CS251513B1 - A method of multistage biological activation purification of wastewater in pulp and paper production - Google Patents

Abstract

The method of multi-stage wastewater treatment consists in that the wastewater is adjusted to pH 7.5 to 8.5, preferably to pH 8, before the first stage, and to pH 5.5 to 6.5, preferably to pH 6, in the next stage, with the addition of biogenic elements of nitrogen and phosphorus. The solution can be used for wastewater treatment in the production of pulp and paper.

Description

251513

The present invention provides a method for the biological purification of wastewater from pulp and paper pulp production. Currently, single-stage and multi-stage biological activation procedures are used to purify wastewater from pulp and paper production. Knowing the undisputed advantages, these processes and the disadvantage of consuming electrical energy are necessary for arresting and high costs associated with the dispensing of nitrogen and phosphate salts, which atoll biogenic elements usually need to be dosed in a BSKs: N: P ratio == 100: 4: 0.8. Another disadvantage is the high costs involved in disposing of excess activated (sludge which, in this type of water, produces up to 0.5 kg per kg of degraded BSKs). KR Dietrich: Die Abwassertechnik, Alfred Húthing Verlag, Zleidelberg 1973.)

These procedures work by adding the abovementioned amount of biogenic N aP elements to the water lot before entering the activation and adjusting the pH to 7 to 7.5 (Klandúch, Balhar: Report on Business Travel to USSR 1977, VÚPC, Bratislava.) Addition of recirculated active potassium to water undergoes one- or multi-stage activation.

According to the present invention, the multistage activation purification of waste water by the production of ibunicum and paper is characterized in that the waste water is treated before the first stage to an alkali pH of 7.5 to 8.5, preferably to piH 8 without the addition of nitrogen and phosphorus compounds and before the next step sapH, the pH changes to an acidic pH of 5.5 to 6.5, preferably to 6, with the addition of nitrogen and phosphorus compounds. Of the nitrogen compounds, ammonia or urea and phosphorous or phosphoric acid are most commonly used.

The present invention is based on the findings of ourselves that cellulosic paper waters contain a group of substances, the first of which decomposes more rapidly at pH 8 and decomposition does not require biogenic elements and the other at pH 6a in the presence of biogenic nitrogen and phosphorus elements. Example 1

Alkaline effluent from the production of sulphate pulp with a concentration of 300 mg / l BSKs is adjusted by adding H 2 SO 4 to pH 7.5 and the addition of biogenic elements is added to the first stage of the multi-stage activation biological purifier continuously. activated sludge at 3 g / l. The mixture is aerated continuously by means of an aerator.

The water from the first stage continuously passes through the sedimentation tank, where the sludge-purified water is separated, is neutralized by the addition of H2SO4 continuously to pH 5.5 and enters the second stage of activation. Here, a biogenic nitrogen of 6 mg / l of treated water is added in the form of ammonia and phosphorus of 1.2 mg / l of treated water as phosphoric acid. In the second activation step, the water is treated with a reversible activated sludge and air as described in the first step. Water from the second activation reservoir enters the second stage of sedimentation. The settled purified water has a BSKs of 15 mg / L, the amount of excess activated sludge is 50 mg per 1.1 purified water. The efficiency is 95%. Example 2

One proceeds as in (Example 1, with the difference that acid wastewater from sulphite pulp production is used with a concentration of 350 mg BODs / l and this is adjusted to pH 8.5 by the addition of lime milk, with the difference that before by the second step, adjusting the pH to 5.5 is achieved by mixing with the acid waste water from the sulfite pulp.

The purified water has a BOD of 14 mg / l, the amount of excess activated sludge is 60 milligrams per liter of purified water. The efficiency is 96%. Example 3

It documents the current status. The procedure of satak, alcohol in Example 1 is followed except that the pH is adjusted to 7, and nitrogen is added in an amount of 12 mg / l, phosphorus at 2.4 mg / l before the first activation step. Further addition of biogenic elements and pH change before the second stage is no longer performed.

Purified BOD water of 29 mg / l, the amount of activated activated sludge is 125 mg / l of purified water. The efficiency is 90.3%.

By modifying the two-stage or multi-stage purification according to the present invention, a substantial reduction in the amount of excess activated sludge is achieved in half compared to the Idoteraz process used, thereby saving the disposal costs. Furthermore, a reduction in the consumption of nitrogen and phosphorus by 50% to 30% compared to the amount used up to now is achieved, as well as reducing operating costs, as well as increasing the efficiency of the biological treatment of wastewater.

Claims (1)

251513 SUBJECT A method of multi-stage biological activation purification of pulp and paper wastewater, characterized in that the waste water before (the first step of the invention is adjusted to a pH of 7.5 to 8.5, with a yield of 8 and beyond) step to a pH of 5.5 to 6.5, preferably to pH 6, with the addition of bio-elements of nitrogen and phosphorus.