Anaerobic biotransformation of organo-arsenical pesticides monomethylarsonic acid and dimethylarsinic acid.

Monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) are extensively utilized as pesticides, introducing large quantities of arsenic into the environment. Once released into the environment, these organo-arsenicals are subject to microbial reactions. Aerobic biodegradation of MMAV and DMAV has been evaluated, but little is known about their fate in anaerobic environments.

Methanogenic inhibition by arsenic compounds.

The acute acetoclastic methanogenic inhibition of several inorganic and organic arsenicals was assayed. Trivalent species, i.e.

Thermal and enzymatic pretreatment of sludge containing phthalate esters prior to mesophilic anaerobic digestion.

The present study aimed at investigating the effect of thermal pretreatment of sludge at 70 degrees C on the anaerobic degradation of three commonly found phthalic acid esters (PAE): di-ethyl phthalate (DEP), di-butyl phthalate (DBP), and di-ethylhexyl phthalate (DEHP). Also, the enzymatic treatment at 28 degrees C with a commercial lipase was studied as a way to enhance PAE removal. Pretreatment at 70 degrees C of the sludge containing PAE negatively influenced the anaerobic biodegradability of phthalate esters at 37 degrees C.

Mesophilic and thermophilic anaerobic digestion of primary and secondary sludge. Effect of pre-treatment at elevated temperature.

Anaerobic digestion is an appropriate technique for the treatment of sludge before final disposal and it is employed worldwide as the oldest and most important process for sludge stabilization. In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization, enhancement of dewatering of the sludge, reduction of the numbers of pathogens and could be realized at relatively low cost especially at low temperatures.