The formation of chloroform (CHCl₃), carbontetrachloride (CCl₄), trichloroethylene (CHClCCl₂) and tetrachloroethylene (CCl₂CCl₂) after aqueous chlorination of aromatic hydrocarbons such as p-quinone (PQ), hydroquinone (HQ), catecoal (CA), p-hydroxy benzoic acid (PHBA), salicylic acid (SA) and benzoic acid (BA) was investigated.
The following results were obtained.
1) It is recognized that 6 compounds are CHCl₃, CCl₄, CHClCCl₂, CCl₂CCl₂ precursors.
2) CHCl₃ formation potential was increased by high pH value, but formation potentials of CCl₄, CHClCCl₂, CCl₂CCl₂ were increased by low pH value during aqueous chlorination.
3) Aromatic hydrocarbons which have substituent group in the paraposition produced volatile chlorinated organic compounds more than those in the ortho-position.
4) The effect of the ozonation of compounds was obserbed that the formation potentials of volatile chlorinated organic compounds were classifyed increasing group and decreasing group.

View full abstract

The successive extraction method with 0.1N HCl and 0.5N NH₄OH for the analysis of organic phosphorus in soils was applied to determine the phosphorus in activated sludges from 24 sewage treatment plants in Chiba Prefecture. The repeatability of this method was satisfactory and the sum of the phosphorus in HCl and NH₄OH extracts from the sludge was in agreement with the total phosphorus in the sludge which was measured after the digestion with H₂SO₄-HNO₃.
The phosphorus content was higher in inorganic fraction in HCl extract and organic fraction in NH₄OH extract than the other fractions. The inorganic phosphorus in HCl extract was considered the phosphorus which was accumulated by “luxury uptake” in the activated sludge and this phosphorus fraction was closely related to polyphosphates and metals such as Ca or Fe.
From the balances of phosphorus and sludge in an activated sludge process, the decrease of phosphorus concentration in the process was shown as follows : ΔP=aC' ΔBOD/ (1+bSRT) where C' was the phosphorus concentration in the microorganisms of the activated sludge. The amount of excess sludge per unit influent flowrate was found to be a factor controlling the phosphorus removal in an activated sludge process.

View full abstract

Laboratory tests of anaerobic-anoxic-oxic process by three kinds of apparatus consisting of a 30-litre capacity sequencing batch reactor and a nitrified liquor storage tank have been carried out to select the suitable fluidizing media for surface fixation of micro-organisms and to investigate the effects on higher biomass (VSS) accumulations in reactors.
Two kinds of glass beads which had 0.1mm and 0.05mm in diameter were selected as the media in reactors and another one which was operating as suspended growth was controlled.
Total operating time in a cycle was for 240 min. and volumatic ratio of nitrified recycling liquor to influent (R) were applied at the ranges of 0.5 to 3. The results were summarized as follows ;
(1) TOC, T-N and T-P removals were given as more than 90%, 65% and 83% respectively, when the tests were carried out at 1.7 or below of R and 5.6 g·l^-1 or higher of VSS concentrations in reactors.
(2) When reactors were operated under condition of 2.0 or more of R and 5.4 g·l^-1 or less of VSS concentrations, T-P removal were remained 50% or less.
(3) Settling characteristics of biomass in reactors were improved fairly by growth of fixed microorganisms.

View full abstract