Ammonium nitrogen, biodegradability

Biodegradation. Under aerobic conditions, biodegradation results in the mineralization of an organic compound to carbon dioxide and water and—if the compound contains nitrogen, sulfur, phosphorus, or chlorine—with the release of ammonium (or nitrite), sulfate, phosphate, or chloride. These inorganic products may then enter well-established geochemical cycles. Under anaerobic conditions, methane may be formed in addition to carbon dioxide, and sulfate may be reduced to sulhde. 

Cationic surfactants produce a positively charged surfactant ion in solution and are mainly quaternary nitrogen compounds such as amines and derivatives and quaternary ammonium salts. Owing to their poor cleaning properties, they are little used as detergents rather their use is a result of their bacteriocidal qualities. Relatively little is known about the mechanisms of biodegradation of these compounds. 

There was a large decrease in levels of TOC and DOC over the 14 day incubation period. Dissolved material accounted for 74% of the TOC present initially and both fractions were removed by over 70% by day 14 (Table 10.4). The diluted effluent initially contained 4mg/l phenol, which had been biodegraded by 60% after 14 days of incubation. As seen previously with refinery process effluent A, ammonium levels fell and then rose (Table 10.4) but there was negligible increase in oxidised nitrogen, indicating that little nitrification was occurring during incubation. 

The positive ionic charge, based on the nitrogen atom of a quaternary ammonium group, provides the antimicrobial properties. Quaternary ammonium compounds have a number of advantages, i.e. they are readily biodegradable, non-toxic, non-corrosive (at in-use concentration) and have no odour. 

Oxidation-reduction processes are very important in the nitrogen cycle. The initial product of the biodegradation of nitrogen-containing biomass (protein) and the form normally applied to farm lands as fertilizer is ammonium ion, NH4. To be assimilated as a nutrient by algae or in field crops, it normally requires microbial oxidation to NOj ... 

Amine alkoxylates are not the only nitrogen derivatives to find utility in agrochemical applications quaternary ammonium salts [79], amine oxides [80], alkylamidoamines [81] and betaines [82] are also reported to have similar bioefficacy-enhancing properties to fatty amine alkoxylates. There has also been development of adjuvants with improved biodegradability and certain fatty esteramine and amidoamine deriviatives, for example, have been developed that exhibit enhanced biodegradability [81]. 

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