Preface

Twort, Alan C.; Ratnayaka, Don D.; Brandt, Malcolm J.

doi:10.1016/b978-034072018-9/50000-x

Cited by 29 publications

(53 citation statements)

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“…Polyelectrolytes are eŠective even when they carry a charge the same sign as that of the colloids since ‰occulation aid by polyelectrolytes normally follows charge neutralization or bridging or both (Twort et al, 2000). The larger ‰oc particles settle out more readily under gravity, removing not only the impurities but also most of the chemicals that had been added during the treatment process, producing the homogeneous APC residue byproduct.…”

Section: Role Of Chemical Additives In Formation Of Apc Residuementioning

confidence: 99%

“…When aluminum sulfate solution is intensely mixed into turbid water, various species of positively-charged soluble aluminum hydroxide complexes form due to the reaction between this acidic coagulant and the natural alkalinity of the source water, which usually consists of calcium bicarbonate (Twort et al, 2000). In su‹cient concentration, these mono-and poly-nuclear species adsorb onto the negatively charged colloids through a process of charge neutralization, destabilizing the colloidal suspension so that aluminum hydroxide ‰oc formation and particle aggregation can occur due to par- ticle collisions brought about by Brownian motion.…”

Section: Role Of Chemical Additives In Formation Of Apc Residuementioning

confidence: 99%

“…Dilute polyelectrolyte and aluminum sulfate solutions are commonly used, for example, in the production of potable water by treating naturally occurring water at municipal works. Chemically-assisted sedimentation processes used in water puriˆ-cation reduce suspended solids, color, other soluble materials of organic origin and soluble metals to acceptable levels (Twort et al, 2000). Some are removed directly and some indirectly through attachment or adsorption onto particulate matter.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Aluminum Sulfate and Polyelectrolyte Solutions on the Geotechnical Properties of Organic Clay

O’Kelly

2011

Soils and Foundations

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This paper presents the eŠects of dilute polyelectrolyte solution used in combination with aluminum sulfate on the geotechnical properties of a homogeneous high-plasticity organic clay derived from the puriˆcation of turbid water. Apart from the chemical additives, the alum-polyelectrolyte clay (APC) and untreated clay were similar in composition, comprising 41z micro-ˆbrous amorphous organic solids by dry mass. However, the geomechanical behavior of the APC material was enhanced by polymer-particle bridging phenomenon, which contributed to higher stress-strain modulus, 10-20z greater shear strength in undrained triaxial compression, a higher eŠective angle of shearing resistance value, reduced compressibility and a slower rate of consolidation compared to the untreated clay. Hence, this study raises the possibility of using dilute polyelectrolyte solution in combination with aluminum sulfate as an alternative soil improvement measure for organic residues and ultra-soft organic clay deposits.

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Section: Role Of Chemical Additives In Formation Of Apc Residuementioning

confidence: 99%

Section: Role Of Chemical Additives In Formation Of Apc Residuementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Aluminum Sulfate and Polyelectrolyte Solutions on the Geotechnical Properties of Organic Clay

O’Kelly

2011

Soils and Foundations

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“…Iron is an essential macro nutrient for the normal functioning of all living organisms, hence animal wastes would contain iron. Though iron is beneficial in human diet at low concentrations [26], elevated concentrations produce objectionable reddish-brown colour in the water due to the oxidation of ferrous iron to ferric iron. The concentrations of iron in the samples were generally low with a few exceptions in the months of July and August for the two abattoir sites.…”

Section: Ironmentioning

confidence: 99%

Impact of Urban Livestock Production on Groundwater Quality in Kaduna Metropolis, Nigeria

Kwadzah¹,

Iorhemen²,

Okuofu

2015

AJWR

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Groundwater is the main source of water for most city dwellers in Nigeria. In this study, the impacts of urban livestock production on groundwater quality in Kaduna metropolis were assessed through water quality monitoring. Groundwater samples were collected from wells located around 2 abattoirs (Tudunwada and Kawo abattoirs) and in 8 livestock-keeping households for a 6-month period (July-December). Physico-chemical analyses were conducted on the samples using standard methods. Results indicate that groundwater is negatively impacted in terms of 5-day biochemical oxygen demand, chemical oxygen demand, nitrate-nitrogen, total phosphorus and cadmium; and this impact is of great concern as the values for these parameters are well in excess of established limits. There is negative impact in terms of pH, electrical conductivity, total dissolved solids and zinc but this impact is not a concern as most of the values are within limits. However, no impact was observed on groundwater quality in terms of calcium as it showed no definite pattern of variation. Similarly, iron exhibited very low concentrations in the samples with a few exceptions in the months of July and August for the two abattoir sites. Lead was not detected in any of the samples throughout the study period. This study indicates that livestock keeping and processing activities have negative impact on groundwater quality in Kaduna metropolis. The groundwater pollution due to urban livestock production emanates from point sources and control measures can be easily applied.

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“…Friction, elevation and pressure heads were summed to determine total dynamic head (TDH) required of each well/pump. The service area of each well was determined using reverse-engineering: initially a service area was assumed at a radius of 500 m for each well and the corresponding head losses and frictional losses were estimated using Hazen-Williams equation, with head losses due to elevation calculated by considering the change in elevation of the pipes [40]. We were not able to obtain the make/model of installed pumps, so we chose a suitable candidate pump-Gould ® (Xylem, Inc., Rye Brook, NY, USA) pump model #7TLC 550 GPM-as a surrogate.…”

Section: Modeling Well Service Areasmentioning

confidence: 99%

Integrated Assessment of Shallow-Aquifer Vulnerability to Multiple Contaminants and Drinking-Water Exposure Pathways in Holliston, Massachusetts

Henn

Ogneva‐Himmelberger

Denehy³

et al. 2017

Water

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Half of U.S. drinking water comes from aquifers, and very shallow ones (<20 feet to water table) are especially vulnerable to anthropogenic contamination. We present the case of Holliston, a Boston, Massachusetts suburb that draws its drinking water from very shallow aquifers, and where metals and solvents have been reported in groundwater. Community concerns focus on water discolored by naturally occurring manganese (Mn), despite reports stating regulatory aesthetic compliance. Epidemiologic studies suggest Mn is a potentially toxic element (PTE) for children exposed by the drinking-water pathway at levels near the regulatory aesthetic level. We designed an integrated, community-based project: five sites were profiled for contaminant releases; service areas for wells were modeled; and the capture zone for one vulnerable well was estimated. Manganese, mercury, and trichloroethylene are among 20 contaminants of interest. Findings show that past and/or current exposures to multiple contaminants in drinking water are plausible, satisfying the criteria for complete exposure pathways. This case questions the adequacy of aquifer protection and monitoring regulations, and highlights the need for integrated assessment of multiple contaminants, associated exposures and health risks. It posits that community-researcher partnerships are essential for understanding and solving complex problems.

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Preface

Cited by 29 publications

References 0 publications

Effects of Aluminum Sulfate and Polyelectrolyte Solutions on the Geotechnical Properties of Organic Clay

Effects of Aluminum Sulfate and Polyelectrolyte Solutions on the Geotechnical Properties of Organic Clay

Impact of Urban Livestock Production on Groundwater Quality in Kaduna Metropolis, Nigeria

Integrated Assessment of Shallow-Aquifer Vulnerability to Multiple Contaminants and Drinking-Water Exposure Pathways in Holliston, Massachusetts

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