Municipal Biowaste Research Articles

(M)VOC and composting facilities. Part 1: (M)VOC emissions from municipal biowaste and plant refuse.

Malodorous volatiles derived from the decomposition of biowaste within the process of composting might pose a risk to human health. Different techniques of process engineering have been developed to minimise the burden of malodorous compounds in air possibly affecting compost workers and residents in the vicinity. In the present study, three different composting facilities were examined for the emission of volatiles to estimate the impact of process engineering on the dispersal of odorous compounds and to discuss its relevance for human health. Concentrations of single compounds belonging to alcohols, ketones, furanes, sulfur-containing compounds and especially terpenes ranged from 10(2) up to nearly 10(6) ng/m3 depending on the sampling sites and the process engineering. The ratio of MVOC and total VOC measured changed throughout the process of biodegradation. A certain combination of volatile compounds coincided with the occurrence of typical compost odour. The type of process engineering seemed to have a major impact on the emission of volatiles, as amounts of (microbial) volatiles emitted were characteristic for the different techniques used. Thus, the MVOC emission basically depends on the degree of biodegradation. It is likely that the concentrations workers are exposed to can have an impact on human health. It is obvious that less sophisticated types of process engineering give rise to greater amounts of bioaerosols and volatiles and, therefore, technical devices have to be improved and controlled regularly to minimise adverse health effects on workers.

Mineralization, metabolism and formation of non-extractable residues of 14C-labelled organic contaminants during pilot-scale composting of municipal biowaste

Use of municipal biowaste for composting instead of its disposal has become a major source of concern as regards contamination by hazardous substances. To elucidate the hazard potential of compost application, municipal biowaste was amended with 14C-labelled model substances (pyrene, simazine) and incubated in a pilot-scale composting simulation system. A mass balance incorporating the mineralization, metabolism and sorption of the two model substances was established over a period of 370 days. The results are quite different for the two chemicals, reflecting their intrinsic properties: more than 60% of the applied 14C-simazine resulted in non-extractable residues (NER). Silylation experiments indicated that the formation of NER from simazine and its metabolites was due to both physical entrapment in the matrix and chemical binding. The mineralization and formation of NER represented the major pathways of disappearance for pyrene during one year of composting, accounting for 60 and 26% of initially applied 14C-activity, respectively. Mineralization occurred delayed after the thermophilic phase. As regards remobilization, release of pyrene from NER during composting could be excluded, whereas simazine, data were inconclusive in this respect.

Transformation of dissolved organic matter (DOM) and 14C-labelled organic contaminants during composting of municipal biowaste

Composting of municipal biowaste in the presence of 14C-labelled organic contaminants was studied in an attempt to characterize the mobilization potential of dissolved organic matter (DOM) for hydrophobic contaminants. The properties and transformation of DOM extracted from municipal biowaste compost with 10 mM KCl at six stages during 370 days of composting were investigated. DOM was fractionated into molecular weight fractions by ultrafiltration, and DOM structure was studied using CPMAS 13C-NMR- and UV-spectroscopy. The distribution of 14C-labelled model substances (DEHP, pyrene, simazine) upon molecular weight fractions was investigated by ultrafiltration, and association to DOM was studied performing flocculation experiments. The binding capacity of DOM for the model substances was of secondary influence for the mobilization because the intense biochemical reactions during composting pre-dominated the fate of the substances. Composting favoured the degradation of model substances to polar metabolites and supported their binding to the DOM matrix. DEHP and simazine were mainly found in the low- to medium-molecular DOM fraction and showed a small amount of DOM-associated radioactivity (approx. 10%). Pyrene and its metabolites had high affinities to high-molecular DOM. However, a direct relationship between DOM-quality and enhancement of pyrene solubility was not visible. After 120 days of composting DOM showed the highest binding capacity for hydrophobic contaminants.

Cobiogasification of Wastepaper Products with Separately Collected Municipal Solid Waste

▪ The treatment of soiled hygiene papers (HYP), such as diapers and sanitary napkins, added at a concentration of 10 percent (w/w) to separately collected municipal biowaste was tested at Biotechnishce Abfallverwertung (BTA)'s three stage mesophilic biogas plant in Munich. The study aimed to establish the feasibility of cobiogasification of hygiene papers and biowaste. Parameters measured were: Efficiency of plastics and inerts separation; Mass balances; Organic and inorganic dry residues; COD; C:N ratio; Heavy metal content; Bacterial counts; Fiber analysis of suspension; Residues; Effluent for hemicellulose, cellulose and lignin; Biogas yield; and Quality. In the conditioning stage, the hygiene papers (HYP) (10 percent) were completely suspended with municipal solid waste. The dry materials balance of the conditioning unit resulted in an increase of 1.5 percent of the screenings, corresponding exactly to the amount of the added plastics. Heavy metal contents in the residues were well below limits establ...