Anja Veijanen

Analysis of odour and taste problems in high-density polyethene

The compounds that cause off-flavours in plastics, have been recognized mainly as carbonyl compounds (aldehydes, ketones and esters). They occur in low concentrations, and due to their low-threshold odour concentrations, their typical odours were identified. Most of these off-flavour compounds are volatile. Chemical analysis of smelling compounds requires a very sensitive method with a high-resolution capability. The analysis of volatile organic compounds (VOCs) in high density polyethene (HD-PE) granules and waters in which the granules have been shaken for 4 h, were carried out by gas chromatography-mass spectrometry-sniffing system (GC-MS-SNIFF) and by gas chromatography-fourier transform infrared spectroscopy-sniffing system (GC-FTIR-SNIFF). A purge-and-trap technique was used to introduce the VOCs from samples into the gas chromatograph. Leaching waters of HD-PE granules were also evaluated by panel. This panel agreed upon six descriptive attributes for odour: sweet, chemical, stale, dusty, foul and floor-cloth. The attributes for taste were: sweet, metallic, stony, pungent, dusty, plastic, foul, stink bug and candle grease.

Occupational hygiene in biowaste composting

Source-separated biowastes from the Helsinki Metropolitan Area have been composted in open air windrows at Ammas suo, the Helsinki regional landfill in Espoo (Finland). The most significant problem encountered in the early stages of the process has been the formation of rancid odor causing human discomfort. The offensive odor was mainly due to car boxylic acids. A total of 110 organic compounds were detected in volatile emissions from windrow composts with an integrated sensory and instrumental method. Occasionally the temperatures in the windrows exceeded 80°C. Bacterial measurements also revealed substantial populations of bacte ria at 75°C. The concentrations of airborne microbes and endotoxins were highest during the crushing of fresh biowaste and the turning of compost, and were relatively high in sum mer and when windrows were dry. The most common fungi in the air were Aspergillus and Penicillium. Dust concentrations were consistently low. The concentrations of microbes were never so high as to constitute an acute health hazard from the occasional exposure. Continuous exposure to such concen trations nevertheless increases the risk of illness. The time, neccessary for the compost to become hygienic improved from four months to four weeks during the project. Drum composting was also tested and was found to be an alternative approach to treating organic wastes. Emissions from the drum composting were low compared to open air composting.

Effect of in situ composting on reducing offensive odors and volatile organic compounds in swineries.

Seven swine farms were studied to find out how the in situ composting system, compared to the slatted floor pit system, influences the concentration and occurrence of malodorous compounds. Ammonia concentrations were measured with diffusion tubes. Small molecular sulfur compounds were analyzed using laminated bags and a gas chromatograph with a FP-detector. All other volatile organic compounds were analyzed by gas chromatography/mass spectrometry with simultaneous sniffing of the eluted compounds. About 400 organic compounds were identified from the air samples, and 94 suspect odorous compounds are listed in the present article. The most intense and unpleasant odors were caused by p-cresol, carboxylic acids (C2-C7), and some ketones such as 3-hydroxy-2-butanone, 2,3-butanedione, and 2-butanone. Terpenes (alpha-pinene, beta-pinene, 3-carene, and limonene), which originate from sawdust, caused the main peaks in the chromatograms of compost swineries. In swine confinement buildings where the composting system was functioning properly, the concentration of sulfur compounds, and especially of carboxylic acids, ketones, and p-cresol, fell effectively. The use of sawdust as composting material caused elevated concentrations of terpenes in the ambient air. There was clearly less airborne ammonia and hydrogen sulfide in the well-functioning compost swineries than in the poorly functioning ones. Elevated hydrogen sulfide levels were measured during turning work, however. In one composting swinery, the hydrogen sulfide level was as high as 15 mg/m3 during turning work. All the other concentrations of odorous compounds did not exceed occupational exposure limit values, but several compounds exceeded the respective threshold odor concentrations.

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/m(3) which clearly exceeded the threshold value of 90 EU/m(3). In the wheel loader cabin the endotoxin concentrations were below 1 EU/m(3). 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/m(3), 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/m(3).

Chlorinated short chain aliphatic hydrocarbons in pine needles by purge and trap gas chromatography/mass spectrometry

The concentrations of volatile chlorinated short chain aliphatic hydrocarbons in pine needles have been measured using purge and trap GC/MS. The concentrations of dichloromethane, chloroform, dichloroethene and tetrachloroethene in the needles were calculated. The concentrations of dichloromethane and tetrachloroethene were highest. As a rule the concentrations were higher in the older needles. The needle samples were collected from five sampling points in an area situated in the Southern Finland in the vicinity of a metal scrab plant. Reference needles were collected in the Central Finland. Needles originated from years 1991, 1992 and 1993.