Long-term assessment of waste management options--a new, integrated and goal-oriented approach.

Selected waste management scenarios were evaluated with regard to the goals of the Austrian Waste Management Act, taking into account long-term environmental protection and resource conservation as well as costs. Municipal solid waste (MSW) and sewage sludge have been chosen as the system inputs. The scenarios were compared to the status-quo scenario by combining Material Flow Analysis (MFA) and economic evaluation methods. Both, welfare-oriented Cost-Benefit Analysis (CBA) and Modified Cost-Effectiveness Analysis (MCEA) were applied for this assessment. Unlike CBA, MCEA takes into consideration long-term impacts of landfilled material in non-monetary terms. The results of the CBA correspond to those of the MCEA. Both evaluation methods confirm: If long-term effects are taken into account with the same weight irrespective of when they occur, the Austrian goals of waste management are reached more efficiently by thermal waste treatment scenarios than by mechanical-biological treatment scenarios or by landfilling without pre-treatment.

4-Nonylphenol in sewage sludge: accumulation of toxic metabolites from nonionic surfactants.

Anaerobically treated sewage sludge was found to contain extraordinarily high concentrations of 4-nonylphenol, a metabolite derived from nonionic surfactants of the nonylphenol polyethoxylate type. Concentrations in activated sewage sludge, in mixed primary and secondary sludge, and in aerobically stabilized sludge were substantially lower, suggesting that the formation of 4-nonylphenol is favored under mesophilic anaerobic conditions. Because 4-nonylphenol may be highly toxic to aquatic life, further research is needed on the fate of 4-nonylphenol after sludge is disposed of in the environment.

Waste-related cadmium cycle in Switzerland.

The anthropogenic contribution to the global cadmium flux exceeds natural sources by a factor of three. The most important pathway is the atmosphere; therefore, high cadmium concentrations can be found even in remote areas. On a local level, the increase in cadmium consumption can be observed in increasing concentrations in the soil, plants, and food. The question arises as to what extent the soil-plant-man-waste-soil cycle can be loaded with cadmium in order to function without negative impact on the environment. In Switzerland, 120 tons (t) of cadmium are consumed per year. Of this amount, 25 t end up in municipal solid waste, 3 t in wastewater, and 19 t in precipitation and dry fallout. As a consequence of today's waste management practice (75% incineration, 20% sanitary landfill, 5% composting; 75% of all sewage is purified), the annual input to the soil is 40 t: 18 t concentrated in landfills, 19 t dissipated via the atmosphere, and 3 t directly spread via sewage sludge, compost, and fertilizer on agricultural land. If even distribution were possible, the cadmium content of the soil would theoretically double in 150 years. The accumulation in the soil will increase the cadmium content of plants grown on such a soil. According to a simple model, the level of 3 ppm cadmium in soils should not be surpassed. At such concentrations, plants are likely to contain greater than 0.4 mg Cd/kg, a concentration which can cause toxic effects in long-term experiments. The safe level in food might be even lower. In reality, cadmium is not evenly distributed over Switzerland. According to today's practice, it must be assumed that in only 14 years the use of compost will have enriched soils to such an extent that its cadmium content will prohibit the production of food for human consumption. For sewage sludge, this timespan is 130 years. If heavy metal limits in food are to be observed, the input of such metals to the soil has to be limited. In a steady state, the cadmium input to the soil should be equal to its output via plants, leachate, and erosion. This implies that today's dissipative use of cadmium must be stopped.

Tendencias en sistemas de evacuacion de desechos solidos: relaciones entre desechos solidos, liquidos y gaseosos. / Trends of solid-water disposal systems: relationship between solid, liquid and gaseous wastes

Se analizan los peligros que representan los desechos para la salud publica y los problemas que plantea su evacuacion debido a la contaminacion del medio ambiente que puede provocar. Tambien se estudia el nuevo enfoque que se da a la evacuacion de desechos considerada no como un elemento aislado, sino formando parte de un conjunto de factores interrelacionados a los que se da la denominacion comun de gestion de desechos