Methanogenic inhibition by roxarsone (4-hydroxy-3-nitrophenylarsonic acid) and related aromatic arsenic compounds.

Roxarsone (4-hydroxy-3-nitro-phenylarsonic acid) and p-arsanilic acid (4-aminophenylarsonic acid) are feed additives widely used in the broiler and swine industry. This study evaluated the inhibitory effect of roxarsone, p-arsanilic, and other phenylarsonic compounds on the activity of acetate- and H(2)-utilizing methanogenic microorganisms. Roxarsone, p-arsanilic, and 4-hydroxy-3-aminophenylarsonic acid (HAPA) inhibited acetoclastic and hydrogenotrophic methanogens when supplemented at concentrations of 1mM, and their inhibitory effect increased sharply with incubation time.

Biologically mediated mobilization of arsenic from granular ferric hydroxide in anaerobic columns fed landfill leachate.

To gain insight on the fate of arsenic (As) from drinking water treatment residuals in landfills, the mobilization of arsenate adsorbed onto granular ferric hydroxide (GFH) was studied in continuous anaerobic columns fed with a synthetic landfill leachate. The release of As was compared in biologically active and abiotic columns. More than 150 days of incubation were required before noteworthy As release occurred.

Anaerobic biotransformation of roxarsone and related N-substituted phenylarsonic acids.

Large quantities of arsenic are introduced into the environment through land application of poultry litter containing the organoarsenical feed additive roxarsone (3-nitro-4-hydroxyphenylarsonic acid). The objective of this study was to evaluate the bioconversion of roxarsone and related N-substituted phenylarsonic acid derivatives under anaerobic conditions. The results demonstrate that roxarsone is rapidly transformed in the absence of oxygen to the corresponding aromatic amine, 4-hydroxy-3-aminophenylarsonic acid (HAPA).

Anaerobic microbial mobilization and biotransformation of arsenate adsorbed onto activated alumina.

Due to the enactment of a stricter drinking water standard for arsenic in the United States, larger quantities of arsenic will be treated resulting in larger volumes of treatment residuals. The current United States Environmental Protection Agency recommendation is to dispose spent adsorbent residuals from arsenic treatment into non-hazardous municipal solid waste (MSW) landfills. The potential of microorganisms to alter the speciation affecting the mobility of arsenic in the disposal environment is therefore a concern.

Methanogenic inhibition by arsenic compounds.

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

Facile reduction of arsenate in methanogenic sludge.

Due to the recent enactment of a stricter drinking water standard for arsenate, large quantities of arsenate-laden drinking water residuals will be disposed in municipal landfills. The objective of this study was to determine the role of methanogenic consortia on the conversion of arsenate. Methanogenic conditions commonly occur in mature municipal solid waste landfills.