Conventional equations to estimate sampling variability are insufficient because they are based on the assumption that wastes consist of a single composition. In this paper, we applied sampling equations for multicomposition wastes obtained theoretically in the previous paper to four wastes, and estimated required sampling weights. Our result showed that 25 kg of sampling weight and 110 g of subsampling weight are required for the Japanese standard leaching test No. 13 for wastes containing many compositions. However, the coefficient of variation of the test results under the sampling conditions was estimated to be 1.1. It was concluded, therefore, that wide variations under practical sampling conditions must be accepted. We also then examined a statistical determination method of test results that take variability into consideration. The examination showed that test results would exceed the standard values with more than 10% probability if the average test value is not less than 0.6 times the standard value.

View full abstract

It has already been confirmed that the reduction of lead is dependent on the insolubility of the lead ion which was converted into basic lead carbonate (2PbCO₃⋅ Pb (OH) ₂) by precipitation reaction.
In this investigation, we examined the influences of pH and anions on the insolubility of the lead ion by utilizing slag leachates instead of slags. The pH value of the slag leachate was adjusted across a range of pH values from 9.2 to 11.4 under solid liquid ratio (S/L) . Regarding anions, we examined with chloride, sulfate, acetate and nitrate which were ionized to Cl ion, SO₄ ion, CH₃COO ion and NO₃ ion, which might be leachated in the incineration ash and organic matter. Consequently, it was confirmed that basic lead carbonate (2PbCO₃ ⋅ Pb (OH) ₂) was best formed with S/L (2 w/v%) and a pH value of about 10.5. When chloride concentration was about the same as that of the lead compound's, a kind of lead oxychloride, laurionite (PbCl (OH) ) was predominantly formed and basic lead carbonate (2PbCO₃⋅ Pb (OH) ₂) was not formed. However, lead sulfate (PbSO₄) was predominantly formed when the SO₄ ion and the CI ion coexisted. Basic lead carbonate (2PbCO₃⋅ Pb (OH) ₂) was formed when CH₃COO ion and NO₃ ion existed. As a result, it was confirmed that coexistent salts with slag leachate effected the reduction of lead.

View full abstract

During the process of new policy formation which has a great effect on the everyday lives of residents, it is essential to accurately understand and take into full consideration public opinions and values. In this thesis, using the Contingent Valuation Method (CVM), we threw light upon the policy needs for separated waste collection of containers and packaging in Chiba City, and examined the feasibility of the separated waste collection program by assessing the cost affordability for the residents. In addition, using the results of the questionnaire survey, we estimated in great detail the value Chiba City citizens place on waste disposal projects for their city, and found an enormous difference between the public valuation and the actual cost of the project. As a result of these two case studies, we discovered that CVM can be effectively applied to the formation and assessment of waste management policies, as CVM is particularly efficient in grasping the possibilities of policy consensus through valuations.

View full abstract

Hydrogen was generated spontaneously from wheat bran moistened with de-ionized water and kept warm in an incubator at 36°C overnight. The conditions for spontaneous hydrogen production from wheat bran were examined, 40 g of wheat bran, 15 g of trypticase soy broth powder and 500 mL of de-ionized water were mixed in a 1, 000 mL flask and kept in a 45°C water bath. Gas production began about six hours after incubation, with the amounts of gas increasing rapidly thereafter. When the pH of the culture was maintained at pH 5.2, the hydrogen gas generation peaked at about 2, 400 mL in total. The initial weight of the wheat bran decreased from 40 g by about 10 g after spontaneous hydrogen production. From these results, it was found that 60 mL/g of hydrogen gas was produced from wheat bran and 240 mL/g was produced from the material consumed. As a control test, the quantity of hydrogen generated from glucose was compared with that generated from wheat bran. 10 g of wheat bran or 5g of glucose, and 15g of trypticase soy broth powder in 450 mL of de-ionized water were sterilized in an autoclave, mixed with 50 mL of culture of the hydrogen-producing bacterial strain AM21B in an anaerobic glove box and incubated at 37°C and pH 5.7. From the 10 g of wheat bran and the 5g of glucose, 1, 328 mL and 1, 776 mL of hydrogen were produced, respectively. These results show that 133 mL/g of hydrogen from wheat bran and 355 mL/g from glucose were produced using AM21B, and the amount of hydrogen gas produced from 10 g of wheat bran was equivalent to that from 3.75 g of glucose. In addition, the composition of the gas generated spontaneously from wheat bran was approximately 70% hydrogen, 28% carbon dioxide and about 2% nitrogen and oxygen.

View full abstract

We tried to develop a new reclamation method at a sea area landfill site. This method decreases the risk of environmental pollution from landfilled solid waste before reclamation. A safe landfill is thereby created. This method has two processes: leaching and separation. The first process is slurry transportation: soluble heavy metals in the solid waste are removed by dissolving them in seawater. The second process is separation: incineration ash is separated to reduce environmental risk.
This experiment used a machine to agitate the ash in seawater to simulate agitation by slurry transportation. As a result, the process of separating fine particles on the incineration ash surface was completed in about 5 minutes. Furthermore, increasing the L/S ratio in the slurry transportation accelerated the leaching of Cr (VI) from the incineration ash. In addition, the upper portion of incineration ash that remained in a 2 mm sieve after agitation showed heavy metal concentration in the leachate that was below the quantitative limit value. These results demonstrate that separation should be made by a 2 mm sieve to develop landfills with low environmental pollution risk.

View full abstract

In the recycling of waste wood from building demolition, caution is necessary in handling the toxic substances that were used in preservative treatment, for example, CCA that has been used in building foundations. Waste wood resulting from demolition of buildings often contains CCA and other heavy metals from inorganic paints and other dusts. However, there is no information about the stream of heavy metals contained in construction and demolition waste wood. We investigated the chip-making facilities that treat waste wood in Saitama Prefecture, and measured the mass balance of heavy metals. We found that at least 50% of the heavy metals are sorted out as fuel, and 5 to 70% are separated into dust as a result of crushing and sieving processes.

View full abstract