Lightweight properties and pore structure of foamed material made from sewage sludge ash

Pore structure significantly affects the lightweight characteristics and thermal performance of materials. Therefore, in this study, sewage sludge ash (SSA) was used to make lightweight materials. Physical and chemical properties, and how the mixing proportions affected the foaming behavior were investigated, including the lightweight characteristics and pore structure of the materials produced. The experiments showed that the minimum required cement amount was determined by the compressive strength of the sewage sludge ash foamed material (SSAFM), not its alkali content. The hydration of cement and SSA mainly generated pores with diameters of less than 0.1  μm, but cement added with metallic aluminum powder produced pores with diameters larger than 10  μm. The addition of SSA increased the volume of pores smaller than 10  μm. The thermal conductivity of SSAFM was between 0.084 and 0.102 W/m K. Therefore, SSA could be used as the lightweight filler and heat-insulating material.     

Acid solubilization of sewage sludge and ash constituents for possible recovery

Many of the trace elements and phosphorus in digested sewage sludges can be solubilized with acid at an average acid cost of $41 and $77 per ton of dry solids for H₂SO₄ and HCl, respectively ($46 and $86/metric ton). But an economic gain accrued by the recovery of metals and phosphates would be minimal since processing of the large volumes of dilute acid leachate would be expensive. Based on acid costs alone, sludge detoxification does not seem to be economically feasible, so the elimination of metal discharges at source seems to be the only practicable solution to reducing heavy metal levels in digested sludges.

Sulfuric acid can be used to non-selectively solubilize metals and phosphates from sludge incinerator ash for about $21 per ton of ash treated ($24/metric ton). In most instances, separation and recovery of the constituents in the leachate would be too costly to make profitable recycle possible. Optimization of incineration parameters such as temperature can be used to minimize the environmental impact of landfilling sludge incinerator ash.     

高掺量粉煤灰高强度砼路面砖的研制及应用

本文叙述以高达50%重量比粉煤灰替代水泥的高标号砼路面砖研制和生产中攻克难关获得成功过程.并对其经济效益作了分析.     

某污水处理厂消化池简体滑模施工

滑模施工，是现浇混凝土工程中机械化施工程度较高的工艺之一，结合某污水处理厂消化池筒体结构滑模施工实例，重点介绍了筒体结构滑模系统的构成、滑模施工工艺，质量控制及保证措施。工程实践表明，筒体滑模施工取得了良好的施工效果和显著的经济效益，值得类似工程推广应用。     

砖瓦装备制造如何提高性能和质量(一)

分析了我国砖瓦装备行业的现状,从设计、结构、选材、制作等方面给出了真空挤出机整机和一些关键零部件的评判方法.提出改进行业技术标准,强化质量意识,走专业化道路来提高行业发展水平.     

城市污水厂污泥处置技术分析及福州市污泥处置的思考

本文对城市污水厂污泥处理处置主要技术进行分析,并阐述了国外污泥处置技术发展趋势,提出了污泥处理处置工作急需解决的问题。结合当前的污泥处置技术发展趋势,通过对福州市污水厂污泥处置现状及存在问题分析,提出了福州市今后的污泥处置技术路线:将厌氧消化做为有效减容、减量的手段,对污染物指标达到国家土地利用标准的污泥考虑土地利用,污染物指标不符合国家土地利用标准的污泥考虑焚烧和建材利用。     

Engineering and microstructure properties of contaminated marine sediments solidified by high content of incinerated sewage sludge ash

Management of incinerated sewage sludge ash(ISSA) and dredged contaminated marine sediments(CMSs) is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20% of sediment by mass) of ISSA in combination with cement/lime for solidification/stabilization(S/S) treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(～80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC) for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10% of lime and 20% of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(C-S-H)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.     

利用湖泊淤泥掺粉煤灰生产平瓦

介绍湖泊淤泥掺配粉煤灰平瓦生产过程中原料的处理、混合料的掺配与陈化、坯体成型与干燥、码窑与焙烧等工艺及操作技术.     

纳米SiO2改性及纳米SiO2聚氨酯密封胶的制备

为了改善纳米SiO2粒子的分散性,提高纳米SiO2在聚氨酯基体中的相容性,制备性能更佳的密封胶,利用甲苯二异氰酸酯(TDI)与纳米SiO2表面的羟基反应,缩合聚醚,在纳米SiO2粒子表面接枝上长链有机物,并用原位聚合法制得纳米SiO2/聚氨酯密封胶.分散性研究表明,改性后的纳米粒子在有机溶剂中能够很好分散.采用原位聚合法制备的纳米SiO2/聚氨酯密封胶的伸长率、拉伸强度、邵氏硬度有明显提高,能同时达到增强增韧的效果.当纳米SiO2添加量在5%左右时密封胶的综合性能较佳.     

Geotechnical and hydrochemical properties of sewage sludge

The geotechnical and geochemical properties of sewage sludge from Kaunas city, Lithuania, were investigated to assess whether it could form a low permeability landfill cover. New sludge, sludge stored or kept in the atmosphere and old sludge were studied. It was found that over time the strength of the sewage sludge increased due to self-consolidation and destruction of organic material. The concentration of metals in the sewage extract was considerably lower than in the landfill leachate. It was concluded that if kept in an open polygon for 1–2 years, the sewage sludge can be used as a low permeability landfill cover.     

Utilization of bagasse ash as a pozzolanic material in concrete

The physical properties of concrete containing ground bagasse ash (BA) including compressive strength, water permeability, and heat evolution, were investigated. Bagasse ash from a sugar factory was ground using a ball mill until the particles retained on a No. 325 sieve were less than 5wt%. They were then used as a replacement for Type I Portland cement at 10, 20, and 30wt% of binder. The water to binder (W/B) ratio and binder content of the concrete were held constant at 0.50 and 350 kg/m³, respectively.The results showed that, at the age of 28 days, the concrete samples containing 10–30% ground bagasse ash by weight of binder had greater compressive strengths than the control concrete (concrete without ground bagasse ash), while the water permeability was lower than the control concrete. Concrete containing 20% ground bagasse ash had the highest compressive strength at 113% of the control concrete. The water permeability of concrete decreased as the fractional replacement of ground bagasse ash was increased. For the heat evolution, the maximum temperature rise of concrete containing ground bagasse ash was lower than the control concrete. It was also found that the maximum temperature rise of the concrete was reduced 13, 23, and 33% as compared with the control concrete when the cement was replaced by ground bagasse ash at 10, 20, and 30wt% of binder, respectively. The results indicate that ground bagasse ash can be used as a pozzolanic material in concrete with an acceptable strength, lower heat evolution, and reduced water permeability with respect to the control concrete.     

Heavy metal and micronutrient uptake in soybeans as influenced by sewage sludge amendment

Soybean (Glycine max (L.) Merr.) uptake of the elements, Cd, Ni, Pb, Cu, Zn and Mn, from a sewage sludge-amended Mecklenburg soil was conducted in the greenhouse. “Bragg” soybeans were grown in pots for five weeks at which time the tops and roots were sampled separately for elemental analysis. Soil samples from each pot were extracted with DTPA (diethylenetriaminepentaacetic acid) and the concentration of extractable elements correlated with the elemental content in the soybean plant. There was a significant increase in dry matter production with sludge treatment. Concentrations of Cd, Ni and Pb in the soybean shoots and roots increased from sludge-amended soil as compared to the control. The metal concentration in the soybean tissue increased with increasing levels of sludge amendment. Uptake of the heavy metals was greater by the roots than by the shoots indicating some barrier to movement of the metals from roots to shoots. The DTPA extractable Cd in sludge-amended soil increased significantly, and showed correlation to the soybean tissue metal concentrations. As for the micronutrients, Cu increased in the soybean shoot as the extractable Cu increased. There was no significant relationship between soybean tissue Zn and Mn and extractable Zn and Mn.     

粉煤灰粘土平瓦干燥裂纹的成因及防治

介绍粉煤灰粘土平瓦在干燥过程中产生结构裂纹、机械性裂纹、风致裂纹、操作裂纹和翘曲变形的原因及消除方法。     

Use of TBM muck as construction material

Tunnel boring machines (TBMís) are widely used in tunnel construction in rock. The rock chips (muck) produced are rarely used for construction applications, however, because the suitability of the material is not well understood. Yet the cuttings appear to be of approximately the correct average size for some applications. If they are suitable in other respects, cost savings can be realized in tunnel construction, where aggregate is a common requirement. A review of standard construction aggregate specifications indicates that hardrock TBM much would be suitable for several construction applications with a minimum of processing: road pavement and structural concrete. Processing options also are discussed for cases where the raw TBM muck is nearly, but not quite, suitable. A 0.65 metric ton (1420 lb) cutting sample generated by a laboratory tunnel boring machine operating in a welded tuff is analyzed for suitability for different construction applications. In addition, numerous tunneling projects that use or have studied TBM waste for construction purposes are described.     

粉煤灰防水混凝土的配制及应用

介绍粉煤灰防水混凝土的配制和防水特性，粉煤灰防水混凝土抗渗性能好技术经济效果显著，和易性好，施工操作条件改善，工效提高，抗蚀性高，水化热低，可减少混凝土收缩与开裂，适用于地下构筑物及大体积防水工程。     

On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both

The advantages and drawbacks of existing wet chemical phosphorus (P) recovery technologies, their applicability to different types of sewage sludge ash (SSA) and the role of the decay products of detergent zeolites as a source of reactive Al in SSA are analyzed. Since neither a purely acidic nor a purely alkaline treatment are able to provide satisfactory technical solutions a wet chemical phosphorus (P) recovery process for sewage sludge ashes (SSAs) is investigated in detail that is based on a sequential treatment of SSA with an acid and a base. As a result of an acidic pre-treatment, the P fraction of the raw SSA that was bound as - alkaline-insoluble - calcium phosphate (Ca-P) is converted into aluminum phosphate (Al-P). This newly formed Al-P can be easily dissolved via alkaline treatment and then easily separated from the alkaline leachate via precipitation of Ca-P. The Al-component can be reused as precipitant for P-removal in waste water treatment plants (WWTPs). The investigated process requires fewer chemicals than the direct acidic dissolution of all P-compounds contained in the SSA. This is due to the described rearrangement of the P component from Ca-P to Al-P. That such a rearrangement of P occurs indeed was confirmed through a combination of XRD, ICP and XRF analyses together with mass balance calculations. The present investigation proves that the process works for very different types of SSAs: For Al-rich SSAs that come from WWTPs where Al-salt is used for chemical P-removal the described sequential treatment process works best and yields P-recovery rates as high as 70-77%. But even for SSAs from WWTPs where only iron salt is used for chemical P-removal, a considerable amount of the reactive Al necessary for the described P-rearrangement is supplied by decay products of detergent zeolites, a hidden Al-source present in most SSAs produced in Europe.     

外贴面砖的外墙外保温系统材料性能及施工要求探讨

对薄抹灰外墙外保温系统上直接粘贴面砖的问题进行了探讨,并就该系统粘贴面砖中采用相关材料的性能指标与施工工艺提出了调整建议。为保证该系统安全性与耐久性,采用外贴面砖的外墙外保温系统施工,宜用于多层建筑,且面砖质量不大于30kg/m2。     

Platinum-group elements in sewage sludge and incinerator ash in the United Kingdom: Assessment of PGE sources and mobility in cities

Platinum-group element (PGE) concentrations in sewage sludge and incinerator ash compared with average PGE concentrations in road dust show a common pattern, characterized by a negative Rh anomaly. This similarity, found at 9 UK incinerators, suggests that there is a universal characteristic PGE pattern produced by common processes of dispersal of Pt, Pd and Rh derived from automobile catalytic converters.Ninety-one sewage sludge and incinerator ash samples from the sewage treatment facilities in Sheffield, Birmingham and 7 other UK cities were analyzed for PGE. The highest concentrations are 602 ppb Pt and 710 ppb Pd with lower maximum concentrations of 65 ppb Rh, 100 ppb Ru, 33 ppb Ir and 12 ppb Os. Ash from incinerated sewage was found to have higher PGE concentrations compared to the original sludge and the PGE ratios are preserved during incineration.Rh is more mobilized and dispersed than the other PGE as it is transported from roads into the drainage system and into sewage. Pt/Pd ratios of 1.0 in road dust and 0.9 in sewage and incinerator ash suggest that Pd is more mobile than Pt during dispersal. PGE abundances in stored incinerator ash of varying ages appear to have been affected by the variation in use of Pt, Pd and Rh in catalytic converters due to variation in their market prices.Concentrations of Os, Ir and Ru in ashes are greater in Sheffield and London than all the other city sites and may be derived from point industrial sources.     

湖泊淤泥拌粉煤灰生产平瓦的工艺管理

我国的湖泊、江河众多,储量丰富的淤泥是生产砖瓦的宝贵资源.如丰厚的洞庭湖淤泥,给湖南省的砖瓦生产提供了得天独厚的条件.多年来,洞庭湖区的大部分砖瓦企业都利用淤泥生产砖瓦,获得了良好的经济和社会效益.