R. Perry

A review of atmospheric polycyclic aromatic hydrocarbons: Sources, fate and behavior

A review has been written to assess the sources, fate and behavior of polycyclic aromatic hydrocarbons (PAH) in the atmosphere. PAH are formed mainly by anthropogenic processes, especially the combustion of organic fuels. PAH concentration in air will reflect the location of source emitters, with high concentrations corresponding with urban and industrial areas. PAH are however ubiquitous contaminants of the environment having been detected in remote areas of the world. This is thought to be due to long term transport in the atmosphere. PAH can also be subjected to chemical and/ or photochemical change whilst resident in the atmosphere prior to their removal by either wet or dry deposition.

Low-cost adsorbents for waste and wastewater treatment: a review

The recent research interest in low-cost alternatives to activated carbon for waste and wastewater treatment is reviewed. An examination of the selection criteria and activation methods for the preparation of active carbon is followed by a critical assessment of low-cost adsorbents prepared from carbonaceous industrial wastes, agricultural by-products and mineral-derived sources. Emphasis is given to in situ reuse applications where stated in the literature and rudimentary economic analyses provided, where available, for comparative operations with commercial activated carbon.

The removal of phosphorus during wastewater treatment: A review

Phosphorus removal from wastewater can be achieved either through chemical removal, advanced biological treatment or a combination of both. The chemical removal of phosphorus involves the addition of calcium, iron and aluminium salts to achieve phosphorus precipitation by various mechanisms which are discussed. In addition, the effects of operating conditions, especially wastewater characteristics; sludge production in terms of quality and quantity; optimisation of chemical use and re-use; points of chemical addition combined with biological treatment; alternative chemical/physical treatments and examples of full-scale applications are also reviewed. Biological phosphorus removal is dependent upon the uptake of phosphorus in excess of normal bacterial metabolic requirements and is proposed as an alternative to chemical treatment. Early developments and the postulated removal mechanisms are reviewed; these include either natural chemical precipitation, enhanced biological removal, or a combination of both. The nature of excess biological phosphorus removal in activated sludge wastewater treatment plants is evaluated, considering various operating parameters, bacteriology and process designs.

Indoor air quality in homes, offices and restaurants in Korean urban areas—indoor/outdoor relationships

Air quality monitoring was carried out to collect data on the levels of various indoor and ambient air constituents in two cities in Korea (Seoul and Taegu). Sampling was conducted simultaneously indoors and outdoors at six residences, six offices and six restaurants in each city during summer 1994 and winter 1994–1995. Measured pollutants were respirable suspended particulate matter (RSP), carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), and a range of volatile organic compounds (VOCs). In addition, in order to evaluate the effect of smoking on indoor air quality, analyses of parameters associated with environmental tobacco smoke (ETS) were undertaken, which are nicotine, ultraviolet (UVPM), fluorescence (FPM) and solanesol particulate matter (SolPM). The results of this study have confirmed the importance of ambient air in determining the quality of air indoors in two major Korean cities. The majority of VOCs measured in both indoor and outdoor environments were derived from outdoor sources, probably motor vehicles. Benzene and other VOC concentrations were much higher during the winter months than the summer months and were not significantly greater in the smoking sites examined. Heating and cooking practices, coupled with generally inadequate ventilation, also were shown to influence indoor air quality. In smoking sites, ETS appears to be a minor contributor to VOC levels as no statistically significant relationships were identified with ETS components and VOCs, whereas very strong correlations were found between indoor and outdoor levels of vehicle-related pollutants. The average contribution of ETS to total RSP concentrations was estimated to range from 10 to 20%.

Analysis and interpretation of air quality data from an urban roadside location in Central London over the period from July 1991 to July 1992

Abstract Air quality data from a one year study at an urban roadside location in Central London are reported for a large number of both organic and inorganic air pollutants. The location is 5 m from the kerbside of a moderately busy road, Exhibition Road, enclosed on each side by buildings. The pollutants measured included NO, NO2, O3, SO2, CO and CO2. together with 28 non-methane hydrocarbons, including measurements of the air toxics: benzene and 1,3-butadiene. The interpretation of the air quality data used simple statistical techniques, including principal components analysis, and air pollution models of the Gaussian plume and box model variety. A comprehensive validation of the published emission inventory estimates for London was attempted using the observed air quality data. Separate contributions from the local traffic on Exhibition Road, from the general traffic in Central London, natural gas leakage and fuel combustion have been identified. The agreement between the emission factors required to explain the observed concentrations and those in the literature was excellent for a number of air pollutants and these should be of value in environmental impact assessments. Attention was also directed to an intense wintertime pollution episode which occurred during the study period, when the concentrations of all pollutants were considerably higher than usual. Elevated nitrogen dioxide concentrations were a significant feature of this episode and the box model was used to ascertain its likely production mechanism. A relationship between the hourly mean nitrogen dioxide and NOx concentrations was defined which should have general applicability in air quality policy assessments.

Handbook of air pollution analysis

This book is intended to provide a comprehensive working knowledge of the theory and practice of air pollution analysis. An attempt has been made both to review recently reported developments in air pollution analysis and to present detailed descriptions of established analytical procedures which have been used in the evaluation of air pollution problems of various types. Chapters are included under the following headings: (1) general sampling techniques, (2) analysis of particulate pollutants, (3) metal analysis, (4) nitrogen and sulphur compounds, (5) secondary pollutants, (6) hydrocarbons and carbon monoxide, (7) halogen containing compounds, (8) remote monitoring techniques, and (9) planning and execution of an air pollution study. /TRRL/

Phase distribution and particle size dependency of polycyclic aromatic hydrocarbons in the urban atmosphere

Abstract Distributional characteristics of polycyclic aromatic hydrocarbons in urban air were investigated with respect to gas-particle partitioning and dependency on particle size. The relationship between the gas particle distributions of PAH and ambient temperature was described using the Langmuir adsorption concept, while the particle size dependency was demonstrated based on a Lundgren type mass distribution.

Vehicle emissions in relation to fuel composition

In recent years there has been growing concern over the impact of non-regulated pollutants produced by vehicles and in particular the role of specific volatile organic compounds (VOCs). As yet there is limited information on the effect of changing fuel compositions on VOC emissions from gasoline fuelled vehicles. The basis of this study was, therefore, to investigate the relationship between emissions and fuel quality and consider its implications with respect to both indoor and outdoor air quality. Dynamometer studies were conducted using a standard test cycle and the total exhaust emissions over the complete cycle were sampled for subsequent analysis. Tests were performed on a variety of gasolines with differing amounts of olefin and aromatic compounds and the concentrations of specific VOCs were measured together with other pollutants of concern. Results of these studies were considered in relation to the changes in VOC emissions that could be released into street air as a result of using the fuels tested. In addition, in highly urbanised countries where dwellings and work places are in close proximity to vehicle traffic, changes in outdoor air quality will also be reflected in indoor air.

The balance of heavy metals through a sewage treatment works I. Lead, cadmium and copper

Abstract Concentrations of lead, cadmium and copper have been determined in the sewage sludges, sewages and effluent of a sewage treatment works. Treatment at this works is by primary sedimentation prior to biological treatment in a diffused air activated sludge plant. By analysis of composite samples corresponding to a 24-h input of raw sewage to the works, a mass balance of metals through the works has been estimated. The partition of the metals from raw sewage into the settled sewage and primary sludge, and from the settled sewage into the activated sludge and final effluent has been quantified.

Organic compounds in the cement-based stabilisation/ solidification of hazardous mixed wastes—Mechanistic and process considerations

Abstract The pretreatment of hazardous wastes by cement-based stabilisation/solidification is of increasing importance as an alternative to the direct landfill of toxic materials. Inorganic and organic compounds are known to have a range of beneficial or harmful effects on cement hydration and their presence within construction materials has been strictly controlled. This paper reviews cement and pozzolanic hydration and the use of organic admixtures as a prerequisite to a discussion of the effects of organic wastes in cement. The pre-adsorption of organic contaminants is reviewed and presented as a potential extension of existing solidification processes for the successful treatment of mixed organic/inorganic wastes.