Case study: Using soil washing/leaching for the removal of heavy metal at the twin cities army ammunition plant

COGNIS TERRAMET® soil leaching and Bescorp soil washing systems have been successfully combined to remediate an ammunition test burn area at the Twin Cities Army Ammunition Plant (TCAAP), New Brighton, Minnesota. This cleanup is the first in the country to successfully combine these two technologies, and it offers a permanent solution to heavy metal remediation. Over 20,000 tons of soil were treated in the project. The cleaned soil remained on-site, and the heavy metal contaminants were removed, recovered, and recycled. Eight heavy metals were removed from the contaminated soil achieving the very stringent cleanup criteria of <175 ppm for residual lead and achieving background concentrations for seven other project metals (antimony, cadmium, chromium, copper, mercury, nickel, and silver). Initial contaminant levels were measured as high as 86,000 ppm lead and 100,000 ppm copper, with average concentrations over 1,600 ppm each. In addition, both live and spent ordnance were removed in the soil treatment plant to meet the cleanup criteria. By combining soil washing and leaching, COGNIS and Bescorp were able to assemble a process which effectively treats all the soil fractions so that all soil material can be returned on-site, no wastewater is generated, and the heavy metals are recovered and recycled. No hazardous waste requiring landfill disposal was generated during the entire remedial operation.     

铬渣资源化处理的零排放工艺

采用氧化—还原法对某钢厂的粗铬渣进行提纯回收，对各项工艺参数进行了优化，探讨了铬渣零排放处理工艺的可行性。实验结果表明：在氧化温度80 ℃、氧化时间1.5 h、双氧水加入量2.35 mL/g（以铬渣计），还原时间15 min、还原pH 1.5、NaHSO₃加入量0.445 g/g（以铬渣计），沉淀pH 8.0，煅烧温度1 050 ℃、煅烧时间1 h的条件下，所得废渣的w（Cr）为1.29%，回收铬绿产品的w（Cr₂O₃）为97.20%，铬回收率为94.40%;处理后废水的ρ（总铬）约为0.06 mg/L，低于GB 13456—2012《钢铁工业水污染物排放标准》中规定的1.50 mg/L，既可作为循环用水，也可排放;处理后废渣中含大量硅元素，可作为生产水泥发泡节能砖或砌块的原料;整个回收过程清洁无污染，零排放，且具备一定的盈利空间。     

Aqueous leaching of cattle manure incineration ash to produce a phosphate enriched fertilizer

Ash produced from the combustion of livestock manure contains large amounts of phosphorus (P), which is an important resource as a fertilizer. Some studies have extracted and recovered P from incinerated biomass ash using inorganic acid or alkaline agents, which produce wastewater that requires treatment and is expensive due to the cost of chemicals. Livestock manure ash contains not only P, but also water soluble salts, which could be a negative influence on plant growth and shall be preferably removed from the recovered fertilizer. In this study, we removed salinity from cattle manure incineration ash by simple aqueous leaching, while retaining the P content. The optimal condition was a 20 min leaching time at a liquid/solid (L/S) ratio of 10 mL g-ash^?1. Under this condition, over 90 % of Cl and 20 % of Na in the original ash was removed, while over 99 % of the P was retained in the leached residue. The leached residue met the fertilizer standard in Japan in terms of citrate soluble fertilizer components and contained few heavy metals. X-ray analyses of the ash indicated that Cl was mainly present as KCl in the original ash, while P was mainly present as Ca compounds in the ash.     

The hygienic aspects of wastewater reuse

Historically drinking water contaminated with wastewater discharged from nearby communities has been a major public health problem whose solution was directed towards the treatment of drinking water rather than of the source of contamination. The increased need for deliberate wastewater reuse has stimulated greater interest in the ability of wastewater treatment processes to produce a product in which the risk of infection, upon reuse, is reduced to an acceptable level. A brief overview of the disease agents involved, human dose-response considerations, microbial standards, and treatment plant reliability is presented. Selected experiences with the question as to how our terrestrial experience can be applicable to advanced life support systems is addressed.     

钼酸铵的清洁生产工艺

以酸-盐预处理-离子交换组合工艺替代传统工艺,提出了氧化钼、氨生产钼酸铵清洁生产工艺.该工艺采用液、渣双循环代替液单循环,以电锅炉替换燃煤锅炉.含氨废气采用酸性生产废水吸收,产生的高浓度含氨废液进行汽提处理,分离出的氨回用于生产,废液和含氨废气处理后均达标排放,基本实现了钼酸铵的清洁生产.采用该清洁生产工艺生产钼酸铵,...     

Thermodynamic analysis of the energy recovery from the aerobic bioconversion of solid urban waste organic fraction

Waste management is of the utmost importance for many countries and especially for highly developed ones due to its implications on society. In particular, proper treatment before disposal of the solid urban waste organic fraction is one of the main issues that is addressed in waste management. In fact, the organic fraction is particularly reactive and if disposed in sanitary landfills without previous adequate treatment, a large amount of dangerous and polluting gaseous, liquid and solid substances can be produced. Some waste treatment processes can also present an opportunity to produce other by-products like energy, recycled materials and other products with both economic and environmental benefits. In this paper, the aerobic treatment of the organic fraction of solid urban waste, performed in a biocell plant with the possibility of recovering heat for civil or industrial needs, was examined from the thermodynamic point of view. A theoretical model was proposed both for the biological process of the organic fraction, as well as for the heat recovery system. The most significant results are represented and discussed.     

Optimization of compost fermentation of glycerol by-product discharged from biodiesel fuel production process

Development of a cheap system for reuse of glycerol by-product discharged from the biodiesel fuel (BDF) production process is needed in parallel with development of a low-cost BDF production system. In this article, optimization of compost fermentation of glycerol by-product was studied. The type and amount of additive nitrogen source was studied, and good utilization of glycerol was observed when 0.5 g of urea was added to a mixture of 625 g dry sawdust, 25 g of microbial seed, and 50 g of glycerol by-product. To achieve efficient compost fermentation, repeated batch fermentation was applied and five batch cultures were repeated. Although the pH level and nitrogen and water contents were maintained at suitable levels for microbial growth, the glycerol consumption rate gradually decreased with accumulation of oily compounds in the compost. Finally, a material cost evaluation of the compost fermentation proposed in this study was performed. The total material cost decreased to ￥0.57 /l of BDF when employing an existing compost system for the fermentation process, although sawdust used for mushroom cultivation was used in this study at the very high cost of ￥123 /kg dry sawdust. However, the cost of disposal of the glycerol byproduct as an industrial waste was ￥5.2 /l of BDF produced; therefore, there might be an economical advantage to compost fermentation of glycerol by-product from BDF production.     

Papermill industrial waste as a sustainable source for high efficiency absorbent production

Papermill sludge (PMS) is generated during the wastewater treatment process of paper production. Its handling and disposal techniques are of great concern for the environment. It can be landfilled as a waste, or it can be recycled and converted into useful products of high value. It has a very promising application as an absorbing agent for the cleaning of water surfaces polluted with hydrophobic substances (vegetable, synthetic and mineral oils, animal fats, fuels, organic chemicals and even coal dust). Here, we present the pretreatment procedure (hydrophobation, mechanical and thermal treatments) of PMS that produces a lightweight absorbent material (HAWSC - high efficiency absorbent for water surface cleaning), which floats on the water surface and binds hydrophobic pollutants with considerably higher efficiency than commercially available mineral and synthetic absorbents. After its application, it can be incinerated, due to its high caloric value, to produce energy. The incineration residues can then be formed into granules that can be used as an efficient absorbent for fluids spilled onto solid surfaces.     

Influence of the recycled material percentage on the rheological behaviour of HDPE for injection moulding process

The amount of polymer material wasted during thermoplastic injection moulding is very high. It comes from both the feed system of the part, and parts necessary to set up the mould, as well as the scrap generated along the process due to quality problems. The residues are managed through polymer recycling that allows reuse of the materials in the manufacturing injection process. Recycling mills convert the parts into small pieces that are used as feed material for injection, by mixing the recycled feedstock in different percentages with raw material. This mixture of both raw and recycled material modifies material properties according to the percentage of recycled material introduced. Some of the properties affected by this modification are those related to rheologic behaviour, which strongly conditions the future injection moulding process. This paper analyzes the rheologic behaviour of material with different percentages of recycled material by means of a capillary rheometer, and evaluates the influence of the corresponding viscosity curves obtained on the injection moulding process, where small variations of parameters related to rheological behaviour, such as pressure or clamping force, can be critical to the viability and cost of the parts manufactured by injection moulding.     

Using Chitosan as a Coagulant in Recovery of Organic Matters from the Mash and Lauter Wastewater of Brewery

Chitosan is a natural biopolymer which can be used to replace aluminum salts and chemical polymers as a coagulant to avoid the human health problems caused by the residual of aluminum and chemical polymers in water. Chitin is a major component in shrimp and crab shells, and chitosan can be produced from chitin via a deacetylated process. Since the biodegradation of chitin is very slow, large amount of discards from the processing of crustaceans has become a major concern in seafood industry. Therefore, more works are need to find the possible applications of chitin, chitosan and their derivatives. This research used chitosan as a coagulant to recover wheat dregs in the wastewater from washing the mash and the lauter unit in a brewery, and regards this study as an example to understand the influences of the characters of the wastewater on the treatment plant of brewery. The result shows that the␣wastewater from the mash and the lauter units can have the best treatment efficiency at the coagulant dosage of 120 mg/L in the original pH 4.5. Increasing the solution pH decreased the turbidity removal efficiency. The dominant mechanisms for chitosan to remove colloids in the␣wastewater are charge bridging and neutralization, and the later becomes less significant in␣the high pH. The coagulant of chitosan removed most of the colloidal form organic matter in the wastewater, but it has only little effect on the removal of dissolving organic matter. Chitosan is a natural material, after coagulation the sludge from the mash and lauter wastewater can serve directly as an animal husbandry fodder after been dehydrated. Therefore, the loading to wastewater treatment plant and the cost of treatment could be reduced.     

双掺粉煤灰再生骨料对混凝土强度影响研究

通过试验研究再生骨料混凝土中粉煤灰和再生骨料对混凝土强度的影响。采用粉煤灰替代部分水泥、再生骨料替代部分天然粗骨料的方法,通过正交试验测定混凝土立方体抗压强度的方法,来研究粉煤灰对再生骨料混凝土强度的影响。试验得出:当再生骨料掺量为20%~30%时,粉煤灰的最佳掺量为20%左右;当再生骨料掺量高于40%、粉煤灰掺量高于20%时,其混凝土拌合物搅拌时间不小于240 s,且当粉煤灰在20%~30%时,可获得较理想的混凝土抗压强度;当粉煤灰的掺入量分布在20%~30%、再生骨料的最佳掺量为50%时,可获得较理想的混凝土抗压强度。由此得出,合理的再生骨料、粉煤灰掺量对混凝土的抗压强度影响并不明显且有提高的趋势,对降低混凝土成本,提高建筑垃圾的再生利用,有一定的经济效益和社会效益。     

油脂工业废水的回用

以某油脂化工厂排放的达标废水为研究对象,提出了微絮凝-直接过滤、二级活性炭吸附、二氧化氯氧化消毒串连的深度处理工艺,并在小试基础上进行了油脂废水再生回用的工业化试验研究,处理规模为400m^3／d。处理后出水中COD、浊度、色度、阴离子表面活性剂（LAS）含量、细菌总数等均满足市政供水水质标准。回用水可作为碱化车间和油脂预处理车间的生产补充用水。     

Abiotic Hydrolysis of Some Poly-D-glucaramides and Subsequent Microbial Utilization/Degradation

Carbohydrate acid amides, diamides and polyamides have been proposed to be utilized as nitrogen plant fertilizers or fertilizer components, and experiments with Brassica rapa demonstrated a positive biological response when these compounds were used as the only source of fixed nitrogen for plant growth. The present study was carried out with the aim of elucidating the mechanism of degradation of these polymers in both soil/compost and in liquid media and the role of microorganisms in this process. The results obtained suggest that a major route of degradation of polyglucaramides in the environment is their abiotic hydrolysis/release of the diacid and diamine building block units of these polymers, which are then utilized for growth by microorganisms. In cell-free crude extracts from enrichment cultures obtained with different poly-D-glucaramides, no enzyme activities catalyzing the release of diamines from these compounds were detected.     

Phosphate fertilizer from sewage sludge ash (SSA)

Ashes from sewage sludge incineration are rich in phosphorus content, ranging between 4% and 9%. Due to the current methods of disposal used for these ashes, phosphorus, which is a valuable plant nutrient, is removed from biological cycling. This article proposes the possible three-stage processing of SSA, whereby more than 90% of phosphorus can be extracted to make an adequate phosphate fertilizer. SSA from two Swiss sewage sludge incinerators was used for laboratory investigations. In an initial step, SSA was leached with sulfuric acid using a liquid-to-solid ratio of 2. The leaching time and pH required for high phosphorus dissolution were determined. Inevitably, dissolution of heavy metals takes place that would contaminate the fertilizer. Thus in a second step, leach solution has to be purified by having the heavy metals removed. Both ion exchange using chelating resins and sulfide precipitation turned out to be suitable for removing critical Cu, Ni and Cd. Thirdly, phosphates were precipitated as calcium phosphates with lime water. The resulting phosphate sludge was dewatered, dried and ground to get a powdery fertilizer whose efficacy was demonstrated by plant tests in a greenhouse. By measuring the weight of plants after 6 weeks of growth, fertilized in part with conventional phosphate fertilizer, fertilizer made from SSA was proven to be equal in its plant uptake efficiency.     

旋流萃取分离技术处理石化电脱盐废水

采用旋流萃取分离技术处理某炼油厂常减压装置电脱盐废水(初始废水含油量约为5 000 mg/L),优化了废水除油的工艺条件。试验结果表明,废水除油的最佳工艺条件为:旋流萃取分离机中心转子的转速960 r/min、废水流量2 000 L/h、废水温度80℃。废水经旋流萃取分离后,废水的含油量小于200 mg/L,废水除油效果较好;分离后油相的含水量约为0.1%(w),盐质量浓度小于20 mg/L,可回注到常减压装置原料罐循环利用。对于2 Mt/a的常减压装置,采用旋流萃取分离技术后,每年可减少支出100.4万元。     

含铝酸性农药废水合成聚合硫酸铝混凝剂

采用农药三唑醇生产过程中产生的含铝酸性废水为原料,合成了聚合硫酸铝(PAS)液体混凝剂,并用于厂区污水站好氧池出水的混凝处理。考察了碱化剂用量、聚合温度、聚合时间等合成条件及PAS加入量、混凝pH等混凝条件对混凝效果的影响,并比较了PAS与商售聚合氯化铝(PAC)的混凝效果。实验结果表明:在n(碱化剂)∶n(硫酸铝)为2.1∶1、聚合温度为80℃、聚合时间为60 min的条件下,所得PAS液体混凝剂产品的w(Al2O3)为7.8%~9.0%,盐基度为45%~60%,pH为3.5~4.0,产量为0.75 t/t(以废水计);在PAS加入量为2.0 m L/L、混凝pH为10.0时,COD和SS的去除率则分别达到14.6%和83.0%;该PAS可替代厂区常规使用的商售PAC,日节约废水处理成本5 922元。     

Production of biologically safe digested manure for land application by a full-scale biogas plant with heat-inactivation

Inactivation of indigenous indicator micro-organisms such as faecal coliforms, coliphages, and faecal streptococci was investigated in a full-scale biogas plant that mainly digested cow manure. The biogas plant consisted principally of a feed reservoir, fermentation tank (37 degrees C), heat-inactivation process (70 degrees C), and five reservoirs for the heat-inactivated, digested manure that was used by a local livestock farmer as liquid fertilizer. Although all the indicators tended to exhibit stepwise decreases with each stage of treatment, coliphages were found to be more capable of surviving than faecal coliforms and faecal streptococci under mesophilic anaerobic conditions as well as high temperature conditions (heat-inactivation at 70 degrees C). Liquid fertilizer produced at the biogas plant had faecal coliform densities less than the stipulations of the US EPA 40 CFR 503 Class A limits. Heat-inactivation tests indicated that although coliphages exhibited more tolerance than other bacterial indicators between 37 and 70 degrees C, they were more sensitive to continuous temperature increase than faecal coliforms and faecal streptococci.     

喷淋工艺处理PVC塑料生产废气

采用喷淋工艺处理PVC塑料生产废气,将专利的吸收液与改型的喷淋塔相结合,在中试成功的基础上进行了实际工业化应用。应用结果表明:采用该工艺处理某PVC塑料生产企业的生产废气,吸收液在喷淋塔循环液中所占体积分数为15%时,废气中各污染物指标的去除率达85%以上,对于难处理的苯系物也能较好地去除;处理后废气中各污染物指标的含量满足GB 14554—1993《恶臭污染物排放标准》和DB 44/27—2001《大气污染物排放限值》的要求;该工艺装置运行费用较低,仅为电费和少量药剂费用,吸收液可循环使用,设备保养及维护简单,可满足市场需求。     

Assessment and analysis of industrial liquid waste and sludge disposal at unlined landfill sites in arid climate

Municipal solid waste disposal sites in arid countries such as Kuwait receive various types of waste materials like sewage sludge, chemical waste and other debris. Large amounts of leachate are expected to be generated due to the improper disposal of industrial wastewater, sewage sludge and chemical wastes with municipal solid waste at landfill sites even though the rainwater is scarce. Almost 95% of all solid waste generated in Kuwait during the last 10 years was dumped in five unlined landfills. The sites accepting liquid waste consist of old sand quarries that do not follow any specific engineering guidelines. With the current practice, contamination of the ground water table is possible due to the close location of the water table beneath the bottom of the waste disposal sites. This study determined the percentage of industrial liquid waste and sludge of the total waste dumped at the landfill sites, analyzed the chemical characteristics of liquid waste stream and contaminated water at disposal sites, and finally evaluated the possible risk posed by the continuous dumping of such wastes at the unlined landfills. Statistical analysis has been performed on the disposal and characterization of industrial wastewater and sludge at five active landfill sites. The chemical analysis shows that all the industrial wastes and sludge have high concentrations of COD, suspended solids, and heavy metals. Results show that from 1993 to 2000, 5.14+/-1.13 million t of total wastes were disposed per year in all active landfill sites in Kuwait. The share of industrial liquid and sludge waste was 1.85+/-0.19 million t representing 37.22+/-6.85% of total waste disposed in all landfill sites. Such wastes contribute to landfill leachate which pollutes groundwater and may enter the food chain causing adverse health effects. Lined evaporation ponds are suggested as an economical and safe solution for industrial wastewater and sludge disposal in the arid climate of Kuwait.     

燃煤电厂脱硫废水的零排放处理技术

采用化学沉淀—混凝—软化工艺对江苏某燃煤电厂湿法烟气脱硫废水进行物化法预处理,预处理后的废水再进行蒸发结晶,回收工业盐及冷凝水,最终实现了电厂脱硫废水的零排放。实验结果表明:在化学沉淀p H为9、混凝剂聚合硫酸铝铁(PAFS)加入量为2.5 m L/L、絮凝剂聚丙烯酰胺(PAM)加入量为2.0 m L/L的条件下,废水浊度可降至4.13 NTU,废水中的重金属、氟离子以及悬浮物被有效去除,预处理后废水的水质可达到GB8978—1996《污水综合排放标准》;蒸发结晶处理得到的工业盐和冷凝水分别符合GB/T 5462—2003《工业盐》的国家精制工业盐二级标准和GB 1576—2008《工业锅炉水质》的给水标准;脱硫废水的工业盐产率量为30 g/L。