Sewage Treatment Plant

Les boues de station d'épuration sont constituées de sédiments résiduaires issus des traitements des eaux usées. En France, chaque habitant génère environ 50 g de matières sèches de boues par jour et ces résidus représentent environ 850 000 t de matières sèches par an. Actuellement, 60% des boues de station d'épuration produites en France sont épandues en agriculture alors que 20 à 25% sont mises en décharges et 15 à 20% sont incinérées. L'impact de la politique européenne en matière de traitement des eaux usées se traduit par une augmentation de la production des boues qui dépasserait, en France, un million de tonnes de matières sèches en 2005. Dans ce contexte général d'augmentation des quantités de boues, d'une part, et devant l'abandon progressif de la mise en décharge des déchets non ultimes, d’autre part, on voit difficilement comment la part de l'épandage pourrait diminuer. Cependant, la controverse qui s'est développée au cours des dernières a...

Zeekoevlei is the largest freshwater lake in
South Africa and has a century-long history of
anthropogenic impact that caused hyper-eutrophic
conditions. We used biomarkers (alkanes and pigments),
stable isotopes (d13C and d15N), rates of
primary palaeoproduction and total inorganic carbon
(TIC) accumulation rates in the lake sediments to
investigate changes in plankton and macrophyte
communities in response to anthropogenic activities
in this shallow lake. Specific alkanes and pigment
(chlorophyll a, b,b-carotene, echinenone, fucoxanthin
and zeaxanthin) concentrations in lake waters indicated
the present-day hyper-eutrophic condition and
seasonal fluctuations of cyanobacteria, zooplankton
and diatom populations. Eutrophic conditions were
initiated in the lake with the start of recreational
activities and construction of a sewage treatment plant
in the early 1920s. The lake transformed from a
eutrophic to a hyper-eutrophic waterbody following
damming, pondweed eradication and accelerated
catchment-derived nutrient input. The change in lake
trophic state was recorded by a sharp decline in the
terrestrial to aquatic ratio (TAR) of specific n-alkanes,
low carbon preference index (CPI) and increased d13C
values in the sediment core. In addition, the aquatic
macrophyte n-alkane proxy (Paq) values (1) indicated
a slow takeover by floating macrophytes after
the eradication of submerged pondweeds in 1951.
Elevated n-alkane, total alkane and pigment
(chlorophyll a, b,b-carotene, zeaxanthin and
zeaxanthin to b,b-carotene ratio) concentrations, low
d15N values and low TIC accumulation rates in the
upper middle section of the core indicated the
beginning of intense cyanobacterial blooms after the
dredging in 1983. Although the cyanobacterial population
has decreased in recent years, hyper-eutrophic
conditions are reflected by low CPI<0.04 and TAR<1
values at the top of the sediment core.

Composting is an alternative for recycling agricultural residues and sewage sludge, and the end pro- duct can be used as fertilizer for land application. In order to study the composting process with sludge from water sewage treatment plants and rice straw, environmental factors should be controlled. The aim of our study was to investigate the optimum C/N ratio, moisture and pH to maximize microbial activity. The incubation of sewage sludge and rice straw mixtures were conducted using an experiment design with three different C/N ratios (17, 24 and 41), moistures (40, 60 and 70 %) and pH (5.65, 6.65 and 8.75). The micro- bial activity was measured as manometric measurement of oxygen consumption. The enhancement of microbial activity is induced by low C/N ratio, high moisture content, and pH basic. Our results suggest that the initial blend with these raw materials must be about 17 C/N ratio, while moisture content must be between 60 % and the pH 8.75 in the composting process.

The recent monitoring of drug residues in the aquatic environment has gained much interest as many pharmaceutical compounds can frequently be found in sewage treatment plant (STP) effluents and river water at concentrations up to several microgram/l. This article describes the analysis of various water samples for 18 antibiotic substances, from the classes of macrolid antibiotics, sulfonamides, penicillins and tetracyclines. Samples were preconcentrated via lyophilization and quantified using HPLC-electrospray-tandem-mass spectrometry. The investigated STP effluents and surface water samples showed frequent appearance of an erythromycin degradation product, roxithromycin and sulfamethoxazole with concentrations up to 6 micrograms/l. Neither tetracyclines nor penicillins could be detected at concentration levels above 50 and 20 ng/l, respectively. From the large number of ground water samples that were taken from agricultural areas in Germany, no contamination by antibiotics was dete...

Sewage treatment plant (STP) operators are exposed to variety of hazard during wastewater processing. The aim of this study is to identify and manage these hazards, particularly in a local STP in Malaysia, through Occupational Health and Safety Management System (OSHMS). Initially, reported hazards data were collected via review of literatures, questionnaire distribution and interview with experts. Then, the most risky hazards based on conditions of selected STP were identified. Subsequently, the hazards were ranked based on severity and likelihood. Results show exposure to excessive noise, skin irritation and slip and fall are the main concerns of workers in the site. Therefore, noise mitigation was done using sound absorbers. It was indicated that the level of existing noise (94.2 dB) was reduced to 92.1 dB and 90.6 dB by application of carpet and cardboard, respectively. Skin irritation risk is suggested to be mitigated by installation of auto-cleaner, self-cleaning bar screen and scraper blades at the site. In addition, cordoning off areas while cleaning is in progress and provision of ramps at cleaning area around the clarifier are found to be the appropriate solutions for slip and fall risk at the site.

The Phytorid Technology is a combination of the physical, chemical and biological processes in which resulted into ultimate treatment for the waste water. This method is more advantageous of cost effective, minimum operations and maintenance. The main objective of the project is to make green treatment system as economical as possible. It treats the sewage in natural manner using some special types of plants. The Phytorid system of wastewater management has get a lot of importance in recent times. We analyse, design, estimation and valuation of treatment plant in this project. The present analysis and design work were undertaken by our team and designed for academic building of Dr. Babasaheb Ambedkar Technological University, Lonere.

This report represents a concise account of the experience I acquired on the various machines, equipment’s and laboratory procedures together with plant process during this period of attachment at the Alscon Township water Treatment Plant Facility 78 in Ikot Abasi.

The research focused on the management of stormwater and sewage generated in a
developed urban area - Federal University of Technology, Akure, Ondo State, Nigeria. This involved the design of sanitary sewers, stormwater collection networks and a central sewage treatment plant. The total estimate of the wastewater generated from various locations was 5.067 million litres per day based on the population of approximately 26,131. The existing sewage disposal system in use in the institution was the septic tank-soakaway arrangement for individual buildings. The design of the sanitary sewers and stormwater collection networks are based on the principles of hydraulics. The results obtained were used to analyze and design the drains and pipe sizes for the open channels and the closed conduits respectively. The size of the drains for stormwater collection networks was designed with the assumption of 0.75 and 1 meter width. Also, calculations were made for square drain (depth equals width)
to be able to select practicable sizes. For optimum size solution, pipe size of 100 mm was found to be suitable for wastewater conveyance from the office areas. The sizes of pipes calculated for flows from residential quarters are too small, hence available commercial pipe sizes were selected. Wastewater samples were collected at various locations and were determined through laboratory tests to ascertain the concentrations of significant physical, chemical and biological content of the wastewater for proper selection of appropriate treatment processes. A BOD concentration of 350 mg/l and 353 mg/l obtained for residential and office areas respectively translated to high pollution load requires treatment before ultimate discharge into the receiving stream. The proposed sewage treatment plant was sited
at the lowest topographical level, far enough from the office and residential quarters. This would allow flow by gravity from the various points. The sewage treatment plant components selected include screen chamber, grit chamber, skimming tank and rectangular/circular primary settling/sedimentation tank (PST), which are designed to optimal dimensions.

The presence of bioactive trace pollutants such as pharmaceuticals and ingredients of personal care products (PPCPs) in different environmental compartments (rivers, lakes, groundwaters, sediments, etc.) is an emerging issue due to the lack of existing information about the potential impact associated with their occurrence, fate and ecotoxicological effects. Due to the low PPCP concentrations reported in wastewaters (ppb or ppt) and their complex chemical structure, common technologies used in sewage and drinking water treatment plants may not be efficient enough to accomplish their complete removal. Information about physico-chemical characteristics such as acidity, lipophilicity, volatility and sorption potential is a useful tool to understand the different removal patterns observed. In order to perform an accurate overall mass balance along the different units of sewage treatment plants, it is necessary to gather information not only about the presence of micropollutants in the aqueous phase, but also on the fraction sorbed onto solids. Since only some PPCPs are very well eliminated by conventional sewage treatment configurations, new strategies such as modification of operating conditions (e.g. solids retention time), implementation of new technologies (e.g. biomembrane reactors) or additional advanced post-treatment steps (e.g. oxidation, adsorption, membranes) have been suggested for an increased efficiency.