Geopolymers prepared from DC plasma treated air pollution control (APC) residues glass: properties and characterisation of the binder phase

Air pollution control (APC) residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium aluminosilicate glass (APC glass). This has been used to form geopolymer-glass composites that exhibit high strength and density, low porosity, low water absorption, low leaching and high acid resistance. The composites have a microstructure consisting of un-reacted residual APC glass particles imbedded in a complex geopolymer and C-S-H gel binder phase, and behave as particle reinforced composites. The work demonstrates that materials prepared from DC plasma treated APC residues have potential to be used to form high quality pre-cast products.

Monitoring of PCBs at facilities related with PCB-containing products and wastes in South Korea

Polychlorinated biphenyl (PCB) contents were analyzed in samples collected from facilities related to PCB-containing products or wastes in South Korea. Average concentrations of the atmospheric Σ(209) PCBs were 7420 (37.0-104,048)pgm(-3) and 16.8 (ND-34.2 )fg WHO-TEQ m(-3) in indoor air samples; and 1670 (106-13,382)pgm(-3) and 5.64 (ND-36.0) fg WHO-TEQ m(-3) in outdoor air samples. The highest levels were observed in indoor air samples from disposal facilities (7336-104,048 pg m(-3)), followed by production (330-25,057 pg m(-3)), recycling, and storage facilities, indicating that PCB emissions from PCB-containing products and wastes remains very high and the facilities related with those may be an important source to atmospheric PCBs. Principal component analysis of PCB profiles showed that the homologue patterns of PCBs in outdoor and indoor air samples collected from the facilities were similar to those of boundary air samples and PCB commercial products, e.g. Aroclor 1016, 1221, 1232 and 1242. Evaluation of the PCB mass balance in a facility, dismantling and solvent-washing PCB-contaminated transformers, showed that of the total PCBs treated in this facility, approximately 0.0022% was emitted to the atmosphere, and most was transferred to waste oil for disposal by incineration or chemical methods.

[Experimental estimation of the hazard from combustion products of waste polymeric materials]

The object of the study was waste polymeric materials. Its aim was to reveal the hazard of their combustion. Conditions occurring in the combustion of waste polymeric materials were simulated; methods for chemical analysis were used; biotesting was performed. The study revealed a high hazard from combustion products of waste polymeric materials.

A study on polypropylene encapsulation and solidification of textile sludge

The textile sludge is an inevitable solid waste from the textile wastewater process and is categorised under toxic substances by statutory authorities. In this study, an attempt has been made to encapsulate and solidify heavy metals and dyes present in textile sludge using polypropylene and Portland cement. Sludge samples (2 Nos.) were characterized for pH (8.5, 9.5), moisture content (1.5%, 1.96%) and chlorides (245mg/L, 425.4mg/L). Sludge samples were encapsulated into polypropylene with calcium carbonate (additive) and solidified with cement at four different proportions (20, 30, 40, 50%) of sludge. Encapsulated and solidified cubes were made and then tested for compressive strength. Maximum compressive strength of cubes (size, 7.06cm) containing sludge (50%) for encapsulation (16.72 N/mm2) and solidification (18.84 N/mm2) was more than that of standard M15 mortar cubes. The leachability of copper, nickel and chromium has been effectively reduced from 0.58 mg/L, 0.53 mg/L and 0.07 mg/L to 0.28mg/L, 0.26mg/L and BDL respectively in encapsulated products and to 0.24mg/L, BDL and BDL respectively in solidified products. This study has shown that the solidification process is slightly more effective than encapsulation process. Both the products were recommended for use in the construction of non-load bearing walls.

Industrial hazardous waste treatment featuring a rotary kiln and grate furnace incinerator: a case study in China

As one of the fastest developing countries, China is facing severe problems concerning hazardous waste treatment and disposal. This paper presents a new incineration technology and demonstration project in eastern China. The incineration system includes a rotary kiln, a grate furnace for burning out the kiln residue and a flue gas post-combustion chamber. Flue gas treatment and emission control is based on: a quench tower, followed by dry hydrated lime and activated carbon injection, a dual bag filter system, and a wet scrubber. It demonstrated that this incineration technology can effectively dispose of industrial hazardous waste with variable and complex characteristics. Gas emissions meet the demands of the Chinese Environmental Protection Association standard.

Optimal evaluation of infectious medical waste disposal companies using the fuzzy analytic hierarchy process

Ever since Taiwan's National Health Insurance implemented the diagnosis-related groups payment system in January 2010, hospital income has declined. Therefore, to meet their medical waste disposal needs, hospitals seek suppliers that provide high-quality services at a low cost. The enactment of the Waste Disposal Act in 1974 had facilitated some improvement in the management of waste disposal. However, since the implementation of the National Health Insurance program, the amount of medical waste from disposable medical products has been increasing. Further, of all the hazardous waste types, the amount of infectious medical waste has increased at the fastest rate. This is because of the increase in the number of items considered as infectious waste by the Environmental Protection Administration. The present study used two important findings from previous studies to determine the critical evaluation criteria for selecting infectious medical waste disposal firms. It employed the fuzzy analytic hierarchy process to set the objective weights of the evaluation criteria and select the optimal infectious medical waste disposal firm through calculation and sorting. The aim was to propose a method of evaluation with which medical and health care institutions could objectively and systematically choose appropriate infectious medical waste disposal firms.

[Biological, chemical, and radiation factors in the classification of medical waste]

The current classification of medical waste does not consider the sanitary-and-chemical hazard of epidemiologically dangerous and extremely dangerous medical waste (classes B and C). According to the results of the studies performed, the authors propose the improved classification of medical waste, which makes it possible to take into account not only infectious, radiation, and toxicological, but also sanitary-and-chemical hazards (toxicity, carcinogenicity, mutagenicity, and biological activity) of medical waste.

Integrated detoxification methodology of hazardous phenolic wastewaters in environmentally based trickle-bed reactors: Experimental investigation and CFD simulation

Centralized environmental regulations require the use of efficient detoxification technologies for the secure disposal of hazardous wastewaters. Guided by federal directives, existing plants need reengineering activities and careful analysis to improve their overall effectiveness and to become environmentally friendly. Here, we illustrate the application of an integrated methodology which encompasses the experimental investigation of catalytic wet air oxidation and CFD simulation of trickle-bed reactors. As long as trickle-bed reactors are determined by the flow environment coupled with chemical kinetics, first, on the optimization of prominent numerical solution parameters, the CFD model was validated with experimental data taken from a trickle bed pilot plant specifically designed for the catalytic wet oxidation of phenolic wastewaters. Second, several experimental and computational runs were carried out under unsteady-state operation to evaluate the dynamic performance addressing the TOC concentration and temperature profiles. CFD computations of total organic carbon conversion were found to agree better with experimental data at lower temperatures. Finally, the comparison of test data with simulation results demonstrated that this integrated framework was able to describe the mineralization of organic matter in trickle beds and the validated consequence model can be exploited to promote cleaner remediation technologies of contaminated waters.

Bimetallic Pd/Al particles for highly efficient hydrodechlorination of 2-chlorobiphenyl in acidic aqueous solution

Pd-based bimetallic materials have been widely studied for the effective hydrodechlorination (HDC) of aqueous chloroorganic compounds. However, the reaction functions of metal substrates and mechanism responsible for changes in reactivity have not been fully elucidated. Here, we synthesized Pd-based bimetals with Mg, Al, Mn, Zn, Fe, Sn, and Cu to explore the influence of metal substrates on HDC reactivity of 2-chlorobiphenyl (2-PCB). Bimetals exhibited disparate reactivity toward 2-PCB in acidic solution. Among these bimetals, Pd/Al particles presented the highest stability and relatively high reactivity to remove 2-PCB. The maintenance and regeneration of Al substrate are attributed to its particular corrosion properties which provide an efficient recycling between Al element and its oxide layer. The fresh and reacted Pd/Al samples were characterized by ICP-OES, SEM, XRD, and BET. The investigation of the pH effect on 2-PCB HDC further revealed the particular behaviour of Al surface. The effect of Pd loading amount on the HDC indicated that the optimal Pd content in terms of catalytic activity was related to the Pd dispersion degree. Finally, a mechanism for 2-PCB HDC on the Pd/Al surface was proposed.

Silicon sawing waste treatment by electrophoresis and gravitational settling

In silicon wafer manufacturing for solar cells, a great amount of hazardous sawing waste with tiny Si particles is produced, resulting in serious environmental problems. Recycling Si and abrasives from the waste is regarded as an effective solution. Based on the view of recycling, Al(2)O(3) might be good abrasives for cutting Si ingot due to its larger density and higher isoelectric point than SiC. This study reports the separation of Si/SiC and Si/Al(2)O(3) mixtures by electrophoresis and gravitational settling. At pH 9, nearly uncharged Al(2)O(3) settled quickly and the negatively charged Si moved toward the anode, leading to an obvious Si distribution on the cell bottom. The experimental results show the separation performance of Si and Al(2)O(3) at pH 9 was better than at pH 2.5, and the performance was higher than that between Si and SiC. The minimum and maximum Al(2)O(3) contents remaining in Si/Al(2)O(3) mixture were 9 wt% and 90 wt% after applying 1 V/cm for 24h at pH 9. The recovered material with high Si content can be considered as a new Si source for solar cell, and the abrasives can be reused in the sawing process.

Novel two stage bio-oxidation and chlorination process for high strength hazardous coal carbonization effluent

Effluent generated from coal carbonization to coke was characterized with high organic content, phenols, ammonium nitrogen, and cyanides. A full scale effluent treatment plant (ETP) working on the principle of single stage carbon-nitrogen bio-oxidation process (SSCNBP) revealed competition between heterotrophic and autotrophic bacteria in the bio-degradation and nitrification process. The effluent was pretreated in a stripper and further combined with other streams to treat in the SSCNBP. Laboratory studies were carried on process and stripped effluents in a bench scale model of ammonia stripper and a two stage bio-oxidation process. The free ammonia removal efficiency of stripper was in the range 70-89%. Bench scale studies of the two stage bio-oxidation process achieved a carbon-nitrogen reduction at 6 days hydraulic retention time (HRT) operating in an extended aeration mode. This paper addresses the studies on selection of a treatment process for removal of organic matter, phenols, cyanide and ammonia nitrogen. The treatment scheme comprising ammonia stripping (pretreatment) followed by the two stage bio-oxidation and chlorination process met the Indian Standards for discharge into Inland Surface Waters. This treatment process package offers a techno-economically viable treatment scheme to neuter hazardous effluent generated from coal carbonization process.

Planning for hazardous campus waste collection

This study examines a procedure developed for planning a nation-wide hazardous campus waste (HCW) collection system. Alternative HCW plans were designed for different collection frequencies, truckloads, storage limits, and also for establishing an additional transfer station. Two clustering methods were applied to group adjacent campuses into clusters based on their locations, HCW quantities, the type of vehicles used and collection frequencies. Transportation risk, storage risk, and collection cost are the major criteria used to evaluate the feasibility of each alternative. Transportation risk is determined based on the accident rates for each road type and collection distance, while storage risk is calculated by estimating the annual average HCW quantity stored on campus. Alternatives with large trucks can reduce both transportation risk and collection cost, but their storage risks would be significantly increased. Alternatives that collect neighboring campuses simultaneously can effectively reduce storage risks as well as collection cost if the minimum quantity to collect for each group of neighboring campuses can be properly set. The three transfer station alternatives evaluated for northern Taiwan are cost effective and involve significantly lower transportation risk. The procedure proposed is expected to facilitate decision making and to support analyses for formulating a proper nation-wide HCW collection plan.

The need for better public health decisions on chemicals released into our environment

Protecting the health of the public-particularly the most vulnerable groups, such as children-requires rethinking current approaches to reducing environmental risks. We review the evolving understanding of the relationship between exposure to chemicals in the environment and disease, as well as the current state of managing those chemicals. We present recommendations to improve current approaches, including changing the burden of proof so that chemicals are not presumed safe in the absence of scientific data. We also propose modernizing approaches to assessing health risks.

Study of the transference rules for bromine in waste printed circuit boards during microwave-induced pyrolysis

The production of waste printed circuit boards (WPCBs) has drawn increasing global concern, especially because the high bromine (Br) content (5-15%) places obstacles in the way of simple disposal techniques. Microwave-induced pyrolysis of WPCBs provides a promising way to dispose of these hazardous and resource-filled wastes. The transference rules for Br during microwave-induced pyrolysis have been investigated experimentally. It was found that the microwave energy could be used more efficiently to accelerate the heating rate and improve the final pyrolysis temperature by adding some activated carbon (AC) as microwave absorbents. The high temperature and rapid pyrolysis process promoted the yields of gaseous products and the decomposition of brominated compounds into hydrogen bromide and then benefited the capture of Br and the debromination of byproducts. The application of a calcium carbonate (CaCO3) layer overhead led to over 95% debromination of the liquid products and over 50% capture of the total Br. It can be concluded that the presented method is suitable for the control of Br transference in the recycling of WPCBs. This method can also be extended to the disposal of the electronic scraps.

Water management in cities of the future using emission control strategies for priority hazardous substances

Cities of the future face challenges with respect to the quantity and quality of water resources, and multiple managerial options need to be considered in order to safeguard urban surface water quality. In a recently completed project on 'Source control options for reducing emissions of Priority Pollutants' (ScorePP), seven emission control strategies (ECSs) were developed and tested within a semi-hypothetical case city (SHCC) to evaluate their potential to reduce the emission of selected European priority hazardous substances (PHSs) to surface waters. The ECSs included (1) business-as-usual, (2) full implementation of relevant European (EU) directives, (3) ECS2 in combination with voluntary options for household, municipalities and industry, (4) ECS2 combined with industrial treatment and best available technologies (BAT), (5) ECS2 in combination with stormwater and combined sewer overflow treatment, (6) ECS2 in combination with advanced wastewater treatment, and (7) combinations of ECS3-6. The SHCC approach was chosen to facilitate transparency, to allow compensating for data gaps and to decrease the level of uncertainty in the results. The selected PHSs: cadmium (Cd), hexachlorobenzene (HCB), nonylphenol (NP) and pentabromodiphenyl ether (PBDE) differ in their uses and environmental fate and therefore accumulate in surface waters to differing extents in response to the application of alternative ECS. To achieve the required reduction in PHS levels in urban waters the full implementation of existing EU regulation is prioritised and feasible combinations of managerial and technological options (source control and treatment) can be highly relevant for mitigating releases.

European experience in chemicals management: integrating science into policy

The European Union (EU) adopted the first legislation on chemicals management in 1967 with the Dangerous Substances Directive (DSD). Over time the underlying concepts evolved: from hazard identification over risk assessment to safety assessment. In 1981 a premarketing notification scheme was introduced. Approximately 10 years later a risk assessment program started for existing substances following a data collection and prioritization exercise. Integration of science into EU chemicals legislation occurred via several technical committees managed by the European Chemicals Bureau (ECB) and resulted in the Technical Guidance Document on Risk Assessment (TGD), which harmonized the risk assessment methodology. The TGD was revised several times to adapt to scientific developments. The revision process, and the risk assessments for new and existing substances, led to scientific research on chemical risk assessment and thus increased in complexity. The new EU chemicals policy REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) builds on previous experiences and aims to further enhance health and safety. REACH places the burden of proof for chemical safety on industry focusing on managing risks. REACH formalizes the precautionary principle. Furthermore, it underlines a continued scientific underpinning in its implementation, also via stakeholder involvement, and a focus on aligning with international fora.

Validation of an in situ solidification/stabilization technique for hazardous barium and cyanide waste for safe disposal into a secured landfill

The aim of the present study was to devise and validate an appropriate treatment process for disposal of hazardous barium and cyanide waste into a landfill at a Common Hazardous Waste Treatment Storage Disposal Facility (CHWTSDF). The waste was generated during the process of hardening of steel components and contains cyanide (reactive) and barium (toxic) as major contaminants. In the present study chemical fixation of the contaminants was carried out. The cyanide was treated by alkali chlorination with calcium hypochlorite and barium by precipitation with sodium sulfate as barium sulfate. The pretreated mixture was then solidified and stabilized by binding with a combination of slag cement, ordinary Portland cement and fly ash, molded into blocks (5 x 5 x 5 cm) and cured for a period of 3, 7 and 28 days. The final experiments were conducted with 18 recipe mixtures of waste + additive:binder (W:B) ratios. The W:B ratios were taken as 80:20, 70:30 and 50:50. The optimum proportions of additives and binders were finalized on the basis of the criteria of unconfined compressive strength and leachability. The leachability studies were conducted using the Toxicity Characteristic Leaching Procedure. The blocks were analyzed for various physical and leachable chemical parameters at the end of each curing period. Based on the results of the analysis, two recipe mixtures, with compositions - 50% of [waste + (120 g Ca(OCl)(2) + 290 g Na(2)SO(4)) kg(-1) of waste] + 50% of binders, were validated for in situ stabilization into a secured landfill of CHWTSDF.

Using network analysis to assess the evolution of organizational collaboration in response to a major environmental health threat

Effective inter-organizational collaboration is essential to a community's ability to leverage social and material resources for community problem solving, particularly in the face of complex public health problems. This study used network analysis to document the evolution of collaboration among 21 organizations in the Tar Creek Superfund site in northeastern Oklahoma from 1997 to 2005. The Tar Creek Superfund site was part of a major lead and zinc mining operation and suffers from widespread heavy metal contamination. An organizational network of 21 organizations and a subset of eight tribes were assessed through interviews at three points in time for density and centrality. In addition to collaboration on any topic, we examined information exchange and joint planning related to lead. Density scores were consistently higher in 2005 than in 1997 for both the full and tribal networks. Centralization indices for information exchange showed a marked reduction in the hierarchical structure of information exchange over time. Of particular note is that tribal linkages with local, state and federal agencies increased over time, as did inter-tribal linkages to address the lead issue.

Industrial hazardous waste management in Turkey: current state of the field and primary challenges

A holistic evaluation of a country's hazardous waste management (HWM) practices is useful in identifying the necessary actions to focus on. Based on an analysis of industrial hazardous waste (HW) generation in Turkey, this paper attempts to critically evaluate and report current Turkish HWM practices and discuss the primary challenges to be addressed. The generation of industrial HW for Turkey reported in 2004 was 1.195 million tons, which accounted for 7% of the total industrial solid waste (ISW) generated by the manufacturing industry, and for nearly 4.9% of the total solid waste generated in the country. The HW generated by the top five manufacturing product categories--basic metals, chemicals and chemical products, food and beverages, coke and refined petroleum, motor vehicles and trailers--accounted for 89.0% of total industrial HW. 21% of the HW generated in 2004 was recycled or reused, and 6% was sold or donated, whereas 73% was sent to ultimate disposal. 67% of the HW sent to ultimate disposal was disposed of at municipal landfills. The total capacity of the existing regional HW facilities is 212,500 tons/year, which accounts for about 24% of the HW to be disposed. Turkey has identified the HW problem in the country and enacted legislation, designated a lead agency, and promulgated rules and regulations. Several new initiatives are planned for improving HW management nationally; however, some HWM problems will be persistent due to previous and existing industrial development plans. These development policies led to the concentration of industry in regions marked by precious agricultural fields and high population density. This occurred because the government previously exhibited a default prioritization towards industrial development, leading to insufficient implementation of regulations on HW generators. Some of the problems may also be rooted in other countries that allow illegal trans boundary HW movements despite international regulations.

Dental solid and hazardous waste management and safety practices in developing countries: Nablus district, Palestine

This study investigated the dental waste management practices and safety measures implemented by dentists in the Nablus district, Palestine. A comprehensive survey was conducted for 97 of the 134 dental clinics to assess the current situation. Focus was placed on hazardous waste produced by clinics and the handling, storage, treatment and disposal measures taken. Mercury, found in dental amalgam, is one of the most problematic hazardous waste. The findings revealed that there is no proper separation of dental waste by classification as demanded by the World Health Organization. Furthermore, medical waste is often mixed with general waste during production, collection and disposal. The final disposal of waste ends up in open dumping sites sometimes close to communities where the waste is burned. Correct management and safety procedures that could be effectively implemented in developing countries were examined. It was concluded that cooperation between dental associations, government-related ministries and authorities needs to be established, to enhance dental waste management and provide training and capacity building programs for all professionals in the medical waste management field.

Sequestration of carbon dioxide (CO2) using red mud

Red mud, an aluminium industry hazardous waste, has been reported to be an inexpensive and effective adsorbent. In the present work applicability of red mud for the sequestration of green house gases with reference to carbon dioxide has been studied. Red mud sample was separated into three different size fractions (RM I, RM II, RM III) of varying densities (1.5-2.2 g cm(-3)). Carbonation of each fraction of red mud was carried out separately at room temperature using a stainless steel reaction chamber at a fixed pressure of 3.5 bar. Effects of reaction time (0.5-12 h) and liquid to solid ratio (0.2-0.6) were studied for carbonation of red mud. Different instrumental techniques such as X-ray diffraction, FTIR and scanning electron microscope (SEM) were used to ascertain the different mineral phases before and after carbonation of each fraction of red mud. Characterization studies revealed the presence of boehmite, cancrinite, chantalite, hematite, gibbsite, anatase, rutile and quartz. Calcium bearing mineral phases (cancrinite and chantalite) were found responsible for carbonation of red mud. Maximum carbonation was observed for the fraction RM II having higher concentration of cancrinite. The carbonation capacity is evaluated to be 5.3 g of CO(2)/100 g of RM II.

Production of geopolymers using glass produced from DC plasma treatment of air pollution control (APC) residues

Air pollution control (APC) residues are the hazardous waste produced from cleaning gaseous emissions at energy-from-waste (EfW) facilities processing municipal solid waste (MSW). APC residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium alumino-silicate glass. This research has investigated the optimisation and properties of geopolymers prepared from this glass. Work has shown that high strength geopolymers can be formed and that the NaOH concentration of the activating solution significantly affects the properties. The broad particle size distribution of the APC residue glass used in these experiments results in a microstructure that contains unreacted glass particles included within a geopolymer binder phase. The high calcium content of APC residues may cause the formation of some amorphous calcium silicate hydrate (C-S-H) gel. A mix prepared with S/L=3.4, Si/Al=2.6 and [NaOH]=6M in the activating solution, produced high strength geopolymers with compressive strengths of approximately 130 MPa. This material had high density (2070 kg/m(3)) and low porosity. The research demonstrates for the first time that glass derived from DC plasma treatment of APC residues can be used to form high strength geopolymer-glass composites that have potential for use in a range of applications.