RU1798335C - Method of sewage sediments disinfection - Google Patents

Abstract

Use: to prevent environmental pollution. SUMMARY OF THE INVENTION: Lime is added to the treated precipitate until an alkaline medium is created, then the precipitate is treated with an oxidizing agent - magnesium hypochlorite pulp followed by the introduction of acidic coagulant to create a neutral medium. 1 tab.

Description

The invention relates to the treatment of sewage sludge, in particular sewage sludge, and is directed to environmental protection.

The aim of the invention is to increase the degree of disinfection.

This goal is achieved in that in the method of disinfecting sewage sludge, including coagulant treatment, lime and mechanical dewatering, after the introduction of lime to create an alkaline medium, the sludge is treated with an oxidizing agent - magnesium hypochlorite pulp followed by the introduction of acidic coagulant until neutral Wednesday.

When hypochlorite pulp is introduced into a raw precipitate pre-treated with alkali, which is a colloidal system, a complex process occurs: on the one hand, the colloidal bonds of the precipitate are destroyed by the electrolyte contained in the hypochlorite pulp in quantities insufficient to coagulate the precipitate, On the other hand, at the same time

the particles released from colloidal bonds are oxidized by decomposition products of calcium hypochlorite. Thus, the introduction of hypochlorite pulp into the precipitate in an alkaline medium allows the oxidation of microorganisms under conditions when the colloidal bonds of the system are already destroyed and the formation of flakes has not yet begun. This allows a deep disinfection of not only the filtrate, but also the densified part of the sediment.

With the introduction of chloride coagulant, not only flocculation occurs, but also the disinfection of the precipitate. Moreover, the effect of pre-disinfection is higher than that which can be obtained only due to chlorine introduced with the coagulant. The mechanism for increasing the effect of pre-disinfection has not been clarified. The filtrate obtained after such treatment of the precipitate contains active chlorine in concentrations not exceeding the maximum permissible concentration for fishery reservoirs.

The method is carried out as follows.

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with

Lime milk is added to the crude precipitate to transfer the pH of the suspension from neutral or slightly acidic to a highly alkaline region, in which some heavy metals / precipitates precipitate (pH 9-11). Then, hypochlorite pulp is introduced into the resulting suspension with stirring, and the sediment disinfection process takes place within 30-40 minutes. After that, acidic coagulant is introduced until the suspension reaches a pH of 6-7. The mixture is stirred and incubated for 30-40 minutes and then subjected to vacuum filtration. The filtrate is discharged into a reservoir, and the compacted sediment is disposed of.

Examples of the method.

The method was implemented on the raw sludge of Zaporizhzhya municipal wastewater, having the following indicators: total microbial number 2 -10s; coli index 2.3 108; CI not detected; MP 0.016 May. dale % (on a dry matter basis); humidity 98%.

The precipitate was treated with the following reagents.

Koagul NT - 10% solution of degassed ZTMK sublimates. The composition of the sublimates, May. dale %: TI 7.17; SG42.7; C 23.6; Fe 6.15; AI 4.61; Si 3.51; Ca 0.74; Md 0.95; Mp 2.38; Cr 2.14; Јр.э. No. 0.201.

Lime - 10% solution (in terms of CaO). ,

Typochlorite pulp (waste magnesium production) with content. 110 g / l, Ca (OH) 2 30 g / l.

Example 1 (prototype). A 1 L crude sludge is placed in a 2 L beaker; 12 ml of an aqueous coagulant solution containing 1.2 L of degassed sublimates and 0.072 g of dioxide are introduced with stirring.

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calcium. 24 ml of lime solution are added, stirred for 30-40 minutes and vacuum filtered.

Example 2 (by the proposed method). A 1 liter of crude sludge is placed in a 2-liter beaker, 4 ml of a solution of lime are added and mixed, 30 ml of a solution of hypochlorite pulp are added with stirring and the mixture is kept for 30-40 minutes. After that, 12 ml of a solution of acidic coagulant is introduced to a pH of 6-7, again incubated for 30-40 minutes and subjected to vacuum filtration.

The results of the experiments are shown in the table.

The table shows that when the sludge is treated with municipal waste according to the claimed method, not only the filtrate is disinfected, but also the compacted part of the sludge. Compared with the prototype, the total microbial number (TBC) in the sediment is reduced by 300 times; coli index (CI) - 20 thousand times. In addition to improving bacteriological parameters, the manganese content in the filtrate is reduced to values below LDK for discharge of water into reservoirs of fishery value.

Claims (1)

SUMMARY OF THE INVENTION A method for disinfecting sewage sludge. comprising treating with coagulant, lime and mechanical dehydration, characterized in that, in order to increase the degree of disinfection, after the introduction of lime to create an alkaline medium, the precipitate is treated with an oxidizing agent - magnesium hypochlorite pulp followed by the introduction of acidic coagulant to create a neutral medium.