Biomedical subjects

P Gostelow

Publications and source records attributed to P Gostelow.

5 recordsLinked to original sources

PubMed2005

Membrane gas absorbers for H2S removal--design, operation and technology integration into existing odour treatment strategies.

A hollow fibre (HF) polypropylene membrane gas absorber was investigated for the removal of hydrogen sulphide (H2S) from gas streams. Gas concentrations between 25-2010 ppmV were fed into the shell side of a membrane module whilst water-NaOH solutions flowed counter-currently in the fibre lumens. The process was effective at removing the H2S (96% at G:L ratios up to 50 and pH 13) from the gas phase in a single pass through the membrane at all the concentrations of HaS investigated. Analysis of the mass transfer process revealed the rate of transfer to be controlled by the gas phase transfer coefficient with a value between 1 and 25 x 10(-4) m.s(-1). The possible integration of a membrane absorber system into existing odour treatment strategies was assessed by comparing the membrane system, based on the experimentally determined mass transfer coefficient, with existing full scale biofiltration plants. The membrane system became economically favourable at gas flow rates lower than 1630 m(3) x h(-1).

Adsorption↗

PubMed2004

Odour management plans: a risk-based approach using stakeholder data.

Annoyance is a familiar reaction to odours arising from wastewater treatment sites, a reaction which can result in complaints and prosecutions. Odour management plans can be used to assess the extent of nuisance caused and prioritise mitigation measures. Often, these plans have been developed purely on the basis of technical assessments of emission and dispersion, with the general aim of limiting odour concentrations to a specific threshold at some distance from the works. They have often been prepared with inconsistent communication between the site staff and consultant during the development process, and may not directly refer to the affected population. This paper describes a risk-based approach to developing odour management plans, in which mitigation measures are assessed and prioritised on the basis of the likely frequency and intensity of odour exposure. A key element of the approach is the use of knowledge from data gained from key stakeholder groups: customers, staff, and regulators. Emphasis is placed on the development of clear communications between these groups, which helps both in terms of raising awareness amongst operators as to the significance of odour problems, and also in managing the expectations of customers and regulators. The practical application of this approach is demonstrated by the development of odour management plans for wastewater treatment sites by Yorkshire Water Services Ltd. These have used data from staff, customers and regulators to develop risk grids, which are then used to prioritise remediation measures. Involving staff in the data collection operations has been successful in raising awareness of the significance of odours, and has in turn led to low-cost emission reductions through improved housekeeping. Improved communications between operators, customers and regulators has led to more realistic expectations with regard to odour problems, a situation which can reduce conflict and prevent the imposition of stringent and sometimes unrealistic odour standards.

Communication↗

PubMed2004

Integrated odour modelling for sewage treatment works.

Odours from sewage treatment works are a significant source of environmental annoyance. There is a need for tools to assess the degree of annoyance caused, and to assess strategies for mitigation of the problem. This is the role of odour modelling. Four main stages are important in the development of an odour problem. Firstly, the odorous molecules must be formed in the liquid phase. They must then transfer from the liquid to the gaseous phase. They are then transported through the atmosphere to the population surrounding the odour source, and are then perceived and assessed by that population. Odour modelling as currently practised tends to concentrate on the transportation of odorants through the atmosphere, with the other areas receiving less attention. Instead, odour modelling should consider each stage in an integrated manner. This paper describes the development of integrated odour models for annoyance prediction. The models describe the liquid-phase transformations and emission of hydrogen sulphide from sewage treatment processes. Model output is in a form suitable for integration with dispersion models, the predictions of which can in turn be used to indicate the probability of annoyance. The models have been applied to both hypothetical and real sewage treatment works cases. Simulation results have highlighted the potential variability of emission rates from sewage treatment works, resulting from flow, quality and meteorological variations. Emission rate variations can have significant effects on annoyance predictions, which is an important finding, as they are usually considered to be fixed and only meteorological variations are considered in predicting the odour footprint. Areas for further development of integrated odour modelling are discussed, in particular the search for improved links between analytical and sensory measurements, and a better understanding of dose/response relationships for odour annoyance.

Air Pollutants↗

PubMed2001

Odour measurements for sewage treatment works.

Public concern over odours from sewage treatment works is increasing. More people are being exposed to odours, due to development around existing works or construction of new works. Increased awareness of both the environment and individual rights has meant people are now more likely to complain. Odour abatement and control is a major issue for sewage works operators. To control odours, they must first be measured. This is no easy task as response to odours is subjective. Our understanding of the sense of smell is incomplete, and there is no single measure that will directly relate to the likelihood of complaint. Odour measurement has often been regarded as an art as opposed to a science. Odour measurement techniques fall into two classes. Sensory measurements employ the human nose and measure the effects of the odour as perceived by an observer. Analytical measurements characterise odours in terms of their chemical composition and attempt to quantify the odorants present. Both methods are less than ideal--sensory measurements can be overly subjective and the interpretation of results requires care. Analytical measurements are complicated by the large number of odorants present, often at concentrations close to detection limits. Our incomplete understanding of odour perception makes linking analytical and sensory measurements difficult. This paper reviews the methods applied to sewage treatment works odour measurement. Sensory and analytical measurements are reviewed, along with a recent development, the electronic nose.

Humans↗

PubMed2001

Development of an odorant emission model for sewage treatment works.

In the field of odour assessment, much attention has been paid to the measurement of odour concentration. Whilst the concentration of an odour at a receptor is a useful indicator of annoyance, the concentration at the source tells only half the story. The emission rate - the product of odour concentration and air flow rate - is required to appreciate the significance of odour sources. Knowledge of emission rates allows odour sources to be ranked in terms of significance and facilitates appropriate selection and design of odour control units. The emission rate is also a key input for atmospheric dispersion models. Given the increasing importance of odour to sewage treatment works operators, there is a clear need for predictive methods for odour emission rates. Theory suggests that the emission of odorants from sewage to air is controlled by mass transfer resistances in both the gas and liquid phase. These are in turn controlled by odorant and emission source characteristics. The required odorant characteristics are largely known, and mass transfer from many different types of emission sources have been studied. Sewage treatment processes can be described by one or more of six characteristic emission sources, these being quiescent surfaces, channels, weirs and drop structures, diffused aeration, surface aeration and flow over media. This paper describes the development of odorant mass transfer models for these characteristic emission types. The models have been applied in the form of spreadsheet models to the prediction of H2S emissions and the results compared with commercial VOC emission models.

Air Movements↗