CS258693B1 - A way to increase the efficiency of biological purification of waste wastes serving bound forms of formaldehyde - Google Patents

Abstract

The essence of the solution is that biological cleaning by activation takes place at pH values of 5.5 to 6.5, preferably 6. Adjustment of the pH of the activation medium is achieved by adjusting the pH of the waste waters and their controlled dosing or directly by adjusting the pH of the activation medium. Waste acids or preferably acidic waste waters are added. There is a significant increase in the efficiency of the cleaning process as a result of the several-fold speed of decomposition of the bound formaldehyde.

Description

The present invention relates to a method for increasing the efficiency of biological treatment of waste leaders comprising bound forms of formaldehyde.

In cleaning waste leaders from the chemical industry, the biological stage implemented as activation is critical to cleaning. Activation purification is carried out in practice at pH 7.0-8.5. These pH values are considered optimal.

If wastewater contains bound for- formaldehyde, especially hexamethylenetetraamine, does not significantly decompose these compounds when purified by activation in the pH 7.0-8.5 range and hence their sufficient removal in the purification process.

It has now been found that the efficacy of the biological purification of waste leaders comprising bound forms of foaldehyde, according to the invention.

The essence of the invention is that biological purification by activation takes place at pH values of 5.5 to 6.5. It is preferred that the pH value be 6. The pH adjustment of the activation environment to the desired value can be achieved by adjusting the pH of the effluent lines and their regression dosing, or by adjusting the pH of the activation environment by adding waste acids. It is advantageous if pH adjustment is achieved by adding acidic waste leaders.

Table pH = 6 Time (d) Total formaldehyde (mg. I’1) Speed removal (mg.g-1.hr 0 228 3 114 5.16

Claims (1)

SUBJECT A method for increasing the efficiency of biological treatment of wastewater containing wet forms of formaldehyde, characterized in that biological treatment by activation is carried out at pH values of 5.5 to 6.5, preferably 6, whereby this pH adjustment to the specified value If biological treatment by activation is carried out at pH values of 5.5 to 6.5, there is no decrease in the activity of microorganisms of the activated sludge and the treatment process can proceed at an undiminished speed. At these values, however, the decomposition of bound forms of formaldehyde, in particular hexamethylene tetramine, into formaldehyde and ammonia simultaneously occurs. The decomposition reaction proceeds at a relatively low speed, but the residence time of the wastewater in the activation tanks is relatively long enough for it to take place. The microorganisms of the activated sludge immediately metabolize the resulting formaldehyde, which, from the point of view of the kinetics of the process, shifts the entire reaction in the direction of decomposition of hexamethylene tetramine. This increases the cleaning efficiency in the bound formaldehyde indicator. The subject matter of the invention is illustrated, but not limited, by the following example. Example 1 The rate of hexamethylenetetramine depletion in wastewater was monitored in a kinetic text with adapted activated sludge at pH values of 6.0 — 7.5. The results are in the attached table. pH = 7.5 Total Speed formald. delete mg. T' ¹ mg.g-^h 310 272 1.04 The above-mentioned is achieved by controlled dosing and pH adjustment of the wastewater flowing into the activation environment and/or by directly adding acidic wastewater to the activation environment.