Nigel Horan

Measuring the effect of a hygiene behaviour intervention by indicators of behaviour and diarrhoeal disease

A social marketing approach used both qualitative and quantitative methods to develop a hygiene behaviour intervention in rural north-east Thailand. Behaviours were preselected from a previous study and the intervention was designed to promote hand washing, especially before feeding a baby, cooking, eating, and after defaecation or cleaning a babys bottom, and dish washing immediately after eating. A bacteriological indicator (enumerating faecal streptococci using a finger impression technique) was developed to measure changes in hand washing behaviour and observation (spot checks) of dirty dishes to indicate dish washing practice. There was a significant improvement in both behaviours and a significant reduction in diarrhoeal disease as a result of the intervention. Furthermore, both indicators were retrospectively found to be positively related to diarrhoeal disease incidence. However, receiving and being able to recall the intervention messages was not necessarily sufficient to ensure behaviour change, as some adults found it difficult to change old habits. Villages showing the greatest improvement tended to have a stronger sense of community than others and to have more people actively involved in the intervention.

Bioadsorption of pentachlorophenol (PCP) from aqueous solution by activated sludge biomass

The adsorption behavior of pentachlorophenol (PCP) from aqueous solution to activated sludge biomass was quantitatively characterized in this paper. The effects of the initial pH value and biomass concentration on bioadsorption were investigated. The Freundlich adsorption isotherm was applied to describe the biosorption processes and the isotherm constants were evaluated. The experimental results indicated that the initial pH value and biomass concentration are important parameters affecting the adsorption capacity that increased with decreasing biomass concentration (in the range less than 5 g/l) and pH (between 6 and 8). Both the biomass concentration and pH value only affected the capacity constant KF of the Freundlich equation while the intensity constant n remained constant.

Simple and rapid methods to evaluate methane potential and biomass yield for a range of mixed solid wastes

This paper describes rapid techniques to evaluate the methane potential and biomass yield of solid wastes. A number of solid wastes were mixed to provide a range of C:N ratios. Empirical formulae were calculated for each waste based on the results of chemical analysis and these formulae were used to estimate the COD equivalent and stoichiometric methane potential (SMP). The actual COD and biochemical methane potential (BMP) were determined experimentally for each waste and for both parameters there was a good agreement between the empirical and experimental values. The potential of adenosine triphosphate (ATP) to act as an indicator of biomass yield (mg VSS mg(-1) COD removed) was determined during the anaerobic digestion process. The biomass yield determined from ATP analysis was in the range 0.01-0.25mg VSS mg(-1) COD removed which corroborated well with previously reported studies. Empirical formula based SMP together with ATP measurement were shown to provide rapid methods to replace or augment the traditional BMP and VSS measurements and are useful for evaluating the bioenergy and biomass potential of solid wastes for anaerobic digestion.

Optimising the biogas production from leather fleshing waste by co-digestion with MSW

Waste from the leather industry, known as limed leather fleshing (LF), has a low C:N (3.2) and an alkaline pH of 11.4. This is a major disadvantage for anaerobic digestion due to ammonia toxicity for methanogenesis. This study describes co-digestion of LF with biodegradable fraction of municipal solids waste optimised over a range of C:N and pH to minimise ammonia and to maximise biogas yield. The optimum conditions were found with a blend that provided C:N of 15 and pH of 6.5 and the cumulative biogas yield increased from 560 mL using LF fraction alone, to 6518 mL with optimum blend. At higher pH of 8.5, unionised ammonia was high (2473 mg L(-1)) coincided with poor biogas yield (47 m Ld(-1)) that confirms ammonia toxicity. By contrast at a pH of 4.5 the ammonia was minimum (510 mg L(-1)), but high VFA (26,803 mg L(-1)) inhibited the methanogens. Biomass activity measured using ATP correlated well with biogas yield as reported previously.

The bacteriological quality of rainjar water in rural Northeast Thailand

Rainjars are popular in northeast Thailand because of the time and effort saved in water collection resulting from their use. Bacteriological analysis showed rainjar water to be much purer than drinking water from alternative sources (P < 0.001). In rainwater samples from one village, Escherichia coli was absent in 60% of rainjars compared with 46% of other vessels used for storing drinking water in the home (P < 0.01). The use of a tap and the physical height of the jar served to protect the water by limiting water handling. Moreover, mosquito netting fitted to the top of the rainjar significantly improved its water quality (P < 0.05), probably by preventing the access of small lizards. It is suggested that any systematic attempt to improve the quality of rainjar water further, in order to achieve the WHO guidelines, would be both problematic and expensive whilst the expected health benefits remain negligible. The problems of using drinking water quality guidelines for discrete supplies and the role of water analysis are discussed.

7 – Faecal indicator organisms

The fecal indicator organisms represent the first and foremost technique for detecting and quantifying the aquatic pollution. The role of fecal indicator organisms is central to the reduction of microbial pollution of water that occurrs in all parts of the world. Some of the properties of the ideal fecal indicator bacterium requires that they should be suitable for all the categories of water, present in wastewaters and polluted waters whenever the pathogens are present, present in greater numbers than pathogens, having similar survival characteristics as pathogens in waters, unable to multiply in waters, and non-pathogenic. The fecal coliforms, and particularly the E. coli, are the best overall indicators of the fecal pollution of waters. They are good indicators of bacterial pathogens, less good indicators of viral pathogens, but very poor indicators of the protozoan and helminthic pathogens. The fecal coliform numbers in the treated tropical wastewaters prove to be good indicators of the level of viral contamination.

The radial distribution and bioactivity of Pseudomonas sp immobilized in calcium alginate gel beads

Abstract Microorganisms capable of degrading di-n-butyl phthalate (DBP) were immobilized in calcium alginate gel beads. The radial distribution and bioactivity of the microbial cells within the gel beads were investigated. The dissolution of calcium alginate gel beads in sodium citrate (20 g/l) showed that the decrease in bead diameter was linear. The distribution of biomass inside the gel beads was heterogeneous, with progressively increased cellular density from the inside to the outside of the matrix. Measurements of oxygen-uptake rate of the immobilized cells, after release from the matrix by sodium citrate demonstrated the occurrence of a gradient of respiratory activity throughout the immobilized culture.

Optimisation of C:N Ratio for Co-Digested Processed Industrial Food Waste and Sewage Sludge Using the BMP Test

Biomethane production from processed industrial food waste (IFW) in admixture with sewage sludge (primary and waste activated sludge: PS and WAS) was evaluated at a range of C:N ratios using a standard biochemical methane potential (BMP) test. IFW alone had a C:N of 30 whereas for WAS it was 5.4 and thus the C:N ratio of the blends fell in that range. Increasing the IFW content in mix improves the methane potential by increasing both the cumulative biogas production and the rate of methane production. Optimum methane yield 239 mL/g VSremoved occurred at a C:N ratio of 15 which was achieved with a blend containing 11 percent (w/w) IFW. As the fraction of IFW in the blend increased, volatile solids (VS) destruction was increased and this led to a reduction in methane yield and amount of production. The highest destruction of volatile solids of 93 percent was achieved at C:N of 20 followed by C:N 30 and 15. A shortened BMP test is adequate for evaluating optimum admixtures.

Mathematical modelling of hydrogen sulphide emission and removal in aerobic biofilters comprising chemical oxidation

Four different empirical expressions have been compared for estimating the removal of hydrogen sulphide (H(2)S) from wastewater by chemical oxidation during its treatment in an aerated biofilter. The relative importance of this removal process is considered in a mass balance proposed by an emission model. Two of the four models investigated were able to predict the mean H(2)S removed fraction within a confidence interval of 95% and they demonstrated good agreement with experimental data. Biodegradation and oxidation were the two main removal mechanisms in the biofilter whereas stripping and volatilization made only minor contributions. However they can be of significance when the emission rates are calculated.

Institutional status and structure of wastewater quality management in Greece

In recent years sanitation programmes in Greece have been launched principally for domestic environmental reasons, but also because of the countrys commitment to comply with the common European Union (EU) environmental policy. The administration of these new programmes has been based on existing public services, and because of this a number of problems have arisen. This paper describes the institutional and administrative structure of wastewater treatment in Greece. An analysis and evaluation of the existing situation reveals that there is a significant number of problematic municipal wastewater treatment plants (MWTP). The agencies involved are described and evaluated and the importance of having specialised agencies is demonstrated. The effects of centralisation of the local administration under a pioneering national plan are predicted and recommendations for improving the institutional and administrative structure are made; taking into account the experience of other countries, local and national constraints, and the existing situation.