Applying the three R’s: Reduce,reuse, and recycle in the chemical industry

Pollution prevention (P2) assessment was conducted by applying the three R’s, reduce, reuse, and recycle, in a chemical industry for the purpose of reducing the amount of wastewater generated, reusing paint wastewater in the manufacture of cement bricks, recycling cooling water, and improving water usage efficiency. The results of this study showed that the annual wastewater flow generated from the paint manufacturing can be reduced from 1,100 m³ to 488.4 m³ (44.4% reduction) when a high-pressure hose is used. Two mixtures were prepared. The first mixture (A) contains cement, coarse aggregate, fine aggregate, Addicrete BVF, and clean water. The second mixture (B) contains the same components used in the first mixture, except that paint wastewater was used instead of the clean water. The prepared samples were tested for water absorption, toxicity, reactivity, compressive strength, ignitability, and corrosion. The tests results indicated that using paint wastewater in the manufacture of the cement bricks improved the mechanical properties of the bricks. The toxicity test results showed that the metals concentration in the bricks did not exceed the U.S. EPA limits. This company achieved the goal of zero liquid discharge (ZLD), especially after recycling 2,800 m³ of cooling water. The total annual saving could reach $42,570 with a payback period of 41 days.

Implications: This research focused on improving the water usage efficiency, reducing the quantity of wastewater generated, and potentially reusing wastewater in the manufacture of cement bricks. Reusing paint wastewater in the manufacture of the bricks prevents the hazardous pollutants in the wastewater (calcium carbonate, styrene acrylic resins, colored pigments, and titanium dioxide) from entering and polluting the surface water and the environment. We think that this paper will help to find the most efficient and cost-effective way to manage paint wastewater and conserve fresh water resources. We also believe that this paper provides a rich agenda for future research in water conservation and industrial wastewater reuse subjects.     

城市河涌受污染底泥的固化/稳定化处理

为了给河涌疏浚底泥的资源化提供技术支持,以广州市车陂涌表层受污染底泥为研究对象,用水泥、石灰、粉煤灰、膨润土等材料对底泥进行固化/稳定化处理实验。通过无侧限抗压强度、污染物在模拟自然条件下(中性)的释放特征、毒性浸出实验(酸性条件)对固化/稳定化处理效果进行综合分析。结果表明:经合适的处理后,固化体抗压强度能高于300 kPa;固化体自然条件下重金属的释放量明显减少,固化/稳定化处理能够有效减缓和减少固化体的二次污染;毒性浸出实验结果表明,河涌底泥经固化/稳定化处理后其重金属浸出能力显著降低。     

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.     

Strength development of solidified/stabilized organic waste and optimum treatment design

Artificially contaminated (spiked) natural soils were solidified/stabilized using various combinations of commonly used additives, such as lime, cement, fly ash, activated carbon, and silica fume. The effectiveness of the solidification/stabilization (S/S) processes was evaluated based on experimental findings from compaction testing, unconfined compressive shear strength, and X-ray diffraction (XRD). Correlations of limited reliability between unconfined compressive strength and penetrometer and torvane measurements were derived. Results from XRD experiments indicated that certain organic contaminants (i.e., naphthalene and pyrene) might impact the S/S processes for a given combination of additives. The type and amount of organic contaminants also affected the pozzolanic reactions. Specifically, the absence or small peak intensity of pozzolanic product XRD patterns for a given combination of additives was a good indication that the type and the amount of organic contaminant present inhibited pozzolanic reactions. This phenomenon was tested and confirmed for actual field-contaminated samples.     

Resource recycling through artificial lightweight aggregates from sewage sludge and derived ash using boric acid flux to lower co-melting temperature

This study focuses on artificial lightweight aggregates (ALWAs) formed from sewage sludge and ash at lowered co-melting temperatures using boric acid as the fluxing agent. The weight percentages of boric acid in the conditioned mixtures of sludge and ash were 13% and 22%, respectively. The ALWA derived from sewage sludge was synthesized under the following conditions: preheating at 400 °C 0.5 hr and a sintering temperature of 850 °C 1 hr. The analytical results of water adsorption, bulk density, apparent porosity, and compressive strength were 3.88%, 1.05 g/cm³, 3.93%, and 29.7 MPa, respectively. Scanning electron microscope (SEM) images of the ALWA show that the trends in water adsorption and apparent porosity were opposite to those of bulk density. This was due to the inner pores being sealed off by lower-melting-point material at the aggregates' surface. In the case of ash-derived aggregates, water adsorption, bulk density, apparent porosity, and compressive strength were 0.82%, 0.91 g/cm³, 0.82%, and 28.0 MPa, respectively. Both the sludge- and ash-derived aggregates meet the legal standards for ignition loss and soundness in Taiwan for construction or heat insulation materials.

Implications Artificial lightweight aggregates (ALWAs) could be synthesized from sewage sludge and derived ash. In this study, co-melting technology of low temperature was applied with boric acid as a fluxing agent and the formation temperature of glass phase was decreased to 900 °C. Both aggregates derived from sludge and ash meet regulatory standards of ignition loss and soundness in Taiwan for construction or heat insulation material.     

利用多年期赤泥和煤矸石制备烧结砖

以多年期赤泥和煤矸石为主要原料,分析了其化学成分和物性特征,通过设计不同的原料配比和烧结温度,探讨其最佳工艺条件以及各种参数指标,试图为赤泥的大宗化利用提供一种新的途径。实验结果表明最佳工艺条件为:多年期赤泥与煤矸石质量比为20∶80,成型压力为6 MPa,烧结温度为1 100℃左右保温2 h。烧结砖体"泛霜"现象基本消失,抗压强度为12.18 MPa、吸水率为21.6%,满足国家粉煤灰普通烧结砖GB5101-2003中的要求。     

Immobilization of antimony waste slag by applying geopolymerization and stabilization/solidification technologies

During the processing of antimony ore by pyrometallurgical methods, a considerable amount of slag is formed. This antimony waste slag is listed by the European Union as absolutely hazardous waste with a European Waste Catalogue code of 10 08 08. Since the levels of antimony and arsenic in the leachate of the antimony waste slag are generally higher than the landfilling limits, it is necessary to treat the slag before landfilling. In this study, stabilization/solidification and geopolymerization technologies were both applied in order to limit the leaching potential of antimony and arsenic. Different combinations of pastes by using Portland cement, fly ash, clay, gypsum, and blast furnace slag were prepared as stabilization/solidification or geopolymer matrixes. Sodium silicate–sodium hydroxide solution and sodium hydroxide solution at 8 M were used as activators for geopolymer samples. Efficiencies of the combinations were evaluated in terms of leaching and unconfined compressive strength. None of the geopolymer samples prepared with the activators yielded arsenic and antimony leaching below the regulatory limit at the same time, although they yielded high unconfined compressive strength levels. On the other hand, the stabilization/solidification samples prepared by using water showed low leaching results meeting the landfilling criteria. Use of gypsum as an additive was found to be successful in immobilizing the arsenic and antimony.

ImplicationsDespite the wide use of antimony for industrial purposes, disposal options for an antimony waste such as slag from thermal processing of antimony ore were not reported in the existing literature. This study aimed to develop a disposal strategy for the hazardous antimony waste slag. The findings of this study would contribute to understand the immobilization mechanisms of antimony and arsenic and will also be of interest to the owners of the antimony ore processing plants and to researchers investigating the efficiency of stabilization/solidification and geopolymerization technologies.     

浙江省建筑材料放射性水平及居民受照剂量估算

报道了１９８８年－１９９５年浙江省建筑材料中放射性水平和所致居民剂量的计算结果。采用高纯锗γ能谱法测定了该地区的６种,１３９个建筑材料样品中放射性核素含量,并收集了１９８４年以前该地区另外５种,７７个建筑材料样品中的放射性水平数据。     

Strength Development of Solidified/Stabilized Organic Waste and Optimum Treatment Design

Abstract

Artificially contaminated (spiked) natural soils were solidified/stabilized using various combinations of commonly used additives, such as lime, cement, fly ash, activated carbon, and silica fume. The effectiveness of the solidification/stabilization (S/S) processes was evaluated based on experimental findings from compaction testing, unconfined compressive shear strength, and X-ray diffraction (XRD). Correlations of limited reliability between unconfined compressive strength and penetrometer and torvane measurements were derived. Results from XRD experiments indicated that certain organic contaminants (i.e., naphthalene and pyrene) might impact the S/S processes for a given combination of additives. The type and amount of organic contaminants also affected the pozzolanic reactions. Specifically, the absence or small peak intensity of pozzolanic product XRD patterns for a given combination of additives was a good indication that the type and the amount of organic contaminant present inhibited pozzolanic reactions. This phenomenon was tested and confirmed for actual field-contaminated samples.     

Resource recycling through artificial lightweight aggregates from sewage sludge and derived ash using boric acid flux to lower co-melting temperature

This study focuses on artificial lightweight aggregates (ALWAs) formed from sewage sludge and ash at lowered co-melting temperatures using boric acid as the fluxing agent. The weight percentages of boric acid in the conditioned mixtures of sludge and ash were 13% and 22%, respectively. The ALWA derived from sewage sludge was synthesized under the following conditions: preheating at 400 degrees C 0.5 hr and a sintering temperature of 850 degrees C 1 hr. The analytical results of water adsorption, bulk density, apparent porosity, and compressive strength were 3.88%, 1.05 g/cm3, 3.93%, and 29.7 MPa, respectively. Scanning electron microscope (SEM) images of the ALWA show that the trends in water adsorption and apparent porosity were opposite to those of bulk density. This was due to the inner pores being sealed off by lower-melting-point material at the aggregates'surface. In the case of ash-derived aggregates, water adsorption, bulk density, apparent porosity, and compressive strength were 0.82%, 0.91 g/cm3, 0.82%, and 28.0 MPa, respectively. Both the sludge- and ash-derived aggregates meet the legal standards for ignition loss and soundness in Taiwan for construction or heat insulation materials.     

Pozzolanic reactivity of the synthetic slag from municipal solid waste incinerator cyclone ash and scrubber ash

This study investigates the pozzolanic reactions and compressive strength of the blended cement manufactured using synthetic slag obtained from municipal solid waste incinerator (MSWI) cyclone ash and scrubber ash as partial replacement of portland cement. The synthetic slag was made by co-melting the MSWI scrubber ash and cyclone ash mixtures at 1400 degrees C for 30 min. Following pulverization, the different types of slag were blended with cement as cement replacement at ratios ranging from 10 to 40 wt %. The synthetic slag thus obtained was quantified, and the characteristics of the slag-blended cement pastes were examined. These characteristics included the pozzolanic activity, compressive strength, hydration activity, crystal phases, species, and microstructure at various ages. The 90-day compressive strength developed by slag-blended cement pastes with 10 and 20 wt % of the cement replaced by the synthetic slag outperformed ordinary portland cement by 1-7 MPa. X-ray diffraction species analyses indicated that the hydrates in the slag-blended cement pastes were mainly portlandite, the calcium silicate hydrate gels, and calcium aluminate hydrate salts, similar to those found in ordinary portland cement paste. Differential thermal and thermogravimetric analysis also indicated that the slag reacted with portlandite to form calcium silicate hydrate gels.     

Application of coupled thermostatted columns in civil engineering and for leaching heavy metals of wastes from foundry sands and mining industry

For many years, the mining industry at Pachuca Hidalgo, Mexico, has produced silver and gold through a cyanide process. Solid wastes (tailings) of this process have been deposited close to centres of population. Many of the metals in these wastes are dispersed via wind and rain, and can be toxic to flora and fauna. Foundry sands are wastes, produced by the automotive industry, the metallurgy industry and others, which are contaminated with many metals such as Fe, Cr, Zn, Pb, Au Ag, Ti, Ge, Co, As, Al, etc. We have previously patented a process for the extraction of toxic and valuable metals from foundry sands using a thermostatted column. The results of this study indicate that the process and the device could be used for removing heavy metals from tailings. In this research both types of waste (foundry sands and tailings) were leached using four coupled thermostatted columns. The presence of heavy metals in the solid wastes was studied using the ICP-AS technique and scanning electron microscopy, and to study the structure we used X-ray diffraction. After leaching we used the solid wastes (without toxic metals) to produce bricks. The mechanical properties of the bricks were assessed against international standards.     

Pilot-Scale Evaluation of an Incinerability Ranking System for Hazardous Organic Compounds

The U.S. Environmental Protection Agency’s (EPA) hazardous waste incinerator performance standards specify a minimum destruction and removal efficiency (DRE) for principal organic hazardous constituents (POHCs) designated in the incinerator waste feed. In the past, selection of appropriate POHCs for incinerator trial burns has been based largely on their heats of combustion. Attempting to improve upon this approach, the University of Dayton Research Institute (UDRI), under contract to the EPA Risk Reduction Engineering Laboratory, has developed a thermal stability-based ranking of compound "incinerability". The subject study was conducted to evaluate the laboratory-developed ranking system in a pilot-scale incinerator.

Mixtures of POHCs, spanning the ranking scale from most- to least-difficult to destroy (Class 1 to Class 7, respectively), were prepared and combined with a clay-based sorbent matrix. These mixtures were then fed into the rotary kiln incineration system at the U.S. EPA Incineration Research Facility (IRF). In a series of five tests, the following conditions were evaluated: baseline/ typical operation; thermal failure (quenching); mixing failure (overcharging); matrix failure (low feed H/CI ratio); and a worst-case combination of the three failure modes.

Under baseline conditions, mixing failure, and matrix failure, kiln-exit DREs for each compound were comparable from test to test. Operating conditions in these 3 modes appeared to be sufficient to effect considerable destruction (greater than 99.99 percent DRE) of all compounds. As a result, separation of the highest-ranked POHCs from the lowest-ranked POHCs according to observed DRE was not possible; a correlation between POHC ranking and DRE could not be confirmed.

A correlation between predicted and observed incinerability was more evident for the thermal failure and worst-case conditions. Kiln-exit DREs for the four POHCs predicted to be most stable (those in Classes 1 and 2) ranged from 99% to 99.99% under these conditions, and were generally lower than DREs for the POHCs predicted to be more easily destroyed. Statistically significant correlations above the 99 percent and 93 percent confidence intervals were identified for the thermal-failure and worst-case tests, respectively.     

Source apportionment of PM10 and PM2.5 in five Chilean cities using factor analysis

Chile is a fast-growing country with important industrial activities near urban areas. In this study, the mass and elemental concentrations of PM10 and PM2.5 were measured in five major Chilean urban areas. Samples of particles with diameter less than 10 microm (PM10) and 2.5 microm (PM2.5) were collected in 1998 in Iquique (northern Chile), Valparaiso, Vi?a del Mar, Rancagua (central Chile), and Temuco (southern Chile). Both PM10 and PM2.5 annual mean concentrations (PM10: 56.9-77.6 microg/m3; PM2.5: 22.4-42.6 microg/m3) were significantly higher than the corresponding European Union (EU) and U.S. Environmental Protection Agency (EPA) air quality standards. Moreover, the 24-hr PM10 and PM2.5 U.S. standards were exceeded infrequently for some of the cities (Rancagua and Valparaiso). Elements ranging from Mg to Pb were detected in the aerosol samples using X-ray fluorescence (XRF). For each of the five cities, factor analysis (FA) was applied to identify and quantify the sources of PM10 and PM2.5. The agreement between calculated and measured mass and elemental concentrations was excellent in most of the cities. Both natural and anthropogenic sources were resolved for all five cities. Soil and sea were the most important contributors to coarse particles (PM10-PM2.5), whereas their contributions to PM2.5 were negligible. Emissions from Cu smelters and oil refineries (and/or diesel combustion) were identified as important sources of PM2.5, particularly in the industrial cities of Rancagua, Valparaiso, and Vi?a del Mar. Finally, motor vehicles and wood burning were significant sources of both PM2.5 and PM10 in most of the cities (wood burning was not identified in Iquique).     

脱硫灰用作钙质材料制备蒸压加气混凝土砖块

为实现半干法脱硫灰的资源化利用,采用半干法脱硫灰作为蒸压加气混凝土砖块中的钙质材料。对脱硫灰进行预处理,使其在含水量20%条件下消化2 h后,烘干。在其他条件不变情况下,掺入经过预处理后的脱硫灰,砖块的抗压强度会有明显的提高。增加经过预处理后的脱硫灰的掺入量,可以在不影响砖块的抗压强度性能的基础之上,降低砖块的干燥收缩值和导热系数,同时提高砖块的抗冻性能和保温隔热性能。     

A comparison between sludge ash and fly ash on the improvement in soft soil

In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4-2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20-30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil.     

Acoustic barriers obtained from industrial wastes

Acoustic pollution is an environmental problem that is becoming increasingly more important in our society. Likewise, the accumulation of generated waste and the need for waste management are also becoming more and more pressing. In this study we describe a new material--called PROUSO--obtained from industrial wastes. PROUSO has a variety of commercial and engineering, as well as building, applications. The main raw materials used for this environmentally friendly material come from slag from the aluminium recycling process, dust from the marble industry, foundry sands, and recycled expanded polystyrene from recycled packaging. Some natural materials, such as plastic clays, are also used. To obtain PROUSO we used a conventional ceramic process, forming new mineral phases and incorporating polluted elements into the structure. Its physical properties make PROUSO an excellent acoustic and thermal insulation material. It absorbs 95% of the sound in the frequency band of the 500 Hz. Its compressive strength makes it ideal for use in ceramic wall building.     

Hydration properties of eco-cement pastes from waste sludge ash clinkers

Three types of hydraulic cements have been developed by incorporating sludge ash from a primary sewage treatment plant and a water purification plant, as well as slag from steelworks (ferrate), as a partial replacement for clay, silica, alumina, and iron oxide in raw cement meal. The raw meal for the pre-determined recipes was prepared by heating it to 1400 degrees C for 6 hr in a clinkerization process, using a simulated incinerator and smelter. The major components of ordinary Portland cement, C3S, C2S, C3A, and C4AF, were all found in the clinkers. Of the three types of eco-cements, the eco-cement A paste was most similar to ordinary Portland cement in terms of composition and compressive strength development, while the eco-cement B paste showed early strength development. The differential thermal analysis species analyses indicated that the hydrates in the eco-cement pastes were mainly calcium hydroxide and CSH gels, like those found in ordinary Portland cement paste. Moreover, the degree of hydration, as determined by nuclear magnetic resonance, increased in all eco-cement pastes with an increasing curing age. The results indicate that it indeed is feasible to use sludge ash and ferrate to replace up to 20% of the mineral components of raw materials for cement.     

钢渣掺量对泡沫混凝土砌块性能的影响

泡沫混凝土是一种环保、节能的保温隔热材料,以其优良的保温性能,受到越来越多研究者的关注。对钢渣的特性进行了分析测试,对钢渣不同掺量对泡沫混凝土砌块特性的影响进行了研究,结果表明,采用添加5％～35％钢渣所制备的钢渣泡沫混凝土砌块,其密度等级为JC／T1062—2007中的B10级,掺人5％、15％钢渣的泡沫混凝土抗压强度达到A3．5等级,掺人25％、35％钢渣的泡沫混凝土抗压强度达到A2．5等级。随着钢渣掺量的增大,抗压强度、抗折强度降低,吸水率增大。在同一钢渣掺量的情况下,泡沫混凝土砌块的抗压强度变化率增加显著,而且随着钢渣的加入量升高而增大。钢渣的加入有利于提高泡沫混凝土砌块的后期抗压强度。     

Advanced oxidation treatment of physico-chemically pre-treated olive mill industry effluent

In this study, the applicability of physico-chemical methods was investigated for the pre-treatment of the olive mill effluents prior to the discharge into the common sewerage ending with a municipal wastewater treatment plant. The samples were taken from an olive oil industry operated as three-phase process located in Turkey. Various pre-treatment methods including acid craking, polyelectrolyte and lime additions were applied. Advanced oxidation study using Fenton's process was also investigated following pre-treatment by acid cracking and cationic polyelectrolyte. Acid cracking alone gave satisfactory treatment efficiencies and polyelectrolite additions to the acid-cracked samples enhanced treatment efficiency. Since a complete treatment plant is available at the end of the sewer system, results indicated that the effluents of the investigated industry could be discharged into the municipal sewerage in the case of total chemical oxygen demand (COD(tot)), suspended solid (SS) and volatile suspended solid (VSS) concentrations according to the Turkish Water Pollution Control Regulation after pre-treatment with 5 ppm anionic polyelectrolyte following acid cracking. The minimum COD(tot), SS and VSS removals were observed when raw wastewater was pre-treated with lime and the discharge standards to the municipal sewer system could not be met. Advanced oxidation with Fenton's process was applied after acid cracking and cationic polyelectrolyte treatment in order to investigate further reduction in chemical oxygen demand (COD) concentration for minimizing the influence of this industrial discharge on the existing municipal wastewater treatment plant. Results indicated that COD(tot) removal increased up to 89% from 74% after Fenton's oxidation for the acid cracked samples in which cationic polyelectrolite (10 ppm) was added.