Evaluating of the disinfection and water quality effects on UV application in the primary stage of water treatment

Background: Irradiation of water by UV has been considered as an attractive alternative for disinfection because its low-impact, pathogen killing capacity shows tremendous promise for meeting today's drinking water regulatory requirements. This study has been performed with the objective of utilizing medium pressure lamp in the preliminary stage of municipal water treatment, namely prior to water clarification and filtration. Methods: Raw water samples were irradiated for 30 s in a lab-scale closed reactor. Disinfection results showed nearly 2 log reduction in HPC for all the samples without formation of nitrite in excess of its MCL. As in a few previous works the formation of nitrite as an objectionable DBP had been reported, this study was extended by preparing synthetic water samples having different amounts of nitrate and turbidities. Results: As far as the initial nitrate concentration dose not exceed 10 mg/L N-NO3, there would be no risk of nitrite increasing in excess of the MCL. Conclusion: Meeting the goal of at least 90 % disinfection for water samples with turbidity levels of as high as 750 NTU is possible by utilizing medium- pressure UV lamp

The Effectiveness of a Contact Filter for the Removal of Iron from Ground Water

Various types of modified filters were investigated to replace greensand filters which clogged when removing ground water. A properly designed uniform-grain sized filter can increase the filtration time more than ten times that of ordinary sand or greensand filters. The filter medium was obtained by passing commercial filter material between two standard sieves of a close size range, so that the resulting medium was of a uniform size. The head loss rate on such a medium was independent of the filter depth and was inversely proportional to the almost 3/2 power of the grain size. On the other hand, the filter depth was almost linearly proportional to the time of protective action. The effects of the grain size, filter depth, and filter material on the filter run were evaluated with a synthetic iron water; and optimum filter depths for each unisized material were determined. At identical filtration conditions, anthracite had a 70 to 110% longer filter run than the sand medium, and it was attributed to the greater porosity of the former. Expectedly, the time to reach initial leakage of the iron floc was greater with the coarse and more porous medium. but was reduced to an insignificant amount when the filter depth was increased to three to six feet. The performance of unisized filters on permanganate-treated ground water was much better than that of fine-grained greensand. Applicability of experimental data on an existing filtration theory was investigatedThe work upon which this report is based was supported by funds (Proj. A-025-ALAS) provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Act of 1964

Performance of hydrailic coagulation and flocculation of sg kampar water treatment plant

The objective of the study is to assess the influent of physical and other variables such as flow rate, temperature, dosage of alum and pH on the performance of hydraulic coagulation and flocculation of Sg. Kampar Water Treatment Plant

Formation of halogenated organic byproducts using preoxidation with chlorine, ozone and peroxone and post-chlorination of water containing humic substances

Dentre os compostos orgânicos halogenados que podem ser encontrados na água distribuída à população, destacam-se: trialometanos, ácidos haloacéticos, haloaldeídos, halocetonas, halofenóis e halopicrinas. O presente trabalho teve como objetivo avaliar o efeito da formação de 22 subprodutos com a utilização dos pré-oxidantes: cloro, ozônio e peroxônio. A formação de subprodutos foi observada em água preparada com adição de substâncias húmicas extraídas de solo turfoso, por meio do uso da pré-oxidação, presença e ausência de coagulação, filtração e pós-cloração. Os subprodutos foram quantificados por cromatografia gasosa com detetor de captura de elétrons. Os resultados obtidos mostraram que o uso de pré-oxidantes alternativos, ozônio e peroxônio, associados à coagulação, filtração e pós-cloração, formam quantidades pequenas de subprodutos.When chlorine is used as preoxidant, the formation of halogenated organic byproducts found in water treated and distriduted to the population, are: trihalometane, haloacetic acids, haloaldehyde, haloketone, halophenol and halopicrin. This research was performed to evaluate the formation potential of 22 byproducts using the following preoxidants: chlorine, ozone and peroxone. The formation of byproducts was simulated in water prepared with the addition of humic substances extracted from peat soil by the use of preoxidants, coagulation, filtration, and post-chlorination. Byproducts have quantified by gas chromatography with electron capture detector. The results obtained showed that the use of alternative preoxidants, such as ozone and peroxone, associated with coagulation, filtration, and post-chlorination form a low concentration of byproducts.FAPES

Geotechnical and environmental problems related to shales in the Abakaliki area, Southeastern Nigeria

Six (6) samples of shale and five (5) water samples from hand-dug wells and boreholes, from different locations within the Abakaliki shale formation, have been assessed to evaluate the impact of the shale formation to the geotechnical and hydrogeo-environmental problems prevalent in the Abakaliki area (Southeastern Nigeria). Results indicated that the shale samples have Atterberg limits that might be considered moderate to high; while Liquid Limit (LL) ranged from 49 – 54, the Plasticity Index (PI) ranged from 34 – 38. These relatively high LL and PI suggested presence of expansive clays, some swelling of the shale on moisture influx and high compressibility. Natural moisture content (with mean value of 20%) was also significantly high. Hydrochemical analyses, on the other hand, revealed that the water samples had comparatively high content of ions and dissolved particles; Ca2+ ranged from 8.0 – 134.0 mg/l, Mg2+ ranged from 0.2 – 3.3 mg/l, HCO-3 ranged from 21.8 – 1176.1 mg/l and total dissolved solids ranged 56.9 – 1415.0 mg/l. Dissolution of soluble minerals (predominantly calcite and other rock salts) contained in the shale might likely be responsible for the release of these particles. Geotechnical behaviours of the shale and hydrogeochemical characteristics of water samples from the shale formation, thus, provided insights into the probable causes of seasonal waterlogging, consistent poor groundwater quantity and quality, structural and foundation problems that are prevalent in the Abakaliki area.Key words: Abakaliki shale, dissolution, environmental problems, geotechnical analysis, groundwater quality, structural failure

Determination of Trace Metals Quality of Sources of Drinking Water in Some Selected Communities in the Akuapem South District of the Eastern Region, Ghana

The study was undertaken in three communities namely Adamrobe, Aburi and Pokrom-Nsaba, all located in the Akuapim South District of the Eastern Region. These communities depend on streams, wells, and springs for their drinking water requirements. The objective of the study was to assess the trace metals quality of the drinking water sources used by the communities. Water samples from these sources (streams, wells, and springs) were analyzed over a period of twelve months for various water quality parameters including the following trace metals: lead (Pb), cadmium (Cd), zinc (Zn), & arsenic (As), following standard methods designed in APHA, AWWA, and WEF. The results of the study revealed that, most of the mean levels of trace metals registered from the water samples were below the World Health Organization (WHO) and Ghana Water Company Limited (GWCL) recommended critical limits for drinking water standards. The low level of trace metals recorded in the water samples was due to the absence of industrial and mining activities in these communities and their environs. The high level of lead registered in ABSP was as a result of the low pH discovered in the water sample for that station. It is therefore recommended that further study be conducted to track the long term health effects of the trace metals in the drinking water sources used by the study communities. Keywords: Trace Metals Quality, Sources of Drinking Water, Selected Communities, Akuapem South District, Eastern Region, Ghana

Dynamic Growth Rates of Microbial Populations in Activated Sludge Systems

Results of mathematical modeling and whole cell 16S ribosomal RNA-targeted fluorescence in situ hybridizations challenge the widely held perception that microbial populations in steady-state activated sludge systems share a common net growth rate that is proportional to the inverse of the mean cell residence time. Our results are significant because they encourage bioprocess engineers to appreciate the differences in growth physiology among individual microbial populations in complex mixed microbial communities such as suspended growth activated sludge bioreactor systems

Air-Water Mass Transfer on a Stepped Waterway

Stepped waterways are commonly used as river training, debris dam structures, storm water systems and aeration cascades. The present study was focused on analysis of basic air-water flow properties on a low gradient stepped chute, combined with dissolved oxygen measurements. The oxygen aeration efficiency was found to be about 30% for 12 steps with a total drop in invert elevation of 1.4 m, nearly independently of the inflow conditions. Detailed air-water flow measurements, including void fraction, velocity, bubble count rate and interface area, were used to integrate the mass transfer equation and to estimate the aeration potential of the waterway. Direct comparisons with dissolved oxygen measurements showed good agreement between the two methods

Influence of temperature on the performance of a full-scale activated sludge process operated at varying solids retention times whilst treating municipal sewage

In this study, the solid retention time (SRT) was varied with the ambient temperature for a full-scale municipal activated sludge plant with capacity of 200,000 PE (Population Equivalent) located in a humid sub-tropical environment. The effects of ambient temperature on treatment performance were investigated. Off-line samples were collected and analyzed from the treatment plant. The actual temperature variation during the study period was divided into three overlapping ranges and the SRT was adjusted accordingly with temperature in order to achieve the desired effluent quality. The plant’s observed effluent quality and thereby its overall removal efficiency was evaluated in terms of measuring standard biochemical parameters. The results indicate that significant improvement in effluent quality can be obtained by applying the variable SRT (5–7 days) dependent on temperature variation

Near shore beach volume modeling approach for setting beach bacteria TMDLs: A case study, Hickory Grove Lake, Iowa

A novel approach to set bacteria Total Maximum Daily Load (TMDL) using a Near-Shore Beach Volume (NSBV) model was described along with recommendations for design of a monitoring network to support this method. Sources of fecal bacteria in the Hickory Grove Lake watershed include unpermitted septic systems, manure applications in the watershed, livestock access to streams, waterfowl, and wildlife. The Lake Inlet, Lake Outlet, and Lake Beach were monitored for E. coli concentrations from 2010-2012, this monitoring data was used to assess relationships between watershed bacteria loads and the beach bacteria levels. Fecal bacteria from waterfowl were identified as the major source to the Lake Beach causing the water quality impairment. The bacteria TMDL for the Hickory Grove Lake beach was set at 1.87E+11 orgs/day for the single sample maximum target and 1.01E+11 orgs/day for the geometric mean target, which correlates to the presence of fewer than five resident geese. Monitoring recommendations to support this approach include weekly beach water quality monitoring and post-event sampling; periodic spatial sampling of the lake; weekly and post-event grab sampling of the water quality at the lake inlet mixing zones; and weekly and post-event grab sampling of the water quality at the lake outlet