[en] Land application of municipal sewage sludge and city compost as organic manures make it imperative to assess heavy-metal pollution in soils and crops. Greenhouse experiments, conducted on maize in a vertisol and an ultisol amended with various doses of dry sewage sludge and city compost from Mumbai, indicated significant increases in dry matter-yields only in the vertisol. Significantly higher concentrations of Zn, Cu, Co, Pb, Ni and Cd were obtained in plants grown in the amended ultisol, but not in the amended vertisol. As Cd is the most toxic, experiments were conducted with four contrasting soils amended with varying doses of Cd-enriched sewage sludge and city compost. Results showed significant reductions in dry-matter yields of maize shoots at the higher rates of sludge or compost in the ultisol and an alfisol, but with no significant effects in the vertisol or an entisol. The levels of Cd and Zn were significantly elevated in plants in all four soil types. There were negative residual effects from the sludge and compost amendments: dry-matter yields of a succeeding maize crop were decreased in the ultisol and alfisol. Experiments with soils amended with sludge enriched with either Cd or Zn at 80 mg kg^-1 indicated significant reductions in dry matter in all soils with Cd, but not with Zn. The results demonstrate that sewage sludges and city composts may be effectively used for maximizing crop yields, especially in vertisols and entisols. However, caution has to be exercised when using sludges containing even relatively low levels of Cd, or high levels of Zn, depending upon soil type. (author)

[en] This paper reports that there is a use for old tires; and power plants stand to gain operating, economic and public relations benefits by converting them to fuel. A major reason for their value is that fuel derived from waste tires (TDF) has a thermal value of 12,000 to 16,000 Btu/lb. Although most fuel handling system and utility boilers can accommodate TDF, a few issues remain to be resolved. These include a consistent and economic supply of tires, safe burns, and agreement between regulators and utilities. Assuming that these issues can be resolved, utilities stand to cash in on a rich fuel source and earn community recognition for helping to solve a nagging solid waste disposal problem

[en] The principles and design of condensing flue gas cooling is described in relation to wood-chip fired central heating plants. Economical aspects, and measuring programmes are also dealt with. (AB)

[en] The Clean Water Act establishes several constraints that bioenergy developers should keep in mind. These center primarily around the need to ensure that any contaminated waters or waste products are disposed of in a manner that does not harm the groundwater. In fact, states throughout the country are currently developing groundwater protection programs. These efforts to protect groundwater may, in fact, have both direct and indirect benefits to bioenergy development. For example, both dairies and feed lots will be under increasing pressure to reduce contamination from animal waste. These controls will be costly. This, together with rising energy costs, may make cogeneration for such facilities economically attractive. Alternatives to burial may also have to be found for other organic material that has been shown to cause groundwater contamination, such as onion culls, chicken carcasses, etc. This could increase its economic viability

[en] Twelve municipal solid waste incinerators, ranging in size from 80 to 1,212 tons per day, have started operating in Minnesota since 1982. The operating incinerators include modular, refuse derived fuel, field erected and fluidized bed facilities. Air pollution control equipment utilized consists of electrostatic precipitators (ESP), spray dryer/fabric filter (SD/FF) and wet scrubber systems. In this paper, results are presented for more than 30 tests completed since 1984. Results include measurements of particulate, acid gases, metals and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF). Tests at facilities using ESPs include measurements of removal efficiencies for particulate, metals and PCDD/PCDFs. An extended series of mercury test results are presented for one facility using SD/FF control. Results were reviewed for the purposes of determining permit compliance, characterizing combustion/air pollution control equipment performance and providing information for rulemaking activities. Performance trends and a discussion of future prospects for regulation of incinerators in Minnesota are also presented

[en] Review of NOx formation studies shows that NO forms in recovery furnaces primarily by two independent mechanisms, thermal and fuel. Thermal NO formation is extremely temperature-sensitive. However, theoretical predictions indicate that recovery furnace temperatures are not high enough to form significant thermal NO. Fuel NO formation is less temperature-sensitive, and is related to fuel nitrogen content. Black liquors are shown to contain 0.05 to 0.24 weight percent fuel nitrogen. Conversion of just 20% of this would yield approximately 25-120 ppm NOx (at 8% 0₂) in the flue gas, enough to represent the majority of the total NOx. Data from operating recovery furnaces show NOx emissions ranging from near zero to over 100 ppm at 8% 0₂. An apparent increase in recovery furnace NOx emissions was observed with increasing solids. This increase is much less than predicted by thermal NO formation theory, indicating that other NO formation/destruction mechanisms, such as fuel NO formation, are important. No data are available to show the relative importance of thermal and fuel NO to total NOx during black liquor combustion

[en] Biomass currently provides about 14% of the world's energy, (about 55 EJ; 1,250 M toe) and between 20 and 40 M toe in the European Economic Community. CO2 emissions resulting from biomass use are seldom considered in global carbon balances. Yet biomass can play a significant role in reducing CO2 either by acting as a reservoir or carbon or as a direct substitute for fossil fuels. Biomass energy production and use needs to be considered seriously as a CO2 neutral energy resource. The carbon cycles of fossil and biomass fuels and carbon tax incentives should be clearly interlinked in energy policy making. (author)

[en] Short communication

[en] Existing municipal systems for anaerobic digestion of biological waste are reviewed. The compost volume is smaller than with aerobic composting, i.e. the problem of what to do with the compost in urban areas would be less urgent. Anaerobic and aerobic processes are compared in principle, and the available processes are reviewed individually. (orig.)

[en] Polychlorinated dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are ubiquitous in most environmental samples, especially from the northern hemisphere. Due to the extreme toxicity of some of the PCDDs and PCDFs a very intense discussion has taken place during the last two decades with both scientific and public concern. Combustion processes and particularly municipal solid waste MSW incineration is identified as one of the major sources. An improved sampling method has been designed for the analysis of organic micro pollutants, especially PCDDs and PCDFs. The method has been validated with good results against four of the sampling methods currently used in the sampling of PCDDs and PCDFs in flue gas. Different spiking protocols have also been compared. PCDDs and PCDFs have been found in exhausts from cars fueled with gasoline. The emission level from leaded gasoline was 10 times higher as compared to unleaded gasoline. However, the congener pattern clearly shows that the environmental impact from automobile emission is negligible compared with MSW incineration. Thermal treatment of PVC and snow samples after a PVC fire clearly shows that PVC can cause formation of PCDDs and PCDFs. However, in a MSW incinerator where PVC contributes with about 50% of the chlorine load, a remove of PVC from the waste will only minorly effect the emission of PCDDs and PCDFs. A better way to decrease the emission levels of PCDDs and PCDFs is to optimize the burning conditions and use a modern flue gas cleaning technique. This will result in a total reduction of the emission levels by a factor of 100-1000, resulting in an environmental sound method for refuse disposal. 101 refs