JPS6161694A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To increase the efficiency of the titled process by regulating raw water to the pH that the treatment efficiency becomes maximum before introducing the raw water into a treatment apparatus and thereafter introducing it into a biological treatment apparatus. CONSTITUTION:The pH value that the treatment efficiency becomes maximum is obtained in every waste water by means of preliminary experiment and the pH of raw water is regulated to the obtained pH and thereafter it is treated. In case of providing two or more stages of treatment vessels, COD contained in treated water of each stage on and after the second stage is adopted as the indication and raw water is passed so that the pH in which COD is made minimum becomes optimum pH. In regulating pH of raw water, NaOH or NH4OH is used as alkali and inorganic acid is used as acid.

Description

[Detailed description of the invention]

This invention provides a method for biological wastewater treatment in which raw water is adjusted to an optimum pH value that maximizes treatment efficiency before introduction into a treatment device, and then introduced into the biological treatment device, and in the second and subsequent stages, the raw water is introduced into the biological treatment device. The present invention relates to a method of treating raw water by controlling the pH value to a value that minimizes the COD of treated water. Conventionally, there has been a fixed concept that the maximum aph in biological wastewater treatment is neutral, and therefore, regardless of the type of wastewater, it has generally been neutralized to make it neutral. Furthermore, although it has been empirically known that pH increases during the purification process of wastewater, it has not been recognized as a factor that reduces purification efficiency, and therefore no control has been carried out. Furthermore, although it has already been done to divide the treatment tank into two or more stages and adjust the biota in each stage to a form suitable for the wastewater purification process, it is difficult to control the pH of each stage to the optimum pH. No attempt was made to improve efficiency. The purpose of the present invention is to adjust the pH of raw water so as to maximize the biological treatment efficiency, which varies depending on the type of wastewater (substrate contained). is determined, and the pH of the raw water is adjusted to this value. In addition, when two or more stages of treated treetops are installed, the pH is adjusted to minimize the COD using the COD in the treated water of each stage from the second stage as an index.
The solution is passed through the solution until the pH reaches 1. Log pH! l! 11! ' is Na0 as an alkali
) 1, NH, OH, and as the acid, carbonic acid and sulfuric acid are preferable in order to reduce the inhibition of the functions of the living organisms, and organic acids are not suitable as they increase the pollution load. An experimental example for determining the optimum pH in the present invention will be described below. Experimental Example 1 The relationship between the pH of raw wood and treated water P)I was determined using a fluidized bed catalytic oxidation device using caramel and drop confectionery wastewater as raw water. The results were as shown in the figure. Raw water: BoD 7000 181 sentences, Goo
3100 servings/1. pH=3.0 Izj e Ilt catalytic oxidation treatment conditions. Fluidized bed volume 5.34 sentences, carrier filling rate 30% Nutrition JI
N: 0.05/BOD Heavy duty section P: 0
．． 01/BOD heavy ji) part +/, cki JIi2. θ/min (105rn'/BO
D-kg) Empty speed 11' 33 +1iL/am'
・Minute MLSS 11150~2050 B/fL
Raw water residence time 23.5h, (BOD load B, fi3k
g/fluidized bed g/day) The pH of the raw wood was adjusted with a NaOH aqueous solution. The printed honorifics are the COD value of the treated water [mg/gL+, (
) is BoD Detective

[1g1 sentence]. When the raw water pH is 6 or more, the pH of the treated water decreases, and when the pH is 6 or less, it increases. When pH=4.8, the pH of the treated water was 7 to 8, the rate of increase in pH was the highest, and the COD of the treated water was also the lowest. In addition, if neutralization treatment is not performed, the treated water quality will be COD.
It gradually improved from 9Hmg/view to 2825@g/text. In addition, in the case of raw water pH -11.3, the pH of the treated water decreased to around 7, but the liquid viscosity in the fluidized bed increased and finally became jelly-like. Based on the above experimental results, it is pointed out that the raw water before entering the treatment Fll is
The H value can be determined to be around 5. When the pH of the raw water was adjusted to 5 and the solution was passed through the solution, the desired results were obtained. Experimental Example 2 The treated water obtained from the fluidized bed catalytic oxidation device of Example 1 was subjected to PR adjustment as raw water, and it was subjected to a biological treatment test using a natural road fixed bed catalytic drunkenning device.The results were as follows. Ta. Raw water 2, BOD745 fat gel, COD573mg/4
1゜Processing conditions Gravel bed volume 810.51. i1! Filling rate 55% air 1
k 12.5 mfi/sin (80m'/BOD
kg), residence time 30 h The po of the treated water in the second stage increased from before the treatment and reached pH 81.
Since it converges after iII, the search for the indicated pH is a focal point. Therefore, COD that can measure COD in treated water in a short time
It is preferable to use a meter as a detector to detect the pH, and set the pH at which the COD value is suppressed as the indicated pH. In the great invention, even in the case of one stage and two or more stages, feed forward' is based on the above optimal P)I by computer control.
By controlling aj, the effect can be further improved. Note that the present invention can also be applied to the production of useful compounds by culture methods.

[Brief explanation of the drawing]

The figure is a graph showing the relationship between the pH of raw water and the pH of treated water and the change in COD in one experimental example.

Claims (2)

[Claims] (1) In biological wastewater treatment, within the range where the pH of the treated water is higher than the pH of the raw water, the pH of the raw water where the pH increase rate is the highest is set as the optimal pH and adjusted before introducing it into the treatment equipment. A wastewater treatment method characterized by passing the liquid through the wastewater. (2) In biological wastewater treatment performed by dividing the treatment tank into multiple stages, in the first stage, the pH of the raw water is adjusted to the maximum pH increase rate within the range where the pH of the treated water is higher than the pH of the raw water. A wastewater treatment method characterized by adjusting the pH to an optimum pH before introducing the wastewater into a treatment device and passing the solution through the process, and adjusting the pH to a pH that minimizes the COD value of the treated water in the second and subsequent stages. Method.