Suchergebnisse

AbstractIn the UK, the disposal of wastes from the production of potable water has been an increasing problem for water companies since the introduction of the Waste Management Licensing Regulations in 1994. This paper considers alternative management strategies. The importance of investigating each works individually is stressed because of variations in sludge properties and disposal costs. Of the disposal options, the growing of turf is environmentally sustainable and economically attractive, whereas direct spreading on agricultural land and use in soil production can be successful. Other uses, e.g. in ceramics, are at various stages of development; co‐disposal with sewage is an option, but hidden costs need to be assessed.

ABSTRACTThe performance of treatment processes is reviewed for the removal of five potential water contaminants, i.e. pesticides; volatile organic solvents; nitrates; Cryptosporidium oocysts; and Giardia cysts.Technologies for organic solvents and nitrate removal are well advanced and in operation. Adsorption on activated carbon is available for pesticides removal, but more information is required to assist in selection and operation; new processes are also required. Physicochemical treatment can remove Giardia, but optimization and control are critical factors. Unfortunately little is known about Cryptosporidium removal. Ozone is more effective than chlorine for inactivating both Cryptosporidium and Giardia that have penetrated the treatment train.

There are presented results of technological experiments carried out in Water Treatment Plant Kúty. The goal of this study was to compare modified zeolite known as clinoptilolite (rich deposits of clinoptilolite were found in the region of East Slovakia in the 1980s) with the imported modified zeolite from deposit situated in Hungary. Klinopur-Mn and Klinomangan were used for removal of iron and manganese from ground water to meet the requirements of the Regulation of the Government of the Slovak Republic No. 496/2010 on Drinking Water. The materials observed exhibit different efficiencies of manganese removal from water, since the quality of the treated water play a major role (oxygen content and pH value). In the case of the removal of the iron from the water, the quality of the raw water is not a limiting factor; both materials removed Fe from the water to below the limit value (0.20 mg.l-1). ; Článok prezentuje výsledky technologických skúšok vykonaných v UV Kúty. Cieľom tejto práce bolo porovnať modifikované (povrchovo upravené) zeolity známe ako klinoptilolit (veľké nálezisko klinoptilolitu bolo objavené na Východnom Slovensku v 1980-tych rokoch) s dovážaným povrchovo upraveným zeolitom z náleziska v Maďarsku. Klinopur-Mn a Klinomangan boli použité pre odstraňovanie železa a mangánu z podzemnej vody na dosiahnutie limitných hodnôt pre pitnú vodu podľa Nariadenia vlády č. 496/2010 Z.z. Sledované materiály vykazovali rôznu účinnosť odstraňovania mangánu z vody, na účinnosť odstraňovania mala významný vplyv kvalita upravovanej vody (obsah kyslíka, hodnota pH). V prípade odstraňovania železa z vody kvalita surovej vody nie je limitujúcim faktorom, obidva materiály odstraňovali železo z vody pod limitnú hodnotu (0,2 mg.l-1).

Aluminum sulfate and polyaluminum chloride are widely used as coagulants in water treatment plants. A chemical sludge containing aluminium hydroxide, adsorbed organic matter and other water insoluble impurities is obtained after the flocculation-clarification process. In Portugal, an estimated amount of 66 000 ton/yr. (wet wt.) water treatment sludge is being disposed of on land or at municipal solid waste (MSW) landfills. Government restrictions to this practice as well as increasing deposition costs and the potential harmful impacts proceeding from the high aluminium content of the sludge have been leading to significant research efforts in order to evaluate different treatment alternatives, namely involving aluminium recovery and subsequent reuse. Despite membrane-based separation and liquid ion ex-change processes have been studied for that purpose, the traditional acidic and alkaline extraction methods may be still explored to obtain a product susceptible of use as coagulant for industrial waste-water treatment purposes. Centrifuged chemical sludge from a water treatment plant using polyaluminium chloride as coagulant was characterised in terms of humidity, volatile matter, Al, Fe, Mn, Cd, Cu, Cr, Pb, Ni and Zn. The dry sludge organic content is about 29% and the major elements determined are aluminium (~ 12.6%), iron (~ 2%) and manganese (~ 0.14%). The aluminium recovery was investigated both by acidic and alkaline leaching processes. Concentrated H2SO4 was selected as the acidic leaching medium and the process efficiency was evaluated at different operating conditions. The ratio dry sludge/sulphuric acid solution was varied between 0.5 and 2%, the pH ranged from 1.0 to 4.5, different stirring and settling times were established and the aluminium, iron and manganese dissolution was assessed. A similar study was performed at pH values between 10.0 and 13.6 using 2N/10N NaOH as the extracting solution and operating conditions as those of the acid extraction procedure. Whereas maximum alu-minium recovery ...

AbstractAlum recovery from water treatment sludge is a promising technique applied for reducing the virgin coagulant demand and the sludge volume and safe disposal of the sludge. The aim of the current study is to optimize alum recovery process from alum sludge in Samannoud water treatment plant, Egypt by acidification technique using sulphuric acid and evaluate the effect of total solids (TS) content in the sludge on alum recovery process. Results showed that the optimal mixing time for alum recovery was 60 min for clariflocculator sludge, whereas 15 min for thickener sludge. Optimum pH value was 1.50 for alum recovery from different sludge types. At optimum conditions, acidification experiments showed that alum recovery percent and sludge volume reduction for clariflocculator sludge were 83 and 91.2%, respectively, versus 35.9 and 45%, respectively, for thickener sludge. Besides, alum recovery and sludge reduction decreased with the increase in TS content in the sludge.

ABSTRACTSevern Trent Water is currently undertaking an extensive capital programme to enhance water‐treatment facilities at many of its major plants, and this work is underpinned by the need to apply robust, cost‐effective solutions utilizing modern treatment technology.The paper describes various aspects in the development of these functional designs in relation to treatment objectives, technical innovation and value engineering, drawing examples from Severn Trent schemes and particularly from the redevelopment of the Birmingham water‐treatment plant.