A mathematical model simulating the nitrification process in a tublar wastewater treatment contactor was presented. According to the model, the operation of nitrification are quantitatively analyzed.
When the reaction rate is not affected by the liquid phase mass transfer resistance in honeycomb tube, a specific relation between the effluent BOD and NH₄-N concentrations. Which is similar to that obtained for the activated sludge and rotating biological contactor process, can be obtained. When the reaction rate is controlled by the liquid phase mass transfer resistance, on the other hand, little higher effluent NH₄-N concentration than that in the former case at low BOD concentration is obtained.
Methods to predict the NH₄-N removal under various operating conditions of the contactor for two cases : the oxygen-supply-controlling and the oxygen-transfer-controlling, were also presented. The results of the illustrative calculations were compared with the observed data and discussed.

View full abstract

An anoxic-aerobic high concentration activated sludge process imbued with a highly effective nitrification and denitrification performance was investigated. The novel and unique feature of this process is unlike other methods of nitrogen removal process, the wastewater influent is introduced into an anoxic tank, wherefrom, the treated effluent is likewise withdrawn.
A kinetic analysis was performed on the data obtained from the bench-scale experiments conducted on synthetic domestic wastewater, synthetic night soil and synthetic PVA wastewater, and summarily, our deductions are as follows;
1) This process could remove not only TCO and Total-N but also recalcitrant polyvinyl alcohol (PV A) substance.
2) We obtained various kinetic formulae for this nitrogen removal process and established the determiation methods for the kinetic constants.
3) The reaction in an aerobic tank follows a 1st order kinetics while the reaction in an anoxic tank follows a zero order kinetics.
4) We established the calculation formulae for an appropriate aerobic tank volume, appropriate anoxic tank volume and appropriate sludge recycle flow rate which are important variables for the design and operation of this process.

View full abstract

Water samples taken from the center of Lake Kasumigaura (Nishiura and Kitaura) which was an eutrophic lake in Japan were measured for the dissolved organic metters during May 1974 to May 1975. And the water samples of Lake Kitaura were determined for dissolved organic carbon (DOG), dissolved carbohydrates (DCHO) and dissolved amino acids (DAA). Relationship between chlorophyll-a as index of phytoplankton and, DOC, DCHO and DAA was discussed. The correlation between chlorophyll-a and DOC and DCHO was observed in Lake Kitaura water. But no relationship between chlorophyll-a and DOG was observed in Lake Nishiura water. Throughout the experimental period, only about 18% of DOC could be attributed to DCHO and DAA carbon and about 22% of DON could be attributed to DAA nitrogen but larger fraction remained to be identified.

View full abstract

The treatment of waste solution containing cyanide methemoglobin and cyanide ion, which result from the assay of hemoglobin content in the blood, was investigated in terms of the separation of two cyanide components. The cyanide methemoglobin was separated by means of the flocculation with polymer flocculant. Potassium poly (vinyl alcohol) sulfate (KPVS) flocculates quantitatively cyanide methemoglobin, whereas poly (acrylamide), poly (acrylic acid) and poly (diallyldimethylammonium chloride) are not effective for the flocculation of cyanide methemoglobin. From the results of colloid titrations for human carboxyhemoglobin and for cyanide methemoglobin in the waste solution, the mechanism of the fllocculation was interpreted by the formation of polyion complex between hemoglobin and KPVS, based on the stoichiometric saltlinkage formation of amino, imidazole, and guanidyl groups in the hemoglobin with sulfate groups in KPVS. On the other hand, the cyanide ion in the waste solution of which the cyanide methemoglobin was flocculated and/or separated, can be removed in the usual ways such as the aeration and the alkaline chlorination On the bases of the results mentioned above, two possible processes for the treatment of the waste solution are presented.

View full abstract

Experimental study on biological denitrification of a municipal sewage has been performed without chemicals, applying a pilot plant of a modified activated sludge process. In this plant, a denitrification tank whose volume is about 1.69 m³ and retention time is about 34 minutes is installed at the head part of the aeration tank. The retention time of the aerated part of the aeration tank is kept to around 2.44 hrs. The sludge return eturn ratio is ranged from 0.5 to 2.0.
The removal of organic materials measured by CODcr is successful and the removal efficiency is in the range of 78.6-89.5%. The denitrification reaction takes place in the denitrification tank and the final sedimentation tank. The total removal efficiency of nitrogenous compounds increases with the increment of the sludge return ratio. The oxidized nitrogen removal efficiency in the denitrification tank is in the range of 66.8-84.9%. The alkalinity necessary for the nitrification of ammonium nitrogen is successfuly supplied from that of influent and the product of denitrification reaction without the addition of special alkalinity.

View full abstract

The amount of phosphate removal from the water by using Zenigamezawa volcanic soils was examined on the condition of phosphate in the river water which differed from water qualities. These removal values from the water of River Shinkawa increased with lapse of incubated time from 1 to 28 days.
Compared with the effect of water quality of Rivers Toyohira, Hassabu, and Shinkawa on such removal values, there were no clear differece among kinds of rivers. Conversely, the values of EC, Acidity, Alkalinity and COD in the Shinkawa were remarkably higher than that on the Toyohira and the Hassabu. These results suggest that the amount of phosphate removal are influenced by forms of dissolved phosphate rather than the water quality.

View full abstract