Odor composition analysis and odor indicator selection during sewage sludge composting

Abstract

On the basis of total temperature increase, normal dehydration, and maturity, the odor compositions of surface and internal piles in a well-run sewage sludge compost plant were analyzed using gas chromatography–mass spectrometry with a liquid nitrogen cooling system and a portable odor detector. Approximately 80 types of substances were detected, including 2 volatile inorganic compounds, 4 sulfur organic compounds, 16 benzenes, 27 alkanes, 15 alkenes, and 19 halogenated compounds. Most pollutants were mainly produced in the mesophilic and pre-thermophilic periods. The sulfur volatile organic compounds contributed significantly to odor and should be controlled primarily. Treatment strategies should be based on the properties of sulfur organic compounds. Hydrogen sulfide, methyl mercaptan, dimethyl disulfide, dimethyl sulfide, ammonia, and carbon disulfide were selected as core indicators. Ammonia, hydrogen sulfide, carbon disulfide, dimethyl disulfide, methyl mercaptan, dimethylbenzene, phenylpropane, and isopentane were designated as concentration indicators. Benzene, m-xylene, p-xylene, dimethylbenzene, dichloromethane, toluene, chlorobenzene, trichloromethane, carbon tetrachloride, and ethylbenzene were selected as health indicators. According to the principle of odor pollution indicator selection, dimethyl disulfide was selected as an odor pollution indicator of sewage sludge composting. Monitoring dimethyl disulfide provides a highly scientific method for modeling and evaluating odor pollution from sewage sludge composting facilities. Implications: Composting is one of the most important methods for sewage sludge treatment and improving the low organic matter content of many agricultural soils. However, odors are inevitably produced during the composting process. Understanding the production and emission patterns of odors is important for odor control and treatment. Core indicators, concentration indicators, and health indicators provide an index system to odor evaluation. An odor pollution indicator provides theoretical support for further modelling and evaluating odor pollution from sewage sludge composting facilities.

Heat Energy and Gas Emissions during Composting of Sewage Sludge

“…The exact composition of the mixture was slightly different than in these studies-in addition to 35% sawdust, there was still 5% straw, but also a 45% higher total weight and air-flow that was over 20% greater (which had a detrimental effect on the release of ammonia). Other studies have also shown high ammonia emissions during high temperatures, while the peak of NH 3 emissions coincided with the maximum temperature and oxygen uptake rate [48,[61][62][63].…”

“…Energies 2020, 13, x FOR PEER REVIEW 8 of 13 total weight and air-flow that was over 20% greater (which had a detrimental effect on the release of ammonia). Other studies have also shown high ammonia emissions during high temperatures, while the peak of NH3 emissions coincided with the maximum temperature and oxygen uptake rate [48,[61][62][63]. However, for a better comparison of ammonia losses, it was decided that we would calculate NH3 emission from 1 kg of sewage sludge that was initially used for composting (ammonia emission from straw was negligible).…”

Oxygen Monitoring Equipment for Sewage-Sludge Composting and Its Application to Aeration Optimization

“…Composting is a complex biochemical process, wherein the components of produced gases are complicated, and predominantly include ammonia, hydrogen sulfide, and water, as well as mercaptan and thioether [ 32 ]. To ensure the measurement accuracy of the oxygen-monitoring equipment, it was placed in a gas environment with ammonia, hydrogen sulfide, and water.…”

Odour Nuisance As a Consequence of Preparation for Circular Economy

“…Due to population density, location and concentration of odour sources and the number of affected individuals, the problem of nuisance mainly concerns urban areas (Pedersen, 2015). Watercourses (Sado-Inamura and Fukushi, 2018) and urban sewerage (García et al, 2017;Zhu et al, 2016) are important sources of urban fragrances. These sources are the subject of studies not only on the chemical composition of liquids but also on the composition of odour emitted by them (Zhu et al, 2016).…”

“…Watercourses (Sado-Inamura and Fukushi, 2018) and urban sewerage (García et al, 2017;Zhu et al, 2016) are important sources of urban fragrances. These sources are the subject of studies not only on the chemical composition of liquids but also on the composition of odour emitted by them (Zhu et al, 2016). Additional sources of smell in urban areas are increasingly being fumes (Cernansky, 1983), biomass (Freiberg et al, 2018) or fragrances from closed surface equipment, such as offices, which may affect the quality of work and health of employees (Wypych, 2017), and fragrances from landfills or composting plants.…”