Adsorption and biodegradation of linear alkylbenzene sulfonate (LAS) on activated sludge has been studied using Abbott's methylene blue method and high-performance liquid chromatography (HPLC), and the following results are obtained;
(1) No accumulation of LAS in activated sludge was observed.
(2) The disappearance of LAS homologues/isomers was occured in the order of C₁₃ to C₁₀ homologues and 2-phenyl to inner phenyl isomers in both effluent and sludge.
(3) As biodegradation intermediates of LAS, several peaks were observed on the HPLC chromatograms, but most of these peaks disappeared within 24 hours of incubation. Furthermore, one of these peaks was identified as 3-(4-sulfophenyl)butyrate(SφB).
From these results, it is confirmed that LAS is adsorbed onto activated sludge and then immediately biodegraded.

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Ammonium nitrogen (NH₄⁺-N) in sediments exists as two types; (1) Dissolved in interstitial water, (2) Adsorbed onto sediment particles.
In this paper, mechanism of NH₄⁺ adsorption and it's effect on the release process were studied.
The conclusions were as follows;
(1) NH₄⁺, together with other cations, is adsorbed onto the negative charge of sediment particles (Ion exchange adsorption).
(2) Adsorption equilibrium is expressed by the Freundlich equation.
(3) Adsorption equilibrium is changed mainly by two factors; (a) Cation Exchange Capacity (CEC) of sediment, (b) Coexisting cations in sediments (Ca²⁺, Mg²⁺, Na⁺, K⁺ etc.), especially relative concentration level of them and NH₄-N in interstitial water.
(4) Mathematical model of release process was presented. As a result of calculation, it was found that correct evaluation of adsorption equilibrium was necessary to analyze or predict the release flux of NH₄⁺-N from sediments.

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Chloroform formation by chlorination of humic acid in the presence of different metals were investigated.
The following results were obtained.
(1) Fe²⁺, Sn⁴⁺, Cr₂O₇^2-, Ni²⁺, SeO₄^2- and Pb²⁺ had no effect on chloroform formation by chlorination of humic acid.
(2) Mn²⁺, SeO₃^2- and Co²⁺ decreased chloroform formation, because these metals consumed an available chlorine demanded in chloroform formation of humic acid. However, MnO₄^- decreased chloroform formation because permanganate oxidized humic acid.
(3) Cu²⁺, Al³⁺, Fe³⁺ and Zn²⁺ accelerated chloroform formation because of catalyst-like function, the efficiency being in the decreasing order Cu²⁺> Al³⁺> Fe³⁺> Zn²⁺.

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By using filtered sea water and oyster shell taken from the northern area of Hiroshima Bay, degradation of LAS by bacteria was investigated during 53 days. In order to study the fluctuation of LAS and its biodegradation intermediates, HPLC (high pressure liquid chromatograph) was used in addition to measurement of TOC and MBAS (methylene blue active substances).
Furthermore, effects of LAS and its proposed metabolites on the growth of Skeletonema costatum and Heterosigma sp. were investigated. It was observed that the growth of Skeletonema costatum was accelerated or depressed in the difference of LAS concentration, and that of Heterosigma sp. was depressed.

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