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Biomedical subjects

H W Pearson

Publications and source records attributed to H W Pearson.

5 recordsLinked to original sources
PubMed2005

Implications for physical design: The effect of depth on the performance of waste stabilization ponds.

Studies on experimental primary facultative ponds showed that varying the depth from 1.25 m to 2.3 m had no effect on the rates of BOD removal. In contrast k values for FC removal rates were higher in the shallower (1.25 m) facultative ponds. The risk of odour release via H2S production was higher in the 2.2 m ponds than the 1.25 m ponds and NH3 removal was much better in the 1.25 m facultative ponds. A comparison of the efficiency of shallow 5-pond series (1.0 m and 0.61 m deep) with a 2.2 m deep series showed that the shallow systems were more efficient at FC removal, but the deeper series actually saved land area for the same FC final effluent quality under tropical conditions. However, efficient nutrient removal (N and P) only occurred in the shallow series and effluent standards for nutrient concentrations are unlikely to be met by 2.2 m deep 5-pond series in contrast to the norms for pathogen removal.

Ammonia↗
PubMed2005

Variations in BOD, algal biomass and organic matter biodegradation constants in a wind-mixed tropical facultative waste stabilization pond.

This study considered the impact of wind mixing on the efficiency of BOD removal and the first order biodegradation constant for organic matter in a primary facultative pond. Wind speeds of 1-4 m/s blowing from the effluent end of the pond towards the influent created surface-water flows of up to 0.94 m/s as determined by orange and coconut drogues moving in the opposite direction to the bulk hydraulic flow of 0.217 m/s. This was sufficient to cause mixing of the water column resulting in loss of stratification in terms of chlorophyll a, temperature and dissolved oxygen. BOD and chlorophyll a concentrations were spatially and temporally homogeneous throughout this large pond. BOD removal efficiency was only 50.30% as opposed to a projected value of 79% despite an acceptable surface organic loading of 350 kgBOD5/ha/d and an actual k value for BOD removal using influent sewage samples of 0.29 d-1 close to the projected value of 0.30 d-1. It would seem that wind mixing reduced pond efficiency by destroying stratification and thus reducing the microbial activity necessary to consume organic material. Mixing also increased the mean chlorophyll a concentration compared to stratified facultative ponds receiving similar loads and non-motile algae dominated the water column.

Biodegradation, Environmental↗
PubMed2001

Marine-based waste stabilisation ponds: an evaluation of the hydraulic viability.

Marine-Based Waste Stabilisation Ponds, formed by floating boom/skirt curtain enclosures anchored in sheltered waters, have recently been proposed for provision of low-cost effluent treatment facilities where land availability is limited in rapidly expanding coastal cities in the Third World. This paper outlines findings from a viability assessment, which drew on a preliminary site evaluation and baseline environmental survey (for a site in sheltered waters in the Far East), laboratory studies involving scale model tests in wave/wind/current flumes, and a structural and design loading study. It focuses on hydraulic and hydrodynamic considerations and reports the study's conclusions.

Industrial Waste↗