CERES :: Browsing by Author "Parsons, Simon A."

Browsing by Author "Parsons, Simon A."

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Open Access
The aeration of clay soils in cricket
(Cranfield University, 2012-05) Parsons, Simon A.; James, Iain; Bartlett, Mark
In the game of cricket good ball-surface interactions are essential and require a hard, flat surface. To achieve this the clay loam soil comprising the pitch is compressed and compacted using a smooth wheeled roller, which when combined with the drying action of the grass plant roots, causing the clay minerals within the soil to shrink, creates a high bulk density, hard surface on which to play. High bulk density soils present difficult growing conditions for plants due to high mechanical resistance, reduced hydraulic conductivity and gas exchange capability. The hydraulic properties and gas exchange capability are linked to the connectivity and tortuosity of the pore network as well as pore size; all of which are diminished by compaction of the soil. Aeration is currently utilised as a tool to ameliorate the negative effects of compaction on the growing environment of the plant roots. Little research exists that describes the actions of aeration in clay loam soils. The current guidelines for aeration and the proof for its efficacy in cricket are based almost entirely on anecdotal evidence. A diverse methodology was used to meet the project objectives. This diversity reflects the broad nature of the expectations of the cricket groundsmen from aeration of pitches as reflected in a survey of current practise undertaken during the project. Novel experimental methods were used to examine the effect of aeration on soil atmospheres in the laboratory and under field conditions. The laboratory experiment revealed that vertically-operated solid tines did significantly increase the rate of diffusion through the soil, however in the field, this rate increase was only apparent after significant rainfall. New methods utilising time-lapse photography and automated image analysis quantified the magnitude of swelling in a range of soils in response to increasing water content over time to a high degree of accuracy. A similar method was employed to examine the shrinkage of the same soils as the water content was reduced, examining not only the magnitude but also the cracking patterns formed. These experiments aimed to examine the soils natural ability to recover from compaction over time. The soils natural ability to recover from compaction through shrink-swell and freeze-thaw was evident in the field trials. These field trials examined five diverse aeration treatments to examine the physical and biological effects they have on the soil. The field trials showed generally small and inconsistent effects on the physical properties of the soil from aeration treatments when compared to the natural processes of shrink-swell and freeze-thaw. One consistent effect from aeration was a 2% reduction in moisture content in one particular soil type. Aeration was found to have no effect on soil microbial biomass nor on soil organic matter content. In a pot experiment examining the effect of aeration in a range of soil densities the total root mass was not diminished by increasing soil density but became increasingly concentrated upwards in the profile. Aeration was found to slightly increase the root mass but only in the highest bulk density treatment (1.90 g cm-3) at depths below 75 mm. A set of guidelines were developed based on the evidence garnered from the experiments with a clearly defined decision process for choosing the most suitable equipment for the treatment aim. It is hoped that these guidelines will provide an informative reference for current and future groundsmen to ensure the optimum use of often scarce and valuable resources when choosing an aeration treatment.
Open Access
Carbonaceous and nitrogenous disinfection by-product formation from algal organic matter
(Elsevier, 2016-12-10) Goslan, Emma Harriet; Seigle, Céline; Purcell, Diane; Henderson, Rita Kay; Parsons, Simon A.; Jefferson, Bruce; Judd, Simon J.
Seasonal algal blooms in drinking water sources release intracellular and extracellular algal organic matter (AOM) in significant concentrations into the water. This organic matter provides precursors for disinfection by-products (DBPs) formed when the water is subsequently chlorinated at the final disinfection stage of the potable water treatment process. This paper presents results of AOM characterisation from five algal species (three cyanobacteria, one diatom and one green) alongside the measurement of the DBP formation potential from the AOM of six algal species (an additional diatom). The character was explored in terms of hydrophilicity, charge and protein and carbohydrate content. 18 DBPs were measured following chlorination of the AOM samples: the four trihalomethanes (THMs), nine haloacetic acids (HAAs), four haloacetonitriles (HANs) and one halonitromethane (HNM). The AOM was found to be mainly hydrophilic (52 and 81%) in nature. Yields of up to 92.4 μg mg−1 C carbonaceous DBPs were measured, with few consistent trends between DBP formation propensity and either the specific ultraviolet absorbance (SUVA) or the chemical characteristics. The AOM from diatomaceous algae formed significant amounts of nitrogenous DBPs (up to 1.7 μg mg−1 C). The weak trends in DBPFP may be attributable to the hydrophilic nature of AOM, which also makes it more challenging to remove by conventional water treatment processes.
Open Access
Chemical and biological oxidation of NOM surrogates and effect on HAA formation
(Elsevier, 2009-06) Bond, Tom; Goslan, Emma Harriet; Jefferson, Bruce; Roddick, F.; Fan, L.; Parsons, Simon A.
Formation of disinfection by-products (DBPs) can be controlled by removal of disinfection by-product precursors before disinfection. Variable success has been reported, depending on the treatment used and water tested. Chemical and biological oxidations are candidate technologies to control DBP formation. Given the uncertainty over the identity of DBP precursors, the use of surrogates of natural organic matter (NOM) allows fundamental probing of the links between compound character, removal and DBP formation. Nine compounds were chosen to represent NOM and their removal by two advanced oxidation processes (AOPs), UV-C irradiation and biological treatment compared while haloacetic acid (HAA) formation before and after treatment was measured. Although AOPs were able to fully remove all compounds, incomplete mineralisation led to increased HAA levels, dramatically in the case of two amino acids. Biological treatment was effective in removing amino acids but also moderately increased the HAA formation potential (HAAFP) of hydrophilic compounds. These findings indicate waters with high amino acid concentrations will be susceptible to raised HAA levels following AOP treatment and careful process selection for HAA control is required in such cases.
Open Access
Comparison between disintegrated and fermented sewage sludge for production of a carbon source suitable for biological nutrient removal
(Elsevier Science B.V., Amsterdam., 2010-03-15T00:00:00Z) Soares, Ana; Kampas, Pantelis; Maillard, Sarah; Wood, Elizabeth; Brigg, Jon; Tillotson, Martin; Parsons, Simon A.; Cartmell, Elise
There is a need to investigate processes that enable sludge re-use while enhancing sewage treatment efficiency. Mechanically disintegrated thickened surplus activated sludge (SAS) and fermented primary sludge were compared for their capacity to produce a carbon source suitable for BNR by completing nutrient removal predictive tests. Mechanically disintegration of SAS using a deflaker enhanced volatile fatty acids (VFAs) content from 92 to 374 mg l−1 (4.1-fold increase). In comparison, primary sludge fermentation increased the VFAs content from 3.5 g l−1 to a final concentration of 8.7 g l−1 (2.5-fold increase). The carbon source obtained from disintegration and fermentation treatments improved phosphate (PO4-P) release and denitrification by up to 0.04 mg NO3-N g−1 VSS min−1 and 0.031 mg PO4-P g−1 VSS min−1, respectively, in comparison to acetate (0.023 mg NO3-N g−1 VSS min−1and 0.010 mg PO4-P g−1 VSS min−1). Overall, both types of sludge were suitable for BNR but disintegrated SAS displayed lower carbon to nutrient ratios of 8 for SCOD:PO4-P and 9 for SCOD:NO3-N. On the other hand, SAS increased the concentration of PO4-P in the settled sewage by a further 0.97 g PO4-P kg−1 SCOD indicating its potential negative impact towards nutrient recyc
Open Access
Comparison of coagulation performance and floc properties using a novel zirconium coagulant against traditional ferric and alum coagulants
(Elsevier Science B.V., Amsterdam., 2012-09-03T00:00:00Z) Jarvis, Peter; Sharp, Emma; Pidou, Marc; Molinder, Roger; Parsons, Simon A.; Jefferson, Bruce
Coagulation in drinking water treatment has relied upon iron (Fe) and aluminium (Al) salts throughout the last century to provide the bulk removal of contaminants from source waters containing natural organic matter (NOM). However, there is now a need for improved treatment of these waters as their quality deteriorates and water quality standards become more difficult to achieve. Alternative coagulant chemicals offer a simple and inexpensive way of doing this. In this work a novel zirconium (Zr) coagulant was compared against traditional Fe and Al coagulants. The Zr coagulant was able to provide between 46 and 150% lower dissolved organic carbon (DOC) residual in comparison to the best traditional coagulant (Fe). In addition floc properties were significantly improved with larger and stronger flocs forming when the Zr coagulant was used with the median floc sizes being 930 υm for Zr; 710 υm for Fe and 450 υm for Al. In pilot scale experiments, a similar improved NOM and particle removal was observed. The results show that when optimised for combined DOC removal and low residual turbidity, the Zr coagulant out-performed the other coagulants tested at both bench and pilot sca
Open Access
Comparison of the disinfection by-product formation potential of treated waters exposed to chlorine and monochloramine
(Elsevier, 2010-02) Bougeard, M. M.; Goslan, Emma Harriet; Jefferson, Bruce; Parsons, Simon A.
The formation of disinfection by-products (DBPs) from chlorination and monochloramination of treated drinking waters was determined. Samples were collected after treatment at 11 water treatment works but before exposure to chlorine or monochloramine. Formation potential tests were carried out to determine the DBPs formed by chlorination and monochloramination. DBPs measured were trihalomethanes (THMs), haloacetic acids (HAAs), halonitromethanes (HNMs), haloacetonitriles (HANs), haloaldehydes (HAs), haloketones (HKs) and iodo-THMs (i-THMs). All waters had the potential to form significant levels of all the DBPs measured. Compared to chlorine, monochloramination generally resulted in lower concentrations of DBPs with the exception of 1,1-dichloropropanone. The concentrations of THMs correlated well with the HAAs formed. The impact of bromine on the speciation of the DBPs was determined. The literature findings that higher bromide levels lead to higher concentrations of brominated DBPS were confirmed.
Open Access
Computational Fluid Dynamics Modelling of Flocculation in Water Treatment: A Review
(2009-06-30T00:00:00Z) Bridgeman, J.; Jefferson, Bruce; Parsons, Simon A.
The principal focus of this paper is to present a critical review of current approaches to modelling the inter-related hydrodynamic, physical and chemical processes involved in the flocculation of water using Computational Fluid Dynamics (CFD). The flows inside both laboratory and full scale mechanically- mixed flocculators are complex and pose significant challenges to modellers. There exists a body of published work which considers the bulk flow patterns, primarily at laboratory scale. However, there is little reported multiphase modelling at either scale. Two-equation turbulence modelling has been found to produce variable results in comparison with experimental data, due to the anisotropic nature of the swirling flow. However, the computational expense of combining the sliding mesh treatment for a rotating mesh with the Reynolds Stress Model (RSM) in a full scale unit is great, even when using a high performance computing facility. Future work should focus more on the multiphase modelling aspects. Whilst opportunities exist for particle tracking using a Lagrangian model, few workers have attempted this. The fractal nature of flocs poses limitations on the accuracy of the results generated and, in particular, the impacts of density and porosity on drag force and settlement characteristics require additional work. There is significant scope for the use of coupled population balance models and CFD to develop water treatment flocculation models. Results from related work in the wastewater flocculation field are encouraging.
Open Access
Fouling control of a membrane coupled photocatalytic process treating greywater
(Elsevier Science B.V., Amsterdam., 2009-09-01T00:00:00Z) Pidou, Marc; Parsons, Simon A.; Raymond, Gaelle; Jeffrey, Paul; Stephenson, Tom; Jefferson, Bruce
Fouling in membrane coupled photocatalytic reactors was investigated in the case of greywater treatment by establishing the link between product type, dose, irradiation time and fouling rates in a cross flow membrane cell fitted with a 0.4 μm pore sized polyethylene membrane. Rapid fouling occurred only with shower gels and conditioners and was linked to changes in the organo-TiO2 aggregate size postulated to be caused by polymers within the products. Fouling was reduced to a negligible level when sufficient irradiation was applied demonstrating that the membrane component of the process is not the issue and that scale up and implementation of the process relates to effective design of the UV reactor
Open Access
The impact of barley straw conditioning on the inhibition of Scenedesmus using chemostats
(Elsevier Science B.V., Amsterdam., 2010-03-31T00:00:00Z) Murray, Daniel; Parsons, Simon A.; Jarvis, Peter; Jefferson, Bruce
The current paper investigates the role of barley straw conditioning on inhibiting the alga Scenedesmus. Fresh, pre-rotted and white rot fungi (WRF) augmented straw was tested in a series of chemostat experiments over 15 weeks. All three systems were effective at inhibiting the alga with differences observed in the lag time before inhibition occurred and the rate of alga decline. Lag times of 8, 4 and 1 week(s) were recorded for the fresh, rotted and fungi-treated straws, respectively, with a maximum inhibition rate of >7 x 10(4) cells week (1) observed for the fungi pre-treated system. Overall, the results indicate that pre-treatment is a viable method to enable barley straw to be used in a more reactive manner. Explanation is postulated that during pre-treatment no alternative sources of nitrogen are available, thereby leading to greater bacterial decomposition of straw lignin to release inhibitory substances. The principle of utilising an engineered pre-treatment by inoculating barley straw with WRF to enhance the impact of the straw on algal inhibition has been clearly demonstrated. Further work is required to understand how the straw pre-treatment stage can be reduced to minimise its duration while maximising the inhibitory effect of adding barley straw. (C) 2009 Elsevier Ltd. All rights reserved.
Open Access
Impact of calcium on struvite crystal size, shape and purity.
(Elsevier, 2005-10-01) Le Corre, Kristell S.; Valsami-Jones, Eugenia; Hobbs, Phil; Parsons, Simon A.
Struvite precipitation occurs spontaneously in wastewater treatment plants under conditions that are influenced by many factors including concentration of , and ions, pH, temperature and mixing energy. These parameters are often difficult to control and as a result struvite generates problems of scale deposits in areas such as pipes and recirculation pumps. At the same time, struvite is considered as a potentially marketable product as an alternative fertiliser. For those two reasons, it has become important to study the principles of struvite precipitation, and to assess the parameters controlling struvite crystallisation. In the present work the influence of ions on the precipitation of struvite was investigated in aqueous solution containing , and ions in a molar ratio 1:2:2 at room temperature and constant pH. Different laboratory experiments have been used to assess the effects of Ca2+ ions on size, shape, and purity of the crystals formed. Tools used include particle size analysis, X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS). The experimental results showed that the presence of calcium in the media can affect significantly struvite crystal growth, and the characteristics of the crystal produced.
Open Access
The impact of differing cell and algogenic organic matter (AOM) characteristics on the coagulation and flotation of algae
(Elsevier, 2010-06) Henderson, Rita Kay; Parsons, Simon A.; Jefferson, Bruce
The aim of this study was to compare the coagulation and flotation of different algae species with varying morphology and algogenic organic matter (AOM) composition in order to link physical and chemical algae characteristics to treatment. Microcystis aeruginosa (cyanobacteria), Chlorella vulgaris (green algae), Asterionella formosa and Melosira sp. (diatoms) were treated by coagulation with aluminium sulphate and flotation. The AOM was extracted and treated separately. Analyses included cell counts, dissolved organic carbon, aluminium residual and zeta potential. Removal efficiencies in the range 94–99% were obtained for each species. Cells, AOM and aluminium were concurrently removed at a coagulant dose that was related on a log–log basis to both cell surface area and total charge density, although the relationship was much stronger for the latter. This was attributed to a significant proportion of the coagulant demand being generated by the AOM. The implications of such findings are that relatively simple charge measurements can be used to understand and control coagulation and flotation of algae.
Open Access
Impact of Reactor Operation on Success of Struvite Precipitation from Synthetic Liquors
(Taylor & Francis, 2007-11-30T00:00:00Z) Le Corre, Kristell S.; Valsami-Jones, Eugenia; Hobbs, Phil; Parsons, Simon A.
A pilot scale reactor was designed and developed to study struvite crystallisation principles. The present work focuses on the possible impact of the reactor's operating parameters on struvite characteristics, and evaluates the performances of the process in removing phosphorus. Struvite precipitation from synthetic liquors was investigated under various situations including: pH, magnesium dosing, addition of foreign ions such as calcium and increasing retention time. Small variations of a these parameters were found to have significant effects on struivite crystal characteristics and/or production. For instance, an increase of pH from 10.0 to 10.5 favoured the formation of Mg3(PO4)2.22H2O rather than struvite. For molar ratios Ca:Mg above 1:1, calcium ions competed with magnesium to form an amorphous calcium phosphate, hence inhibiting struvite formation. With regards to crystal growth, the process showed some limitations. Indeed, large amounts ot fines were produced, and crystal rarely grew over 100 pm under optimum conditions, Based on those observations, zeta-potential measurements of struvite crystals were investigated. Results revealed highly negative zeta-potential values for all experiments, indicating that this may be a limitation to struvite tendency for agglomeration.
Open Access
Incorporating biodegradation and advanced oxidation processes in the treatment of spent metalworking fluids
(Taylor & Francis, 2012-04-27T00:00:00Z) MacAdam, Jitka; Ozgencil, Haci; Autin, Olivier; Pidou, Marc; Temple, Clive; Parsons, Simon A.; Jefferson, Bruce
The treatment of spent metalworking fluids (MWFs) is difficult due to their complex and variable composition. Small businesses often struggle to meet increasingly stringent legislation and rising costs as they need to treat this wastewater on site annually over a short period. Larger businesses that treat their wastewater continuously can benefit from the use of biological processes, although new MWFs designed to resist biological activity represent a challenge. A three-stage treatment is generally applied, with the oil phase being removed first, followed by a reduction in COD loading and then polishing of the effluent's quality in the final stage. The performance of advanced oxidation processes (AOPs), which could be of benefit to both types of businesses was studied. After assessing the biodegradability of spent MFW, different AOPs were used (UV/H2O2, photo-Fenton and UV/TiO2) to establish the treatability of this wastewater by hydroxyl radicals (•OH). The interactions of both the chemical and biological treatments were also investigated. The wastewater was found to be readily biodegradable in the Zahn–Wellens test with 69% COD and 74% DOC removal. The UV/TiO2 reactor was found to be the cheapest option achieving a very good COD removal (82% at 20min retention time and 10Lmin−1 aeration rate). The photo-Fenton process was found to be efficient in terms of degradation rate, achieving 84% COD removal (1M Fe2+, 40M H2O2, 20.7Jcm−2, pH 3) and also improving the wastewater's biodegradability. The UV/H2O2 process was the most effective in removing recalcitrant COD in the post-biological treatment stage.
Open Access
Influence of granular activated carbon media properties on natural organic matter and disinfection by-product precursor removal from drinking water
(Elsevier / IWA, 2020-02-15) Golea, D. M.; Jarvis, Peter; Jefferson, Bruce; Moore, Graeme; Sutherland, S.; Parsons, Simon A.; Judd, Simon J.
Operational and financial constraints challenge effective removal of natural organic matter (NOM), and specifically disinfection by-product (DBP) precursors, at remote and/or small sites. Granular activated carbon (GAC) is a widely used treatment option for such locations, due to its relatively low maintenance and process operational simplicity. However, its efficacy is highly dependent on the media capacity for the organic matter, which in turn depends on the media characteristics. The influence of GAC media properties on NOM/DBP precursor removal has been studied using a range of established and emerging media using both batch adsorption tests and rapid small-scale column tests. DBP formation propensity (DBPFP) was measured with reference to trihalomethanes (THMs) and haloacetic acids (HAAs). All GAC media showed no selectivity for specific removal of precursors of regulated DBPs; DBP formation was a simple function of residual dissolved organic carbon (DOC) levels. UV254 was found to be a good surrogate measurement of DBPFP for an untreated water source having a high DOC. Due to the much-reduced concentration of DBP precursors, the correlation was significantly poorer for the coagulation/flocculation-pretreateed water source. Breakthrough curves generated from the microcolumn trials revealed DOC removal and consequent DBP reduction to correlate reasonably well with the prevalence pores in the 5–10 nm range. A 3–6 fold increase in capacity was recorded for a 0.005–0.045 cm3/g change in 5–10 nm-sized pore volume density. No corresponding correlation was evident with other media pore size ranges.
Open Access
Kinetic study of adsorption and photo-decolorization of Reactive Red 198 on TiO2 surface
(Elsevier, 2009-12-15) Dutta, S.; Parsons, Simon A.; Bhattacharjee, C.; Jarvis, Peter; Datta, S.; Bandyopadhyay, S.
Recycling and reuse of wastewater after purification will reduce the environmental pollution as well as fulfill the increasing demand of water. Adsorption-based water treatment process is very popular for dye-house wastewater treatment. The present study deals with treatment of wastewater contaminated by reactive dye. TiO2 is used as adsorbent and the spent adsorbent has been regenerated by Advanced Oxidation Process (AOP), without using any other chemicals. TiO2 adsorbs dye molecules and then those dye molecules have been oxidized via a photocatalytic reaction in presence of UV irradiation. Kinetics of dye adsorption and photocatalytic oxidation reaction has been developed in this study. Photocatalyst adsorbent (TiO2) has been reused several times after regeneration. The activity of catalyst decreases after each cycle; due to poisoning cause by intermediate by-products. Kinetic of this catalyst deactivation has been incorporated with L–H model to develop the photocatalytic reaction kinetic model.
Open Access
Kinetics of Struvite Precipitation: Effect of the Magnesium Dose on Induction Times and Precipitation Rates
(Taylor & Francis, 2007-12-31T00:00:00Z) Le Corre, Kristell S.; Valsami-Jones, Eugenia; Hobbs, Phil; Parsons, Simon A.
The presence of white deposits in specific areas of wastewater treatment plants is generally the consequence of the spontaneous formation of a mineral called struvite. Struvite forms when the levels of phosphate, ammonium and magnesium naturally available in wastewater effluents reach a minimum molar ratio 1:1:1 under specific conditions of pH, temperature and mixing energy. Originally regarded as a phenomenon to be controlled or eliminated, struvite has been lately identified as an alternative way of removing and recovering P from wastewater effluents and generating a product identified as an excellent base for the production of slow release fertilisers. Chemical and physical principles of struvite precipitation and the development of crystallisation technologies have been widely investigated. However, little interest has been given to kinetics of struvite precipitation. In the present work the kinetics of struvite formation have been investigated at both laboratory and pilot scale in synthetic solutions containing Mg2+, NH41, and PO43- ions in a molar ratio 1:2:2 at room temperature. These different tests have used pH measurements to assess the impact of water chemistry on induction times, and more precisely the influence of magnesium levels on kinetic rates. Experimental results and kinetic calculatio revealed that the control of the magnesium dose initially present in solution is decisive of the speed at which struvite nucleates.
Open Access
Magnetic ion-exchange resin treatment: Impact of water type and resin use
(Elsevier Science B.V., Amsterdam., 2008-04-30T00:00:00Z) Mergen, Maxime Rodolphe Denis; Jefferson, Bruce; Parsons, Simon A.; Jarvis, Peter
Three raw waters of fundamentally different natural organic matter (NOM) character were treated by magnetic resin using a bench-scale method designed to mimic how the resin is used in continuous operation. Increasing water hydrophobicity resulted in reduced dissolved organic carbon (DOC) removal with removal of 56%, 33% and 25% for waters containing 21%, 50% and 75% hydrophobic NOM, respectively. Study of consecutive resin uses showed that the NOM in the hydrophobic water had high affinity for the resin shown by DOC removal of 65% after the first use of the resin. This dropped to 25% DOC removal after 15 consecutive resin uses. For the more hydrophilic waters, NOM removal remained consistent after each resin use. The hydrophobic sample contained higher MW NOM that was capable of blocking resin sites that prevented continual adsorption of organics on to the resin. The hydrophilic NOM containing a large proportion of hydrophilic acids was consistently removed to around 60%. The water containing algogenic-derived NOM was poorly removed by magnetic resin. Subsequent coagulation showed higher removal with increasing hydrophobicity. (C) 2007 Elsevier Ltd, All rights reserved.
Open Access
Measuring Floc Structural Characteristics
(Springer, 2005-05) Jarvis, Peter; Jefferson, Bruce; Parsons, Simon A.
A review is presented of a range of techniques for the structural characterisation of flocs. Flocs may be considered as highly porous aggregates composed of smaller primary particles. The irregular size and shape of flocs makes them difficult to measure and quantify. A range of different equivalent diameters are often used to define the floc size and allow comparison with other floc systems. The application of a range of floc sizing methods has been described. Microscopy is time consuming, requiring large sample size and considerable preparation but gives good information on floc shape and form. Light scattering and transmitted light techniques have been used to good effect to measure floc size on-line whilst individual particle sensors have limited applicability to measuring floc size. Fractal dimension can be measured using one of three major techniques: light scattering, settling and two dimensional (2D) image analysis. Light scattering is ideally suited for small, open flocs of low refractive index whilst settling may be applied to most floc systems of low porosity. 2D image analysis requires flocs to have good contrast between the solid in the floc and the background.
Open Access
Mechanical sludge disintegration for the production of carbon source for biological nutrient removal.
(Elsevier, 2007-04) Kampas, Pantelis; Parsons, Simon A.; Pearce, P.; Ledoux, S.; Vale, P.; Churchley, J.; Cartmell, Elise
The primary driver for a successful biological nutrient removal is the availability of suitable carbon source, mainly in the form of volatile fatty acids (VFA). Several methods have been examined to increase the amount of VFAs in wastewater. This study investigates the mechanism of mechanical disintegration of thickened surplus activated sludge by a deflaker technology for the production of organic matter. This equipment was able to increase the soluble carbon in terms of VFA and soluble chemical oxygen demand (SCOD) with the maximum concentration to be around 850 and 6530 mg l−1, for VFA and SCOD, respectively. The particle size was reduced from 65.5 to 9.3 μm after 15 min of disintegration with the simultaneous release of proteins (1550 mg l−1) and carbohydrates (307 mg l−1) indicating floc disruption and breakage. High performance size exclusion chromatography investigated the disintegrated sludge and confirmed that the deflaker was able to destroy the flocs releasing polymeric substances that are typically found outside of cells. When long disintegration times were applied (10 min or 9000 kJ kg−1 TS of specific energy) smaller molecular size materials were released to the liquid phase, which are considered to be found inside the cells indicating cell lysis.
Open Access
A model for predicting dissolved organic carbon distribution in a reservoir water using fluorescence spectroscopy
(Elsevier Science B.V., Amsterdam., 2004-02-01T00:00:00Z) Goslan, Emma Harriet; Voros, Sandrine; Banks, Jenny; Wilson, Derek; Hillis, Peter; Campbell, Andrew T.; Parsons, Simon A.
A number of water treatment works (WTW) in the north of England (UK) have experienced problems in reducing the dissolved organic carbon (DOC) present in the water to a sufficiently low level. The problems are experienced in autumn/ winter when the colour increases and the coagulant dose at the WTW needs to be increased in order to achieve sufficient colour removal. However, the DOC content of the water varies little throughout the year. To investigate this further, the water was fractionated using resin adsorption techniques into its hydrophobic (fulvic and humic acid fractions) and hydrophilic (acid and non-acid fractions) components. The fractionation process yields useful information on the changing concentration of each fraction but is time consuming and labour intensive. Here, a method of rapidly determining fraction concentration was developed using fluorescence spectroscopy. The model created used synchronous spectra of fractionated material compared against bulk water spectra and predicted the fraction concentrations to within 10% for a specific water. The model was unable to predict fraction concentrations for waters from a different watershed.