Exposure to bioaerosols and noise at a Finnish dry waste treatment plant.

Repeated measurements were carried out during two different campaigns between 1998 and 2001 to assess the occupational hygiene at a Finnish dry waste treatment plant. The analytical determinations were done in four different places within the processing hall of the plant: near a conveyor belt, near a jigger screen, near an after-crusher and near a bailer. Measurements were also carried out in a coffee room for employees. Concentrations of bacteria, fungi and actinomycetes were determined by two methods (six-stage impactor and Camnea method) and levels of endotoxins, dust and noise were also investigated. High concentrations of microbes and endotoxins and the noise level were found to be a real problem in the waste processing hall. Microbe concentrations were highest during management of the dry waste fraction. Endotoxin concentrations all exceeded the threshold value of 200 EU m(-3) irrespective of the measurement place, with the only exception near the after-crusher where the average concentration was always as low as 60 EU m(-3). The noise level exceeded the Finnish threshold value of 85 dBA. Problems were not easily solved through technical modifications and more radical improvements are needed. Improvements in reliability are also required in the measuring methods before their application in waste treatment plants. In particular, a new method of dust collection is recommended.     

Occupational hygiene in a Finnish drum composting plant

Bioaerosols (microbes, dust and endotoxins) and volatile organic compounds (VOCs) were determined in the working air of a drum composting plant treating source-separated catering waste. Different composting activities at the Oulu drum composting plant take place in their own units separated by modular design and constructions. Important implication of this is that the control room is a relatively clean working environment and the risk of exposure to harmful factors is low. However, the number of viable airborne microbes was high both in the biowaste receiving hall and in the drum composting hall. The concentration (geometric average) of total microbes was 21.8 million pcs/m3 in the biowaste receiving hall, 13.9 million pcs/m3 in the drum composting hall, and just 1.4 million pcs/m3 in the control room. Endotoxin concentrations were high in the biowaste receiving hall and in the drum composting hall. The average (arithmetic) endotoxin concentration was over the threshold value of 200 EU/m3 in both measurement locations. In all working areas, the average (arithmetic) dust concentrations were in a low range of 0.6-0.7 mg/m3, being below the Finnish threshold value of 5 mg/m3. In the receiving hall and drum composting hall, the concentrations of airborne microbes and endotoxins may rise to levels hazardous to health during prolonged exposure. It is advisable to use a respirator mask (class P3) in these areas. Detected volatile organic compounds were typical compounds of composting plants: carboxylic acids and their esters, alcohols, ketones, aldehydes, and terpenes. Concentrations of VOCs were much lower than the Finnish threshold limit values (Finnish TLVs), many of the quantified compounds exceeded their threshold odour concentrations (TOCs). Primary health effects due VOCs were not presumable at these concentrations but unpleasant odours may cause secondary symptoms such as nausea and hypersensitivity reactions. This situation is typical of composting plants where the workers are exposed to dozens of VOCs simultaneously. The odour units (OU/m3) were measured using olfactometer. The numbers were 23,000 OU/m3 at the output end of the composting drum and 6300 OU/m3 in the exhaust pipe. Inside the composting hall, the number of odour units was 500 and 560 OU/m3.     

Occupational hygiene in a waste incineration plant

The Turku incineration plant was renovated in 1995 to meet the emission requirements of modern waste combustion facilities. It treats presorted municipal waste from 170,000 residents in the Turku area. In the plant, the incineration process produces several types of by-products having importance in terms of occupational hygiene. Although not obligated by the law, the management of the plant has a keen interest in occupational hygiene at the plant, which was studied from 1998 to 2001. Concentrations of microbes, endotoxins, and dust and the noise level were investigated in three different working areas. Microbe measurements were conducted with a six-stage impactor and using the CAMNEA method. Especially in the measurements of viable fungi and actinomycetes, the six-stage impactor gave better results than the CAMNEA method. Concentrations of bio-aerosols and the level of noise were high enough in the waste bunker to be occasionally harmful to the health of employees. The endotoxin concentration could also be harmful to health in the combustion area, and the noise level there exceeded the Finnish threshold value of 85dBA. The total number of microbes (viable+dead) was high in a few measurements in the crane room. One reason for these high numbers was prior moisture damage, which was repaired in 2000. The use of ear protectors is advised in the bunker area and in the combustion area. Use of respirators (class P3) is advised in the bunker area to prevent the exposure of employees to bio-aerosols.     

Occupational hygiene in terms of volatile organic compounds (VOCs) and bioaerosols at two solid waste management plants in Finland

Factors affecting occupational hygiene were measured at the solid waste transferring plant at Hyvinkää and at the optic separation plant in Hämeenlinna. Measurements consisted of volatile organic compounds (VOCs) and bioaerosols including microbes, dust and endotoxins.The most abundant compounds in both of the plants were aliphatic and aromatic hydrocarbons, esters of carboxylic acids, ketones and terpenes. In terms of odour generation, the most important emissions were acetic acid, 2,3-butanedione, ethyl acetate, alpha-pinene and limonene due to their low threshold odour concentrations. At the optic waste separation plant, limonene occurred at the highest concentration of all single compounds of identified VOCs. The concentration of any single volatile organic compound did not exceed the occupational exposure limit (OEL) concentration. However, 2,3-butanedione as a health risk compound is discussed based on recent scientific findings linking it to lung disease.Microbe and dust concentrations were low at the waste transferring plant. Only endotoxin concentrations may cause health problems; the average concentration inside the plant was 425 EU/m³ which clearly exceeded the threshold value of 90 EU/m³. In the wheel loader cabin the endotoxin concentrations were below 1 EU/m³. High microbial and endotoxin concentrations were measured in the processing hall at the optic waste separation plant. The average concentration of endotoxins was found to be 10,980 EU/m³, a concentration which may cause health risks. Concentrations of viable fungi were quite high in few measurements in the control room. The most problematic factor was endotoxins whose average measured concentrations was 4853 EU/m³.     

家用厨余垃圾处理机关键零部件结构设计及有限元分析

在现有厨余垃圾粉碎直排工艺上进行改进,变为将日常餐厨垃圾粉碎、脱水、收集的处理流程,达到避免环境污染和资源二次利用的目的。基于厨余垃圾各个组分的特性分析,以模塑螺旋挤出压缩和压榨固液分离的原理为指导,对变螺距变轴径特制螺杆的结构进行设计。基于有限元方法对变径变距螺杆进行了刚度、强度、循环寿命以及模态振动分析,仿真结果表明均达到设计要求。对设计模型进行实物加工并开展实验论证,对厨余垃圾组成种类进行分析并进行单因素破碎实验,七类厨余垃圾能得到有效破碎,处理产物粒度在2~3 mm,达到预期期望;对常规混合状态厨余垃圾以梯度体积进行分组验证日常实际处理情况,处理结果表明,脱水率达到51%,体积缩减率达75%,餐厨垃圾处理的实用性得以保证。     

Airborne contaminants at waste treatment plants

Airborne contaminants in Finnish waste treatment plants were studied at two plants using mainly manual sorting and one incineration plant. Air samples were analysed for mesophilic and thermotolerant bacteria, mesophilic fungi, endotoxin, dust and heavy metals (lead, cadmium). The concentrations of mesophilic bacteria in the working air of the waste treatment plants were under 2 × 10⁴ colony forming units (cfu) m⁻³ and the concentrations of mesophilic fungi were under 7 × 10⁴ cfu m⁻³. There was no seasonal variation in the concentrations of bacteria, but the concentrations of fungi were highest in autumn at the waste incineration plant. The concentrations of microbes recorded with two sampling methods, the Andersen and Nuclepore filter methods, differed but were usually of the same order of magnitude. The identified bacteria did not include any potent pathogens. In manual sorting the level of organic dust reached 38 mg m⁻³, whereas the 8-h hygiene limit value for organic dust is 5mg m⁻³ and the 15-min hygiene limit value is 10 mg m⁻³. The endotoxin levels were all below 30 ng m⁻³ and the concentrations of heavy metals were low.     

厨余垃圾-蔬菜废物协同生产液肥项目技术经济分析

厨余垃圾-蔬菜废物协同生产液肥项目,需要建立科学、高效的运行管理机制和投入产出机制,以提高其经济效益。系统研究银川市某液肥项目的设备投资和运行费用等情况,目前该项目处理规模约为10.6 t/d,运行负荷率为35.3%,导致处理成本高达337.9元/t。因此,提高运行负荷率,是降低处理成本的关键。     

餐厨废弃油脂处理管理和资源化利用探讨

“地沟油”的不当处理不仅影响城市水环境,而且威胁着人们的身体健康。餐厨废弃油脂的管理已经成为广受关注的食品安全的重大问题。介绍了餐厨废弃油脂处理管理的重要意义,并对上海的管理实践和经验进行了分析总结,提出了对餐厨废弃油脂回收处理管理和资源化利用的若干建议。     

Report: transboundary hazardous waste management. part II: performance auditing of treatment facilities in importing countries.

Before implementing the self-monitoring model programme of the Basel Convention in the Asia, Taiwan has conducted a comprehensive 4-year follow-up project to visit the governmental authorities and waste-disposal facilities in the countries that import waste from Taiwan. A total of nine treatment facilities, six of which are reported in this paper, and the five countries where the plants are located were visited in 2001-2002. France, Belgium and Finland primarily handled polychlorinated biphenyl capacitors, steel mill dust and metal waste. The United States accepted metal sludge, mainly electroplating sludge, from Taiwan. Waste printed circuit boards, waste wires and cables, and a mixture of waste metals and electronics were the major items exported to China. Relatively speaking, most treatment plants for hazardous waste paid close attention to environmental management, such as pollution control and monitoring, site zoning, system management regarding occupational safety and hygiene, data management, permits application, and image promotion. Under the tight restrictions formulated by the central environment agency, waste treatment plants in China managed the environmental issues seriously. For example, one of the treatment plants had ISO 14001 certification. It is believed that with continuous implementation of regulations, more improvement is foreseeable. Meanwhile, Taiwan and China should also continuously enhance their collaboration regarding the transboundary management of hazardous waste.     

Work safety in waste treatment

Accident risks in waste treatment were studied at five sanitary landfills, two plants using mainly manual sorting and one incineration plant in southern Finland. Work hazards were detected by means of safety analysis. In addition, accident statistics were used. Work safety problems were found at all work stages. At the sanitary landfills, the major safety problems were posed by operation of the compactor or other machinery and by hazardous wastes. In waste sorting, common problems are odour and dust, lacerations and back injuries. Falling into the waste compactor or paper silos may cause fatal injury and its probability was also high. The highest noise level measured was 97 dB(A). In waste incineration, the most serious hazards were caused by fires, clogging of the funnels and cleaning of the grate. Most deficiencies in work safety can be remedied at a moderate price. The corrective measures involve technical solutions, working methods, supervision, training and occupational health services. The accident rates for workers in the four waste treatment plants were slightly lower than the average for industry.     

Revegetating industrial waste disposal sites

Short-rotation tree plantations were established at seven industrial waste disposal sites in southern Finland. Altogether 31,500 willow cuttings were planted between 1984 and 1989. Neutralized residue from a titanium dioxide pigment process had an unfavourable influence on growth. Biological sludges from a municipal sewage treatment plant, and pulp and paper mills were too compact to be used alone as substrate, but gave a good supply of nutrients. Sand, bark and de-inking waste were sufficiently porous, but were low in nutrients. A mixture of different waste materials is therefore recommended as a substrate for willow stands. Replacement of a natural soil cover with waste material allows disposal of a greater volume of refuse and diminishes the costs of revegetation. The landfill characteristics have to be taken into account. The high temperature of bark also disturbed the growth of willow stands. Ferrous sulphate in the landfill limits the possibility of irrigating the stand. The highest biomass production of the stands exceeded that of normal Finnish forest. Willow stands can be used for landscaping industrial waste disposal sites, for increasing evapotranspiration and minimizing leachate discharge.     

Occupational health problems due to garbage sorting

Medical examinations and dust analysis showed that illness of workers, predominently asthma, in an enclosed waste sorting plant in Denmark, was probably related to high particulate levels containing bacteria and endotoxins derived from decaying waste. Modification of the plant to enclose conveyors and install vacuum cleaning systems to reduce dust levels led to significant reductions in airborne bacteria and the nearly complete elimination of endotoxins. However, fungi concentrations were not reduced.     

Current EU-27 technical potential of organic waste streams for biogas and energy production

Anaerobic digestion of organic waste generated by households, businesses, agriculture, and industry is an important approach as method of waste treatment – especially with regard to its potential as an alternative energy source and its cost-effectiveness. Separate collection of biowaste from households or vegetal waste from public green spaces is already established in some EU-27 countries. The material recovery in composting plants is common for biowaste and vegetal waste. Brewery waste fractions generated by beer production are often used for animal feeding after a suitable preparation. Waste streams from paper industry generated by pulp and paper production such as black liquor or paper sludge are often highly contaminated with toxic substances. Recovery of chemicals and the use in thermal processes like incineration, pyrolysis, and gasification are typical utilization paths. The current utilization of organic waste from households and institutions (without agricultural waste) was investigated for EU-27 countries with Germany as an in-depth example. Besides of biowaste little is known about the suitability of waste streams from brewery and paper industry for anaerobic digestion. Therefore, an evaluation of the most important biogas process parameters for different substrates was carried out, in order to calculate the biogas utilization potential of these waste quantities. Furthermore, a calculation of biogas energy potentials was carried out for defined waste fractions which are most suitable for anaerobic digestion. Up to 1% of the primary energy demand can be covered by the calculated total biogas energy potential. By using a “best-practice-scenario” for separately collected biowaste, the coverage of primary energy demand may be increased above 2% for several countries. By using sector-specific waste streams, for example the German paper industry could cover up to 4.7% and the German brewery industry up to 71.2% of its total energy demand.     

发挥供销系统网络优势 延伸餐厨废弃物资源利用的思考

对处于国家中心城市地位的广州来说,随着城市人口、经济社会不断发展,尤其随着餐饮行业的蓬勃发展,日产餐厨废弃物近1万t,如不妥善合理处理,将对城市环境和城市管理造成极大压力。无论是焚烧、填埋、还是生化处理模式,餐厨废弃物资源化处理后产品的出路都没有得到有效解决。广州供销社系统在产业链后端延伸方面具有我国任何社会组织无法比拟的优势,是解决餐厨废弃物资源化产品深加工出路的重要力量。除了发挥供销社网络优势外,仍需要政府在政策、土地、资金等方面的大力支持,共同推进,才能实现餐厨废弃物"由餐桌中来,加工调制后再到农田中去,生产出来的有机食品再回到餐桌"的真正循环。     

Attitude towards the incorporation of the selective collection of biowaste in a municipal solid waste management system. A case study

European waste legislation has been encouraging for years the incorporation of selective collection systems for the biowaste fraction. European countries are therefore incorporating it into their current municipal solid waste management (MSWM) systems. However, this incorporation involves changes in the current waste management habits of households. In this paper, the attitude of the public towards the incorporation of selective collection of biowaste into an existing MSWM system in a Spanish municipality is analysed. A semi-structured telephone interview was used to obtain information regarding aspects such as: level of participation in current waste collection systems, willingness to participate in selective collection of biowaste, reasons and barriers that affect participation, willingness to pay for the incorporation of the selective collection of biowaste and the socioeconomic characteristics of citizens who are willing to participate and pay for selective collection of biowaste. The results showed that approximately 81% of the respondents were willing to participate in selective collection of biowaste. This percentage would increase until 89% if the Town Council provided specific waste bins and bags, since the main barrier to participate in the new selective collection system is the need to use specific waste bin and bags for the separation of biowaste. A logit response model was applied to estimate the average willingness to pay, obtaining an estimated mean of 7.5% on top of the current waste management annual tax. The relationship of willingness to participate and willingness to pay for the implementation of this new selective collection with the socioeconomic variables (age, gender, size of the household, work, education and income) was analysed. Chi-square independence tests and binary logistic regression was used for willingness to participate, not being obtained any significant relationship. Chi-square independence tests, ordinal logistic regression and ordinary linear regression was applied for willingness to pay, obtaining statistically significant relationship for most of the socioeconomic variables.     

RECOMMENDATIONS FOR THE MANAGEMENT OF WASTES FROM HEALTHCARE FACILITIES IN HELSINKI

In Helsinki, Finland, new guidelines have been adopted for the management of wastes from healthcare facilities. The purpose has been to rationalize waste management, reducing the amount of waste needing special treatment and lowering costs, while at the same time maintaining occupational safety and preventing environmental hazards. The changes are mainly due to the new definition of infectious waste, based on practical assessment of the possibility of spread of infection via the wastes. As a result, it has been possible to omit one chain of waste handling which has led to simpler practices and economic benefits. Sanitary landfill has been accepted for disposal of clinical waste, except for the biological waste to be incinerated for ethical reasons and infectious waste contaminated by class 4 viruses,Yersinia pestisorBacillus anthracis. Diseases caused by these micro-organisms are not a practical problem in Finland.     

管桩余浆的合理开发利用

对管桩余浆常用的几种回收利用方法作了分析对比,提出了较为完善的余浆干法利用方法,将余浆固化后经破碎、烘干、粉磨,再用作混凝土的掺合料,更加有利于发挥余浆的潜在活性.     

Mass balance to assess the efficiency of a mechanical-biological treatment

Using mechanical-biological treatment of residual municipal solid waste, it is possible to significantly lower landfill volume and gas and leachate emissions. Moreover, the landfill characteristics are improved. The performance of the Mende (France) mechanical-biological treatment plant is assessed via mass balances coupled with manual sorting according to the MODECOMtrade mark methodology and biochemical methane potential after 90 days of incubation. The site includes mechanical sorting operations, a rotary sequential bioreactor, controlled aerobic stabilisation corridors, maturation platforms, and a sanitary landfill site for waste disposal in separated cells. Results showed that several steps could be improved: after a first sieving step, about 12% of the potentially biodegradable matter is landfilled directly without any treatment; mechanical disintegration of papers and cardboards in the rotary sequential bioreactor is insufficient and leads to a high proportion of papers and cardboards being landfilled without further treatment. Two fine fractions go through stabilisation and maturation steps. At the end of the maturation step, about 54% of the potentially biodegradable matter is degraded. The biochemical methane potential after 90 days of incubation is reduced by 81% for one of the two fine fractions and reduced by 88% for the other one. Considering the whole plant, there is a reduction of nearly 20% DM of the entering residual municipal solid waste.     

Characterization of household waste in Greenland

The composition of household waste in Greenland was investigated for the first time. About 2 tonnes of household waste was sampled as every 7th bag collected during 1 week along the scheduled collection routes in Sisimiut, the second largest town in Greenland with about 5400 inhabitants. The collection bags were sorted manually into 10 material fractions. The household waste composition consisted primarily of biowaste (43%) and the combustible fraction (30%), including anything combustible that did not belong to other clean fractions as paper, cardboard and plastic. Paper (8%) (dominated by magazine type paper) and glass (7%) were other important material fractions of the household waste. The remaining approximately 10% constituted of steel (1.5%), aluminum (0.5%), plastic (2.4%), wood (1.0%), non-combustible waste (1.8%) and household hazardous waste (1.2%). The high content of biowaste and the low content of paper make Greenlandic waste much different from Danish household waste. The moisture content, calorific value and chemical composition (55 elements, of which 22 were below detection limits) were determined for each material fraction. These characteristics were similar to what has been found for material fractions in Danish household waste. The chemical composition and the calorific value of the plastic fraction revealed that this fraction was not clean but contained a lot of biowaste. The established waste composition is useful in assessing alternative waste management schemes for household waste in Greenland.     

In situ ammonia removal in bioreactor landfill leachate

Although bioreactor landfills have many advantages associated with them, challenges remain, including the persistence of NH(3)-N in the leachate. Because NH(3)-N is both persistent and toxic, it will likely influence when the landfill is biologically stable and when post-closure monitoring may end. An in situ nitrogen removal technique would be advantageous. Recent studies have shown the efficacy of such processes; however, they are lacking the data required to enable adequate implementation at field-scale bioreactor landfills. Research was conducted to evaluate the kinetics of in situ ammonia removal in both acclimated and unacclimated wastes to aid in developing guidance for field-scale implementation. Results demonstrate that in situ nitrification is feasible in an aerated solid waste environment and that the potential for simultaneous nitrification and denitrification (even under low biodegradable C:N conditions) in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas. All rate data fit well to Monod kinetics, with specific rates of removal of 0.196 and 0.117 mgN/day-g dry waste and half-saturation constants of 59.6 and 147 mgN/L for acclimated and unacclimated wastes, respectively. Although specific rates of ammonia removal in the unacclimated waste are lower than in the acclimated waste, a relatively quick start-up of ammonia removal was observed in the unacclimated waste. Using the removal rate expressions developed will allow for estimation of the treatment times and volumes necessary to remove NH(3)-N from recirculated landfill leachate.