Effects of biodegradation of LAS on activated carbon were investigated to obtain some basic information on the combination of wastewater treatment process.
LAS (p-n-dodecylbenzenesulfonate) was subjected to biodegradation by shaking culture method using unacclimated activated sludge. Filtrate of these culture were put to adsorption equilibrium test on activated carbon. All tests were conducted at 25°C and the initial concentration of LAS was 30 mg/l. LAS was detected mainly as methylene blue active substance and total organic carbon.
LAS was biodegraded more easily when coexisting with degradable wastewater than when given as a sole carbon source. The adsorbability of LAS on activated carbon was lowered with the progress of biodegradation which decomposed the LAS molecule and produced some metabolites. The quantities of activated carbon necessary to remove LAS to a certain level increased in comparison with the case of considering concentration change of LAS only.
It was necessary to take the change of the chemical nature of LAS into account together with the concentration reduction during biodegradation to get an effective combination of LAS removal process.

View full abstract

The distribution of MBAS in a small and shallow pond was investigated.
The conclusions are summarized as follows.
1) The ratio of DOC to POC is 5.5 to 1. 3, which is affected strongly by the amount of algae in water.
2) There is no MBAS in suspended solid and it is speculated that the accumulation of MBAS in the bottom muds is caused by the adsorption of MBAS on the bottom muds from water.
3) The rate of decomposition of MBAS not in the bottom muds but in water is strongly affected by the season.
4) The ratio of MBAS to organic matters in water and in the bottom muds is 3.9% and 0, 29% respectively.
5) The rate of decomposition of MBAS in the bottom muds is faster than that of T-P, T-N and organic matters.

View full abstract

Cation-exchange capacity (CEC), ignition loss, clay fraction and heavy metal content were measured in bottom sediments from the Nagara River, and the data were subjected to multiple regression analysis.
The average CEC of sediments in the middle and lower reach of the river were 3.23 and 10.5 meq/100 g respectively. Good correlations were found between CEC and ignition loss or clay fraction, and multiple correlation coefficients were more than 0.92 among them. From regression equations it was possible to estimate the CEC of ignition loss and clay fraction, and they were 0.41-1.0 meq/g and 0.36-0.49 meq/g respectively. Relative contribution to CEC was comparatively more dependent on clay fraction than ignition loss. A good relationship was observed between CEC and heavy metal content at every sampling station.

View full abstract

A water sample from Tama River was concentrated into one fourhundredth volume by rotary evaporator. A half of the concentrate was fractionated into five pools by gel chromatography on a column of Sephadex G-25. Another half of the concentrate was chlorinated with sodium hypochloride and fractionated into five pools by the same procedure. These pools were lyophilized. Neither of these pools showed mu tagenic activity at a maximal dose of 3 mg/plate when these pools were assayed by the Ames Salmonella test in the persence or absence of S-9 mixture.
Humic acids which are considered as a prominent component in some of natural water were prepared from a water sample from Kushiro River. This preparation did not show mutagenic activity while a commercial product of humic acids showed low but definite activity.

View full abstract

Some of the water soluble high polymers such as poly (oxyethylene), carboxy methyl cellulose and poly (vinyl alcohol) are biore-fractory and also insusceptible to ordinary activated carbon adsorption treatment because of slow adsorption rate. For removing these high polymers, degradation of molecular weight becomes advantageous as a pretreatment for succeeding biochemical or adsorption treatment. The present study focuses on elucidation of decomposition rate of poly (oxyethylene) in aqueous solution by ozone injection. In the course of reaction, gel chromatographic technique is used to obtain molecular weight distribution and from the measured distribution curve, number averaged molecular weight is calculated by assuming logarithmic normal distribution and by correcting the effect of axial dispersion in gel columns.
Decomposition rate is proportional to ozone concentration and to -1/3 power of polymer concentration. Activation energy of decomposition was 12.3 kcal/mole.

View full abstract

The main objective of this paper is to reveal the water quality evaluation techniques from the view points of Triharomethane formation of natural waters which are utilized for public water supply.
The major results are followings.
(1) The different fractionated components which are classified on the basis of molecular weight show different THM formation potentials.
(2) The THM formation potentials of the treated water by coagulation, activated carbon adsorption and ozonation processes are different because of different molecular weight distributions of their remained organic substances.
Therefore the classification of organic substances by their molecular weights and the measurement of THM formation potential of each classified component are important for the selection of treatment processes.

View full abstract

Heavy metals in sediment are oxidized under aerobic condition and then changed into other chemical forms in process of airdrying of river sediment. In order to investigate the behavior of heavy metals in the sediment during this process, heavy metals and sulfate ion were extracted from sediment with distilled water and dilute hydrochloric acid. Concentrations of heavy metals and sulfate ion in the extracted solution were determined by atomic absorption spectrometry and colorimetry, respectively. pH and oxidation-reduction (rodox) potential of the sediment were measured and sulfide content was determined by titrimetry.
In the airdrying process of the sediment, pH was decreased and rodox potential was increased. According as increasing of rodox potential, sulfide content of sediment was decreased and sulfate was increased. All of ferrous iron was oxidized to ferric before rodox potential reached to +50 mV (Eh_sce).
Cadmium, zinc and copper were changed from sulfide into sulfate in the airdrying process and it resulted in increasing of their solubilities in water. In the case of cadmium, water-soluble chemical form in the air-dried sediment was more than 17% of the total content. Therefore, on the disposal of dredged sediment containing a large amount of cadmium, cadmium could dissolved from dredged sediment into rain water and the pollution by cadmium is possibly expected.

View full abstract