Resources and Conservation最新文献

There are 182 auto shredder processors in the United States and 249 in the world with a capacity of 16.3 Tg [1]. When shredding automobiles and obsolete appliances (white goods) an average of 254 Mg of ferrous and nonferrous metals and shredder residue are generated per shredder per eight hour production shift.

There were no markets for the 3.4 Tg shredder “fluff” (non-metallic, light material) produced which is traditionally deposited in landfills. This paper describes two possible markets for this heterogeneous material: a possible boiler fuel and a cover material for landfills.

Two alternative ways to process a wastewater that contains Cu(I) and Cu(ll) were investigated experimentally on a laboratory scale: ion exchange and hydrometallurgical extraction. The Cu(I) and a small fraction of the Cu(II) are present in the wastewater in the form of negatively charged halogenide complexes due to the high chloride and bromide content (4kmol/m³) of the water.

Anion exchange resins were chosen to remove the copper from the solution. none of the resins that were tested gave fully satisfactory results. The ion exchange alternative was rejected.

Hydrometallurgical extractions of solutions of Cu(I) or Cu(ll) containing NaCl and NaBr were carried out using a mixture of oleic acid and cyclohexa-noneoxime dissolved in toluene as extractiot. The experiments showed that the extraction efficiency increases with increasing pH of the water solution and with decreasing chloride and bromide concentration. The extraction efficiency for Cu(II) is very high at pH = 5. The copper can be stripped from the organic phase by means of 1N sulfuric acid even if CuSO₄.5H₂O crystals develop in the latter phase.

The extraction efficiency of Cu(I) from the salt solution proved to be poor. A search for other extractants for the Cu(I) ions was unsuccessful. Therefore the Cu(I) in the wastewater had to be oxidized to Cu(II) which can then be extracted.

The above leads to a copper removing process which consists of the following steps:

• 1.

  1. Removal of the methanol that is also present in the wastewater in a continuous distillation column.

• 2.

  2. oxidation of Cu(I) to Cu(II) with air.

• 3.

  3. Hydrometallurgical extraction of Cu(ll) by oleic acid in toluene in a three stage countercurrent extractor. The remaining copper concentration in the waste stream is reduced to a few ppm. Crystals of CUSO₄.5H₂O are obtained in the subsequent stripping of the organic phase.

A cost estimate of the process is presented.

An overview is given of the anaerobic treatment of concentrated organic municipal wastes under spontaneous conditions in -landfills and under controlled reactor conditions. Biogas capture in landfills offers a potential to recover energy and furthermore to reduce the extent of air, water and soil pollution by the landfill. The technology is quite simple to install and apply and can be economically interesting if a convenient consumer of the gas is located in the vicinity of the landfill. Yet, optimisation of this in-situ fermentation is urgently needed. With regard to the in-reactor technology, particular attention is given to a newly developed dry anaerobic composting process. This concerns a solid state fermentation process for the stabilization of the organic fraction of solid household refuse. The process consists of an intensive anaerobic fermentation at 30–35 X total solids and a temperature of 35 °C (mesophilic) or 55 °C (thermophilic), followed by a post digestion. It produces both biogas and a commercial humus-like endproduct. The results obtained over a 1 year period in a pilot plant of 56 m3 have demonstrated the feasibility of the process for large scale application. Gas production rates of 6 to 8 m³ per m³ reactor per day were obtained at a retention time of 12 to 18 days under thermophilic conditions. The gas yield per ton of raw organic fraction amounted to 180 m³ of biogas with a methane content of 55 %.

Materials recovery from refuse, not including refuse-derived fuels, has not grown as quickly as energy recovery. There is various anectdotal evidence that the number of source separation programs is steadily increasing, but they are not producing significant quantities of materials compared to what is available. A few mechanical sorting plants are separating and selling magnetic metals, aluminum and glass. Most of the plastic recovered is in the form of discarded beverage bottles. A major reason for the low growth is that secondary materials are marginal sources of supply for manufacture and secondary materials from refuse are marginal supplies of last resort.

Energy recovery from refuse is on the upswing, after about a five year hiatus (from 1979 to 1984) with a growing market share for mass burning compared to refuse-derived fuel in various forms. The trend line for increased capacity predicted in 1977 continues; it is based on the assumption that a municipality will install an energy from waste plant when other municipalities have done so (first order rate equation). The predicted exponential growth in processing capacity continues with some indication of a slowing of the rate.

Although incineration or mass burning of refuse, coupled to heat and energy recovery, has come back into prominence recently, the technology is well known. The main advances have been in the preparation, production and combustion of refuse-derived fuels. Recent findings and studies in progress are summarised. Refuse-derived fuel technology is still being developed and the encouraging results to date suggest that this will be a growth area for the future.

Baumrinde ist ein wertvoller Biomasse-Rohstoff and kann heute nicht mehr als “Abfall” betrachtet werden. Neben der schon länger ausgeübten thermischen Verwertung wird im folgenden Beitrag vor allem die Verwertung als Bodenverbesserer beschrieben. Damit kann Torf substituiert werden and die Ausbeutung der letzten Torfmoore mit der damit verbundenen Naturzerstbrung kann verhindert werden.

A range of fluidised bed hot gas generators and boilers have been developed by Babcock Worsley in collaboration with the UK National Coal Board. Although the designs were developed for coal firing they have been found to be satisfactory for RDF. Hot gas generators burning EDF are operating on a green crop dryerand two EDF preparation plants. A horizontal fluidised bed boiler has been operatedon EDF. A description is given of the furnace and boiler designs and the practical operating experience of burning RDF.

The main problem for the use of compost in agricultural applications is the high heavy metal content of this soil improver.

In this paper the potential sources of heavy metals present in the mixed domestic waste are quantified. The contamination mechanisms in compost production, leaching and direct contamination, are discussed and studied in controlled doping experiments. In these experiments a surplus dosage of specific potential heavy metal sources is added to a compost heap. The leaching process is followed by monitoring the local extra pollution of the surrounding organic waste in time. Information is obtained about the leachability of various components and its characteristic time scale.

To avoid leaching from, and direct contamination with non-compostable particles during composting, quite complete separation of these particles from the composting organic waste is required. Several methods are in principle possible. Experimental results obtained in various large scale operations in the Netherlands are reviewed. There are clear indications that the best results are obtained by source separation of the organic waste.

In the Netherlands governmental standards will be formulated for compost quality concerning heavy metal contents. These standards are likely to be increasingly restrictive in the years to come. It is argued that mechanical separation may reach these standards in the introductory phase, but eventually only source separation of organic waste has the potential to reach the final restrictive demands.

The paper describes in what cases, and by whom, remedial action can be taken under Belgian law in order to clean up environmentally dangerous waste deposits. Emphasis is placed on the situation in the Flemish region.

An overview is given of the general liability rules relevant to the allocation of the clean-up expenses. Especially important, in this respect, are the liability for personal fault and for defective things. Also a number of specific statutory rules imposing strict liability for clean-up expenses are described. Here the act on toxic waste of 22 July, 1974 is given special attention.

The paper describes the legal position of the most likely defendants in a suit brought by the government in order to recover clean-up costs: the operator or former operator of a disposal site, the producer of hazardous waste, and the subsequent owner of land containing waste.

The paper concludes by criticising the potential liability of the unsuspecting buyer of land formerly used as a waste-disposal site and which may result from the application of generally accepted principles of tort law. An equitable and efficient allocation system implies that clean-up costs are in the first place borne either by those originally responsible for making the remedial action necessary, or by the operator of the waste-disposal facility, or by the generator of the waste. If it is not possible to allocate the clean-up costs in this way, they should be financed from levies on polluting products or activities.