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.     

Profiling hazardous waste generation for management planning

Results of a survey of the hazardous wastes generated by the industrial sector of the United States' economy are presented. Although data availabilityA method is also presented for building the results of waste generation surveys into hazardous waste management models. This requires the creation of a     

Failure mode analysis of a diesel motor crankshaft

A failure mode analysis of a diesel motor (110 kW) crankshaft from an automobile vehicle is presented. After 120,000 km in service, an abnormal vibration was detected which was increasing with the time. The diesel motor was first disassembled for determining the root cause, however without success. No defect was detected, but since a suspicion of damage was present, and being this failure recurrent in this type of diesel motor series, the crankshaft was disassembled again. Then the crankshaft was subjected to a simple vibration analysis and a preliminary indication of possible existence of a crack was concluded. The crankshaft was then replaced by a new one, and the old was subjected to a failure analysis for determining the root cause. A crack was found at the crankpin web-fillet and after a complete opening of the crack, the failure analysis showed that fatigue was the dominant failure mechanism. Observations were carried out by optical and Scanning Electronic Microscope. Material defects at the crack initiation zone were not found. The root cause of damage seems to be a misalignment of the main journals and a weakness of design close to the gear at the region where the crack was initiated. Therefore, probably a poor design and a deficient assembling of the crankshaft helical gear coupled to the main journal end was the first cause of the failure.     

Wet air oxidation for hazardous waste control

The Wetox® process has been proven effective on a variety of industrial and municipal waste streams. Many of these streams contained chemicals whichAn advantage of the technology is that elements such as sulphur, chlorine and nitrogen are retained in solution, thus minimizing any potential air pollThe first commercial Wetox system has been installed at a chemical company in Ontario in the spring of 1982. This unit is being designed to treat about     

Failure mode analysis of a damaged shackle part used for container transportation

Failure analysis on a shackle part broken during service of container transportation was carried out. Fractured surface around crack initiation site was a little oxidized and there were dendritic structure and intergranularly fractured surface around crack initiation site. Mixture of pearlite and bainite in dendritic region was observed and martensitic structure was observed in adjacent area. On the other hand, microstructure of core region was mixture of pearlite and ferrite. It was considered that the dendritic structure was generated due to repair-welding process and catastrophic failure occurred due to the lack of ductility caused by improper post-heat treatment after repair welding.     

Containment of uncontrolled hazardous waste sites

Conventional as well as new approaches to contain hazardous waste sites are examined. Some recommendations on how to deal with the uncertainty in the engineering containment of these sites are made.     

Factors affecting hazardous waste solidification/stabilization: a review

Solidification/stabilization is accepted as a well-established disposal technique for hazardous waste. As a result many different types of hazardous wastes are treated with different binders. The S/S products have different property from waste and binders individually. The effectiveness of S/S process is studied by physical, chemical and microstructural methods. This paper summarizes the effect of different waste stream such as heavy metals bearing sludge, filter cake, fly ash, and slag on the properties of cement and other binders. The factors affecting strength development is studied using mix designs, including metal bearing waste alters the hydration and setting time of binders. Pore structure depends on relative quantity of the constituents, cement hydration products and their reaction products with admixtures. Carbonation and additives can lead to strength improvement in waste-binder matrix.     

A conflict model for the international hazardous waste disposal dispute

A multi-stage conflict model is developed to analyze international hazardous waste disposal disputes. More specifically, the ongoing toxic waste conflicts are divided into two stages consisting of the dumping prevention and dispute resolution stages. The modeling and analyses, based on the methodology of graph model for conflict resolution (GMCR), are used in both stages in order to grasp the structure and implications of a given conflict from a strategic viewpoint. Furthermore, a specific case study is investigated for the Ivory Coast hazardous waste conflict. In addition to the stability analysis, sensitivity and attitude analyses are conducted to capture various strategic features of this type of complicated dispute.     

Failure mode analysis of two crankshafts of a single cylinder diesel engine

This paper reports an investigation carried out on two damaged crankshafts of single cylinder diesel engines used in agricultural services for several purposes. Recurrent damages of these crankshafts type have happened after approximately 100 h in service. The root cause never was imputed to the manufacturer. The fatigue design and an accurate prediction of fatigue life are of primordial importance to insure the safety of these components and its reliability. This study firstly presents a short review on fatigue power shafts for supporting the failure mode analysis, which can lead to determine the root cause of failure. The material of these damaged crankshafts has the same chemical composition to others found where the same type of fracture occurred at least ten years ago. A finite element analysis was also carried out in order to find the critical zones where high stress concentrations are present. Results showed a clear failure by fatigue under low stress and high cyclic fatigue on crankpins.     

Failure analysis on abnormal corrosion of economizer tubes in a waste heat boiler

Repeated shell side corrosion occurred on economizer tubes of a waste heat boiler. In order to find out the root cause of the corrosion, a series of characterization methods were conducted. First of all, the tubes were proved to be qualified A106 Gr.A steel in chemical compositions and metallographic structures. Then, both macroscopic and microscopic characteristics of the failed tube were observed thoroughly. After that, phase compositions of the deposits collected from failed tubes were analyzed. Content of sulfur and nitrogen of deposits was determined precisely as well. The results revealed that repeated failures were primarily owing to sulfuric acid dew point corrosion and the sulfur mainly came from waste liquid of methyl methacrylate (MMA). Finally, mechanisms of the failure were discussed in detail and practical countermeasures were put forward.     

Demonstration plasma gasification/vitrification system for effective hazardous waste treatment

Plasma gasification/vitrification is a technologically advanced and environmentally friendly method of disposing of waste, converting it to commercially usable by-products. This process is a drastic non-incineration thermal process, which uses extremely high temperatures in an oxygen-starved environment to completely decompose input waste material into very simple molecules. The intense and versatile heat generation capabilities of plasma technology enable a plasma gasification/vitrification facility to treat a large number of waste streams in a safe and reliable manner. The by-products of the process are a combustible gas and an inert slag. Plasma gasification consistently exhibits much lower environmental levels for both air emissions and slag leachate toxicity than other thermal technologies. In the framework of a LIFE-Environment project, financed by Directorate General Environment and Viotia Prefecture in Greece, a pilot plasma gasification/vitrification system was designed, constructed and installed in Viotia Region in order to examine the efficiency of this innovative technology in treating industrial hazardous waste. The pilot plant, which was designed to treat up to 50kg waste/h, has two main sections: (i) the furnace and its related equipment and (ii) the off-gas treatment system, including the secondary combustion chamber, quench and scrubber.     

Recycling hazardous jarosite waste using coal combustion residues

Increase in environmental concern due to improper management of both hazardous and non hazardous wastes released from different industrial process prioritized the necessity for the innovation research. In this context, this paper deals with the immobilization of jarosite waste released from the zinc industry and converting it into a value added product using coal combustion residues (CCRs) through solidification/stabilization (s/s) and sintering process. Experiments were conducted using different ratio of jarosite waste and clay soil with varying concentration of CCRs. The optimized experimental results (using jarosite waste and clay soil ratio of one with 15% CCRs) showed that it is possible to make a composite having desirable mechanical properties such as compressive strength (50–81 kg/cm²); water absorption (13–17%); shrinkage (11–32%); and density (1.6–1.8 gm cm^?3) to use as a construction material. Under solid state sintering process, with the application of CCRs, the mineral phases such as X Fe₃ (SO₄)₂(OH)₆ [where X = K and NH₄], 2Fe₂O₃SO₃.5H₂O, PbSO₄, CaSO₄ in jarosite waste were transformed into a silicate matrices. The leachate studies confirmed that the toxic elements such as Cd, Pb, etc. were immobilized in the jarosite waste composite and meeting the USEPA TCLP toxicity norms for safe utility. The composite product thus developed has showed potential for recycling jarosite waste in construction sector leading to cross sector waste recycling.     

Removal of hazardous dye congored from waste material

The present paper is aimed to investigate and develop cheap adsorption methods for color removal from wastewater using waste material sawdust as adsorbent. Sawdust, a biosorbent, was successfully utilized in removing a water soluble azo dye, congored from wastewater. The paper incorporates effect of pH, temperature, amount of adsorbent, contact time, concentration of adsorbate, particle size on adsorption. Specific rate constants of the processes were calculated by kinetic measurements and a first order adsorption kinetics was observed in each case. Langmuir and Freundlich adsorption isotherm models were then applied to calculate thermodynamics parameters as well as to suggest the plausible mechanism of the ongoing adsorption processes. In order to observe the quality of wastewater COD measurements were also carried out before and after the treatments. A significant decrease in the COD values was observed, which clearly indicates that adsorption method offer good potential to remove congored from wastewater.     

Assessing emergency preparedness in support of hazardous facility risk analyses: Application to siting a US hazardous waste incinerator

Increasing public resistance to hazardous materials transportation and facility operation has elicited a number of suggestions for improved risk communication, early community participation, and provision of incentives. Another potentially useful but hitherto neglected method of addressing local opposition to hazardous facility siting involves community emergency preparedness for a release of hazardous materials. This paper describes a procedure for analyzing local emergency preparedness in accordance with operational guidance from federal agencies in the United States and scientific principles derived from international research on disasters. This procedure identifies vulnerable areas of a community and assesses the capability of the community to take timely and effective protective actions including evacuation and sheltering in-place. Response capability is first assessed by verifying that local emergency response plans address the elements defined in state and federal guidance. Next, implementation analyses are conducted to determine whether the four critical functions of hazard detection and notification, protective action decision making, warning and public information, and protective action implementation can be accomplished with available resources under local conditions. These analyses indicate the degree to which formally designated emergency response activities of community agencies, as outlined by its Emergency Operations Plan (EOP), together with the informal social processes of emergency response known to operate in disasters, provide reasonable assurance of prompt and effective protective action by the public. Results of these analyses can provide administrative and judicial review processes with conclusions on the overall adequacy of local emergency preparedness, local emergency responders with suggestions as to which emergency preparedness improvements should be undertaken, and local residents with a better understanding of risk mitigation measures.     

Failure analysis: Vapor overheads discharge line for high level radioactive waste evaporator

A 2 in. schedule 40 steel (60.3 mm diameter, 3.91 mm wall) core pipe in an evaporator overheads discharge line broke at several locations downstream from a section of the line that bridges a road. The failure occurred during pump restart. Fish mouth openings that developed along the pipe seams were initiated at lack of fusion defects in the pipe welds. Full drainage of the water from the pipe did not occur when the pump was shut down because such drainage created an upstream vacuum in the piping system. Freezing of water in the pipe (the line was not heat traced) and water hammer during pump restart each contributed to the extensive deformation and tearing observed at the breaks. The weld flaws served as crack initiation sites and the water hammer provided the overpressure that led to the fish mouth fracture. The pipe was replaced and a vacuum break was installed to eliminate the drainage problem.     

Solidification/stabilization of hazardous waste sludge obtained from a chemical industry

In this study, treatment sludge obtained from a chemical-metal finishing industry, which contained potentially toxic heavy metals and organics, was characterized, and the performance of the solidification/stabilization (S/S) of the sludge was discussed. The hazard characteristics of the waste were determined by means of extraction procedure toxicity test and DIN 38414-S4 Test, as defined in both Turkish and USEPA regulations. S/S studies were conducted using Portland cement to solidify the sludge containing high concentrations of total organic carbon, Cr, Cu, Hg, Ni, Pb, and Zn. The waste/binder ratios of 36 sludge specimens were kept between 0/100 and 40/100. The specimens were cured at room temperature for 7, 28, and 90 days. The compressive strengths of the specimens were measured to determine the feasibility of using solidified waste sludge as construction materials. The compressive strength values indicated that specimens could be potentially used as construction materials. The heavy metal and organic contents of the extracts of each specimen were detected in concentrations which were lower than the standard concentrations in EPTox and DIN 38414-S4 leaching procedures for the most part.     

Wet air oxidation — A treatment means for aqueous hazardous waste streams

Wet air oxidation (WAO) is a process in which dissolved or suspended oxygen-demanding components of a wastewater are oxidated at elevated temperature and pressure using an oxygen-containing gas such as air bubbling through the aqueous phase. In this paper the increasing use of WAO in detoxification of hazardous wastes is described. The cost of WAO is compared with that of incineration. Various present day applications of WAO are described in detail.