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Neutralizacja nieprzyjemnych zapachów powstających podczas odwadniania komunalnych osadów ściekowych w procesie sedymentacji odśrodkowej

Kowalczyk A., Kutryn J., Piecuch T.

Rocznik Ochrona Środowiska

2010

Tom 12

365-380

Z chwilą wejścia Polski do Unii Europejskiej w maju 2004 r. w naszym kraju zaczęły obowiązywać standardy i normy europejskie m.in. w zakresie ochrony środowiska. Jednym z elementów wymagających jeszcze uregulowania, jest emisja do środowiska nieprzyjemnych zapachów w wyniku funkcjonowania takich obiektów jak: składowiska odpadów, zakłady ich utylizacji, oczyszczalnie ścieków, fermy hodowlane czy zakłady przemysłowe. Emisja tych nieprzyjemnych zapachów stanowi dużą uciążliwość zarówno dla pracowników zakładów jak i mieszkańców okolic. Bliska konieczność opracowania polskich norm w zakresie metod oceny intensywności odorów, a także przepisów określających ich oddziaływanie na środowisko, przyczynia się do podejmowania badań nad odorami w zespołach badawczych różnych instytucji (zespoły badawcze m.in. [1, 3÷6, 9÷18]). W wypadku niewielkich emisji, gdy stężenia odorantów są małe, a mimo niskich progów wyczuwalności zapachowej powodują istotną uciążliwość, możliwe jest stosowanie środków maskujących [1, 9÷18].

Emission of unpleasant odours is noxious for both plant workers and residents of surrounding areas, where odours are emitted. In the case of low emissions, the concentration of odour substances are low, and despite of the low odour detection thresholds, they cause significant noxiousness, it is possible to use masking agents. This issue is within range of interest of Division of Water-Sludge Technology and Waste Utilisation of Koszalin University of Technology, where for a few years works are conducted on production of an effective and inexpensive agent for decreasing nuisance of odours. Natural essential oils extracted from fresh plant materials in the process of steam distillation are used as masking agents. The aim of this study was to present a method of reduction of odour nuisance during dewatering of municipal sewage sludge by dosage of the essential oil to sewage sludge. esearch on the use of essential oils for masking of odours were divided into two stages. In the first stage of the research essential oil of lemon in the process of steam distillation was produced. Then, produced oil was used in the second stage of research as an agent for masking odour during municipal sewage sludge dewatering. Sludge dewatering process was carried out on a laboratory centrifuge MPW 350. As a input to dewatering process a real stabilized in the process methane fermentation sludge was used, taken from the Wastewater Treatment Plant Jamno, directly from the pump pipe connecting fermentation tanks with centrifuges. Constant parameters of centrifugal sedimentation were: rotation time t [min.] (assumed centrifugation time t = 1 min.) and rotation speed n [rpm] (assumed n = 2400 rpm). Independent variable process parameters were: dose of flocculant C [kg/Mg of dry mass] and dose of essential oil D [cm3/100 cm3 of sludge]. Essential oil, which was produced from lemon was dosed to the feed (sewage sludge with flocculant) before dewatering process in four doses: D\ = 0 cm3 of oil/100 cm3 of sludge, D2 = 2 drops of oil = 0.06 cm3/100 cm3 of sludge, D3 = 4 drops of essential oil = 0.12 cm3/100 cm3 of sludge and D4 = 6 drops of essential oil = 0.18 cmVlOO cm3 of sludge and then period of time of essential oil smell lasts in eluate and sludge after centrifugation process was examined. The study showed that the essential oil of lemon effectively neutralizes odours of sludge and eluate, produced during dewatering of municipal sewage sludge on the laboratory sedimentation centrifuge. With an increasing dose of essential oil of lemon, time of neutralisation of odours after dewatering is increasing, both for the dewatered sludge and eluate. It was also found that essential oils as hydrophobic substances have additional function of coagulants or flocculants, and improve the quality of the mechanical dewatering.

Odwadnianie komunalnych osadów ściekowych na laboratoryjnej wirówce sedymentacyjnej typu MPW-350 oraz na przemysłowej wirówce typu Noxon DC20 - problem przeniesienia skali

Kutryn J., Piecuch T.

Rocznik Ochrona Środowiska

2009

Tom 11

517-542

The paper presents results of municipal from Jamno Wastewater Treatment Plant (JWTP) dewatering, through whirling in laboratory centrifuge MPW- 350 and industrial Noxon DC20 centrifuge, made in Sweden with operating efficiency 8-25 m3/h. The examinations has been conducted within parameters range: whirling time 1 to 10 min, rotation speed 1800÷2400 1/min, flocculent dose: 0, 28, 34 ml/dm3 (only laboratory centrifuge). Discussed issue was difference of water content value of sediment W% after whirling in laboratory centrifuge MPW-350 and in industrial Nixon centrifuge. The effect of whirling of the same sludge in laboratory centrifuge MPW-350 and industrial Noxon centrifuge, assuming the same whirling time, rotation speed, was better for industrial centrifuge. Better effect of municipal sewage sludge dewatering in industrial centrifuge was a result of centrifugal force value, main dewatering force, which determines the centrifugal sedimentation pressure.The realization of investigative evaluations for the industry related with mechanicaldewatering of sediments in the field of centrifugal forces is not enough for objective assessment of sediments whirling efficiency only on the basis of the opinion of tests in laboratory conditions, when the result of such evaluation is application (e.g. purchase and the use of industrial centrifuge). Utilisation of laboratory examinations on mechanical dewatering of sediments in the field of centrifugal forces can only be useful for the practice, when there are directives relating to so-called transfer of scale of investigations, or also prediction based on such investigations, which was introduced in the paper. If it is possible to conduct investigations in the industrial scale for given sediments in order to apply results (purchase and application), then they should be conducted for the correct assessment of dewatering efficiency. Investigations described in the paper show that the difference of water kontent in sediments after dewatering process in the industrial centrifuge, in comparison to dewatering process in laboratory centrifuge, is the result of the pressure inside the industrial centrifuge 5-6 times higher than pressure inside the laboratory centrifuge; this obviously also depends on the sequence of other parameters characterizing the process, which answers with those assumptions, quotient of pressure.