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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

2013

Vol. 39, nr 1

5--16

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.

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

2012

Vol. 38, nr 4

113--125

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.