Distribution and sensorial relevance of volatile organic compounds emitted throughout wastewater biosolids processing.

A diverse range of volatile organic compounds (VOCs) are emitted from wastewater biosolids processing. Odorous emissions are predominately made up of volatile sulfur compounds (VSCs) which are typically the only odorants measured. However, a range of VOCs are known to contribute to malodours yet previous studies often overlook the contribution of VOCs in comparison with VSCs.

Influence of the fetch parameter on results from empirical correlations for estimating odorous emissions at passive liquid surfaces.

Passive liquid surfaces in wastewater treatment plants may be potential sources of odorous emissions. This study investigates the occurrence and significance of deviations that may originate from the use of the effective diameter as fetch parameter in the empirical correlations utilised by the WATER9 model to estimate odorous emissions at passive liquid surfaces. A sensitivity analysis was performed using benzene as a model compound and considering representative conditions of wind speed and wind alignment.

Prioritisation of odorants emitted from sewers using odour activity values.

Volatile sulfur and volatile organic compound (VSC and VOC, respectively) emissions were measured over a 3.5 year period from 21 field monitoring sites across Australia to determine their potential contribution to sewer odours and support the evaluation of odour abatement processes used to treat sewer emissions. Measured VOC concentrations were generally less than 250 μg/m(3), although some VOCs (toluene, trimethylbenzene and cymene) were present at higher concentrations.

Reduced sulfur compounds in the atmosphere of sewer networks in Australia: geographic (and seasonal) variations.

The management of odorous emissions from sewer networks has become an important issue for sewer system operators resulting in the need to better understand the composition of reduced sulfur compounds (RSCs). Gaseous RSCs including hydrogen sulfide (H2S), methanethiol (MeSH), dimethyl sulfide (DMS), carbon disulfide (CS2), dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) were measured in the atmosphere of selected sewer networks in two major Australian cities (Sydney and Melbourne) during 2011-2012. The RSC concentrations in the sewer air were detected in a highly variable range.

Investigation of PM10 sources in Santa Catarina, Brazil through graphical interpretation analysis combined with receptor modelling.

Epidemiological studies have documented that elevated airborne particulate matter (PM) concentrations, especially those with an aerodynamic diameter less than 10 microm (PM10), are associated with adverse health effects. Two receptor models, UNMIX and positive matrix factorization (PMF), were used to identify and quantify the sources of PM10 concentrations in Tubarão and Capivari de Baixo, Santa Catarina, Brazil. This region is known for its high pollution levels due to intense industrial activity and exploitation of natural resources.

Is H2S a suitable process indicator for odour abatement performance of sewer odours?

Odour abatement units are typically designed and maintained on H(2)S concentrations, but operational failures are reported in terms of overall odour removal, suggesting a wide range of malodorous compounds emitted from sewers that may not be efficiently removed by existing odour abatement processes. Towards providing greater insight into this issue, several activated carbon filters and biofilters treating odorous emissions from sewer systems in Sydney (Australia) were monitored by collecting and analysing gas samples before and after treatment. The monitoring studies were conducted by both olfactometric measurements and gas-chromatography-based chemical analysis.

Stability of volatile sulfur compounds (VSCs) in sampling bags - impact of temperature.

Volatile sulfur compounds (VSCs) are a major component of odorous emissions that can cause annoyance to local populations surrounding wastewater, waste management and agricultural practices. Odour collection and storage using sample bags can result in VSC losses due to sorption and leakage. Stability within 72 hour storage of VSC samples in three sampling bag materials (Tedlar, Mylar, Nalophan) was studied at three temperatures: 5, 20, and 30 °C.

Odour emission ability (OEA) and its application in assessing odour removal efficiency.

Odourous emissions from sewer networks and wastewater treatment plants (WWTPs) can significantly impact a local population. Sampling techniques such as wind tunnels and flux hood chambers are traditionally used to collect area source samples for subsequent quantification of odour emission rates using dilution olfactometry, however these methods are unsuitable for assessing liquid samples from point sources due to the large liquid volumes required. To overcome this limitation, a gas phase sample preparation method was developed for assessing the total Odour Emission Ability (OEA) from a liquid sample.

Sewer odour abatement monitoring - an Australian survey.

Odourous emissions from sewer networks can significantly impact a local population causing odour annoyance. A survey of nine Australian wastewater utilities that serve over 8.4 million people and operate over 59,000 km of sewer networks was undertaken to summarise the current monitoring practices in Australia with the view to assist the water industry to further improve their practices in operating and monitoring sewer odour abatement systems.

Monitoring techniques for odour abatement assessment.

Odorous emissions from sewers and wastewater treatment plants are a complex mixture of volatile chemicals that can cause annoyance to local populations, resulting in complaints to wastewater operators. Due to the variability in hedonic tone and chemical character of odorous emissions, no analytical technique can be applied universally for the assessment of odour abatement performance. Recent developments in analytical methodologies, specifically gas chromatography, odour assessment approaches (odour wheels, the odour profile method and dynamic olfactometry), and more recently combined gas chromatography-sensory analysis, have contributed to improvements in our ability to assesses odorous emissions in terms of odorant concentration and composition.

Nitrous oxide monitoring for nitrifying activated sludge aeration control: a simulation study.

An activated sludge aeration control concept was developed utilizing off-gas nitrous oxide concentrations as a surrogate for autotrophic nitrifying bacterial inhibition and aeration air as a master control variable. The control concept was evaluated using a simulated pilot scale bioreactor (mathematically calibrated liquid phase process model and a model to link off-gas nitrous oxide generation to liquid phase conditions) as a data generator. When applied to the simulated system, the process controller was successful at maintaining the process at the desired operating setpoint and promoting stable operation by minimizing periods of significant inhibition.