludge.The extraction efficiency is improved obviously and reaches a higher value within pH range from 3 to 10.The extraction efficiency maintains at about 65% when pH≥4.5 and the ratio of 10:1.By comparing the species contents of the zinc in sewage sludge before and after the extraction,it is found that the extracted zinc mainly comes from the acid soluble,reducible and oxidizable fractions.

Extraction DNA from Activated Sludge-Comparing with Soil Sample

DNA directly extraction from activated sludge and soil sample with enzyme lyses methods was investigated in this paper. DNA yield from activated sludge was 3.0 mg/g. MLSS, and 28.2 -43.8 μg/g soil respectively. The resulting DNA is suitable for PCR. By studied methods, higher quality and quantity of sludge DNA could be obtained rapidly and inexpensively from large number of samples, and the PCR product obtained from this protocol was not affected by contaminated higher concentration of heavy metals.

Optimization of the Extraction Process of Polysaccharides from Tegillarca granosa by Response Surface Methodology

[ Objective] The aim was to use response surface methodology to determine optimum conditions for extraction of polysaccharides from Tegillarca granosa. [ Method] Response surface methodology with three-factors and throe-levels was carried out for optimizing the extraction process of polysacchafides from Tegillarca granosa. A central composite des（gn including independent variables, such as extraction temperature （A）, extraction time （B）, and ethanol concentration （C） was obtained through Box-Benhnken central combination design. Selected response which evaluates the extraction process was polysacchadde yield. [ Result] The independent variable with the largest effect on response was ethanol concentration （C）. The optimum extraction conditions were found to be extraction temperature 69.6℃, extraction time 6.2 h, and ethanol concen- tration of 78% （V/V）, respectively. Under these conditions, the extraction efficiency of polysaccharide can increase to 1. 635%. [ Coaclusioa] Study on the extraction of polysaccharides from Tegillarca granosa could provide certain theoretical direction for extracting polysaccharides from Tegillarca granosa on a large scale.

In Vitro Biossay for Assessing Estrogenic Activity of Sewage Treatment Works

The estrogenic activity of influents and effluents of five municipal sewage treatment works （STWs） in Nanjing was investigated. The water samples were enriched by solid phase extraction, then eluted with different polar solvents, and f＇mally three fractionated extracts were obtained. Estrogen receptor recombinant yeast screen was used to evaluate the estrogenic activity of individual fractionated extracts and their mixture. The results show that the influents and effluents of the two STWs mainly receiving industrial wastewater have no obvious estrogenic activity, and the water samples from the other three STWs mainly receiving domestic wastewater show different degrees of estrogenic activity. The total estrogenic concentration ranged from 171. 52 ng/L EEQ （E2 - equivalent concentration） to 1 008.37 ng/L EEQ in the influents, and from ND （not detected） to 36.3 ng/L EEQ in the effluents. By comparing the results of different fractionated extracts, the methanol and dichloromethane extracts of the water samples show higher estrogenic activity, while the hexane extracts very low. The （xeno）estrogens from domestic wastewater could be removed obviously by activated sludge treatment units. However, the effluents of STWs in Nanjing still have chemical contaminants capable of binding to estrogen receptors.

Chromium Extraction from Sewage Sludge Using Polyepoxysuccinic Acid

An environmentally benign biodegradable chelant,polyepoxysuccinic acid(PESA),was used to separate heavy metals from sewage sludge from the Shanghai Taopu Wastewater Treatment Plant,China,based on chemical extraction technology.The extraction of chromium(Cr) from sewage sludge with an aqueous solution of PESA was studied under various conditions.It was found that the extraction of Cr using PESA was more efficient than that using ethylenediaminetetraacetic acid(EDTA) and S,S-ethylenediaminedisuccinic acid(EDDS) under similar conditions.PESA was capable of extracting Cr from the sewage sludge,and the extraction efficiency was obviously dependent on both the pH and the concentration of the chelating reagent.The extraction efficiency decreased gradually with increasing pH,and the dependence on pH decreased as the concentration of PESA increased.The extraction efficiency reached 58% under conditions of pH = 4 and a ratio of PESA to total heavy metals of 10:1.The extraction efficiency was maintained above 40% within the pH range from 1 to 7 at the high ratio of PESA to total heavy metals of 10:1.Comparing the contents of heavy metals in the sewage sludge before and after the extraction,it was found that the extracted Cr came mainly from the reducible and oxidizable fractions.