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In this study, anaerobic biodegradability of 47 kinds of aliphatic compounds was tested and assessed in integrate. These aliphatic compounds were classified into readily, partially and poorly biodegradable compounds after their integrated assessment indices (IAI) were calculated. Some laws of anaerobic biodegradation of aliphatic compounds were drawn. Stepwise regression and back propagation artificial neural network (BP-ANN) methods were applied to establish quantitative structure biodegradability relationship (QSBR) based on the assessment results. In QSBR models, six molecular structure descriptors were included. After analyzing the sensitivity of variables in QSBR models, it was found that the key molecular structure descriptors affecting anaerobic biodegradability of aliphatic compounds were total energy (TolE) and molecular diameter (D), which were in direct proportion to the anaerobic biodegradability of aliphatic compounds. [Copyright &y& Elsevier]

With various concentrations of CaCl2 and MgCl2 aqueous solution below 1.0 mol/l, Raman spectra of water in the OH stretch region of 2500–4000 cm−1 and 17O NMR chemical shift of water are measured and the Raman spectra are deconvoluted. Both Raman spectra and 17O NMR of water show that the effect of Ca2+ on water structure is stronger than that of Mg2+. CaCl2 and MgCl2 destroy four hydrogen bonded water structure, but promote median water cluster size. [Copyright &y& Elsevier]

Discusses factors that can affect the biodegradability of organic substances in water. Oxygen consumption; End products; Activities of microorganisms.