Soil, biological treatment

Figure 14. UV monitoring of a petroleum hydrocarbon soil biological treatment.

Health nd SMety Factors. The lowest pubhshed human oral toxic dose is 430 mg/kg, causing nervous system disturbances and gastrointestinal symptoms. The LD q (rat, oral) is 750 mg/kg (183). Thiocyanates are destroyed readily by soil bacteria and by biological treatment systems in which the organisms become acclimatized to thiocyanate. Pyrolysis products and combustion products can include toxic hydrogen cyanide, hydrogen sulfide, sulfur oxides, and nitrogen oxides. 

Biological treatment processes can be used to treat organic contaminants in liquid, slurry, and soil matrices. However, it should be remembered that moisture is an essential need of the biomass both for... 

Cassidy DP, RL Irvine (1997) Biological treatment of a soil contaminated with diesel fuel using periodically operated slurry and solid phase reactors. Water Sci Technol 35(1) 185-192. 

Comparison of the Removal of PAHs from Contaminated Soil by Conventional Biological Treatment, or by Combined Biological and Chemical Treatment... 

Lenke H, 1 Warrelmann, G Dann, K Hnnd, U Sieglen, U Walter, H-1 Knackmuss (1998) Biological treatment of TNT-contaminated soil. 2. Biologically induced immobilization of the contaminants and fnll-scale application. Environ Sci Technol 32 1964-1971. 

In cases where in situ biological treatment cannot be applied, the contaminated soil is excavated and transferred to specially prepared areas where bioremediation can be carried out under well-controlled conditions. Some common ex situ biological methods are the landfarming technique and the biopile or biopit treatment options.32... 

Other factors affecting performance include the presence of toxic material, the redox potential, salinity of the groundwater, light intensity, hydraulic conductivity of the soil, and osmotic potential. The rate of biological treatment is higher for more permeable soils or aquifers. Bioremediation is not applicable to soils with very low permeability, because it would take a long time for the cleanup process unless many more wells were installed, thus raising the cost. 

The technology for in situ biological treatment for soil is similar to that for in situ biological ground-water treatment. The following sections present three newly developed techniques. 

Ex Situ Biological Treatment on Excavated Soil by Slurry Biodegradation... 

Seech, A.G., J.T. Trevors, and T.L. Bulman. 1991. Biodegradation of pentachlorophenol in soil the response to physical, chemical, and biological treatments. Canad. Jour. Microbiol. 37 440-444. 

Biological treatment systems do not handle shock loads well. That probably won t be a problem because you are dealing with a soil system and not a liquid system, but the principles are the same. It will take longer and substantially more work to degrade higher eoneentrations of materials in the soils. 

Thom and Agg (1975) reported that diuron is amenable to biological treatment with acclimation. Soil Several degradation pathways were reported. The major products and reaction pathways include formation of l-methyl-3-(3,4-dichlorophenyl)urea and 3-(3,4-dichlorophenyl)urea via Wdealkylation, a 6-hydroxy derivative via ring hydroxylation, and formation of 3,4-dichloroaniline, 3,4-dichloronitroaniline, and 3,4-dichloronitrobenzene via hydrolysis and oxidation (Geissbiihler et al, 1975). 

It has been estimated that over 400,000 m of dilute waste pesticide solution are generated In the United States annually ( 1 ). While the bulk of these waste solutions are used legally as spray diluent, some are disposed of by chemical or biological treatment, Incineration, or In soil pits and evaporation ponds (1-3). 

Mayabhate, S.P. Gupta, S.K. Joshi, S.G. Biological treatment of pharmaceutical wastewater. Water Air Soil. Poll. 1988, 38, 189-197. 

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