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Efficiency of aerobic biodegradation of beet molasses vinasse under non-controlled pH : conditions for betaine removal

Ryznar-Luty A., Cibis E., Krzywonos M., Miśkiewicz T.

Archives of Environmental Protection

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2015

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Vol. 41, no. 1

3--14

EN

The aim of the study was to establish such conditions that would provide high-efficiency aerobic biodegradation of beet molasses vinasse with a mixed culture of thermo- and mesophilic bacteria of the genus Bacillus in batch processes without controlling the pH of the medium. Particular consideration was given to the betaine removal (the main pollutant of vinasse), which accounted for as much as 37.6% of total organic carbon. Biodegradation was performed in a stirred tank reactor at 27–63°C with initial pH (pH0) of 6.5 and 8.0. Efficiency of biodegradation was expressed in terms of reduction in SCODsum, which is a sum of SCOD (soluble chemical oxygen demand, i.e. COD determined after suspended solids separation) and theoretical COD of betaine. The values achieved at 27 and 36°C with pH0 = 8.0 exceeded 77.7%, whereas those obtained at 36 and 45°C with pH0 = 6.5 were higher than 83.6%. The high biodegradation effi ciency obtained in the four processes is attributable to the betaine removal by the bacterial strains used in the study. Maximal extent of reduction in SCODsum (85.41%), BOD5 (97.91%) and TOC (86.32%), and also the fastest rate of biodegradation (1.17 g O2/l∙h) was achieved at 36°C and pH0 = 8.0.

PL

Celem pracy było określenie warunków zapewniających wysoką efektywność tlenowej biodegradacji buraczanego wywaru melasowego za pomocą mieszanej kultury termo- i mezofi lnych bakterii z rodzaju Bacillus w procesach okresowych prowadzonych bez regulacji pH podłoża. Główną uwagę poświęcono usunięciu betainy (głównego zanieczyszczenia buraczanego wywaru melasowego). Stanowiła ona aż 37,6% zawartości ogólnego węgla organicznego w biodegradowanym wywarze. Procesy biodegradacji prowadzono w 5-litrowym bioreaktorze z układem mieszania w temperaturze 27–63°C, co 9°C, dla pH początkowego (pH0) równego 6,5 i 8,0. Wysoką efektywność biodegradacji wyrażoną poprzez redukcję SChZTcałk (suma SChZT (ChZT oznaczane po oddzieleniu części stałych) i teoretycznego ChZT betainy) uzyskano w procesach prowadzonych w temperaturze 27 i 36°C dla pH0 = 8,0 (redukcja ponad 77,7%) oraz 36 i 45°C dla pH0 = 6,5 (redukcja ponad 83,6%). Przyczyną wysokiej efektywności biodegradacji w wymienionych czterech procesach było usunięcie przez bakterie betainy. Maksymalny stopień redukcji SChZTcałk (85,41%), BZT5 (97,91%) i OWO (86,32%), jak również największą szybkość biodegradacji (1,17 g O2/l.h) uzyskano w eksperymencie prowadzonym w temperaturze 36°C dla pH0 = 8,0.

2

Influence of process parameters on anaerobic biodegradation of DDT in contaminated soil. Preliminary lab-scale study. Part II. Substrates and pH control

Baczyński T.

Environment Protection Engineering

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2013

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Vol. 39, nr 1

5--16

EN

Suitability of various substrates for anaerobic biodegradation of DDT in contaminated soil was tested in lab-scale tests with granular sludge inoculation. Use of carbohydrate-based substances such as starch, sucrose, molasses and whey resulted in acidification, which in extreme cases inhibited DDT removal. A large amount of phosphate buffer prevented pH drop for starch, but not for sucrose. Better results were obtained with calcium carbonate as a buffering agent, which also had little effect on soil salinity. Very good effectiveness of biodegradation was achieved using sodium lactate which, however, caused alkalinisation of the soil, perhaps due to accumulation of sodium carbonate. Alkalinisation did not occur when calcium lactate was used instead. Experiments also demonstrated that Tween 80 surfactant could be successfully used as a substrate, without experiencing problems with pH control.

3

Influence of process parameters on anaerobic biodegradation of DDT in contaminated soil preliminary lab-scale study. Part I. surfactant and initial contamination level

Baczyński T.

Environment Protection Engineering

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2012

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Vol. 38, nr 4

113--125

EN

Anaerobic biodegradation of DDT in field-polluted soil was investigated in relation to Tween 80 surfactant dose and initial pollution level. Experiments were carried out as lab-scale tests with flooded soil, inoculated with granular sludge. Higher surfactant doses decreased DDT residual concentration and also reduced DDD metabolite accumulation. However, doses higher than optimum caused DDD production to increase again. Results were also better for lower initial contamination levels - DDD accumulation was smaller whereas formation of terminal metabolite DBP was higher, indicating an enhancement of DDT transformation. Tests with pure compounds spiked in clean soil demonstrated that DDD is degraded slowly. Results point to three possible parallel pathways of anaerobic DDT transformation, not, as commonly reported, only one starting with dechlorination to DDD.