Grażyna Totczyk*, Iwona Klugiewicz*, Rafał Pasela*, Łukasz Górski**
*Uniwersytet Technologiczno-Przyrodniczy, Bydgoszcz
**Toruńskie Wodociągi Sp. z o.o., Wyższa Szkoła Zarządzania Środowiskiem, Tuchola
With the treatment of water, especially surface waters, there is produced a high amount of sewage and sludge. They make up a serious ecology problem that due to a high volume and the content of sludge of iron or aluminium oxide-hydroxide or, pollution which occur in the intaken water (mineral and organic substances, algae, protozoa and bacteria) as well as the chemicals added.
The environmental protection requires limiting materials as well as it makes you search for effective waste management problem-solving methods. The waste generated at present during water treatment most often undergo dehydration and drying and then they are deposited at the landfill site. The currently binding environmental protection law makes you look for the possibilities of the use of sludge as recycled materials, e.g. in brick factories, cement factories or with sewage treatment. Sludge containing aluminium or iron can be used e.g. in the process of municipal sewage treatment. The application of sludge containing aluminium for dephosphatation has the advantage of protecting the system from secondary release of precipitated phosphates in the environment deprived of dissolved oxygen. The possibilities of sludge application to remove phosphates differ, depend not only on the sludge characteristics but also on the sewage treatment process.
The article demonstrates the results of research into using sludge derived from water treatment station in Lubicz to remove phosphates from sewage. At present the sludge after sedimentation and mechanical dehydration with the filtration press finally reaches the municipal landfill site.
The sludge, applied for research, concentrated in settling vessels, is a mixture of post-coagulation sludge and washings from anthracite-sand and carbon filters. Its hydration accounting for 98,7% shows a high colour, above 80 mg Pt/dm3, it contains about 2,6 g/dm3 of aluminium as well as organic compounds expressed with BOD5 value equal 170 mg O2/dm3. The sludge shows a high COD of 3990 mg O2/dm3, and organic substance – for 31,6% of dry weight.
The study of effectiveness of the removal of phosphates was made with the vessel test method. The sludge was dispensed at a changing volume from 0,5 to 100 cm3 per 1 dm3 of prepared water and then sewage. Both in water and in sewage there was recorded a 90% removal of phosphates by applying 80 cm3 of sludge per 1 dm3 of the sample. Additionally there was investigated the effect of dispensed sludge on the effectiveness of sewage treatment with the model of the treatment plant with rotating biological contactors. Applying the rate of 40 cm3 of sludge per 1 dm3 produced 96,0% elimination of COD, 97,7% removal of organic compounds characterised with the values of COD and BOD5 as well as 100% removal of phosphates.
Finally it was found that it is possible to use the sludge to remove phosphates from sludge. During dephosphatation there was reported no use-up of the natural alkalinity of sewage. Sludge dispensing did not result in a decrease in the effectiveness of sewage treatment with the method of rotating biological contactors.
The research is preliminary in nature and it needs to be continued.
osady z uzdatniania wody, osady pokoagulacyjne zawierające glin, defosfatacja, TZB, oczyszczalnia ścieków
100. Removal of Phosphates with Post-technological Sludge from Water Treatment Plant
water processing sludge, alumina water processing sludge, dephosphatation, RBC, sewage treatment plant
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Zadanie Czasopismo, Annual Set The Environment Protection Volume 17. Year 2015 (wersja elektroniczna) dofinansowane ze środków Ministerstwa Nauki i Szkolnictwa Wyższego