RU2042645C1 - Method of sewage treatment from heavy metals - Google Patents

Abstract

FIELD: sewage treatment. SUBSTANCE: method involves the use of supernatant after microbial coal processing as a sorbent. Sorbent oxidized coal contains active carboxy-groups 4 mg-equiv./g (not less), capacity of cationic exchange is 103-148 mg-equiv./100 g and content of immobilized microorganisms is 5.5-10.4 billion/g. Use of sorbent at concentration 100-250 g/1 g metal ensures to decrease the residual concentration of heavy metal in sewage up to permissible concentrations. The source of microorganisms: a mixture of microbe cultures Acinetobacter coaleoacetficus, Pseudomonas denitrificans, P. louda at the weight ratio 1:1:1. In the immobilization process phosphate fertilizer is added firstly to coal (1 g per 50 g coal), and after stirring slaked lime is added up to pH 7. EFFECT: improved method of sewage treatment. 2 cl, 3 tbl

Description

 The invention relates to the treatment of wastewater from heavy metals using organic sorbents.

 As biological sorbents, microorganisms immobilized on a carrier are used.

 The disadvantage of these methods is the lack of ability of carriers to sufficiently adsorb heavy metals.

 From an economic point of view, the most promising sorbents obtained from industrial wastes and substandard materials.

 A known method of wastewater treatment from heavy metals using an organic sorbent obtained by chemical oxidation of coal. The introduction of this method has a better perspective at the enterprises of the coal industry, in which coal is a product of production. The availability of feedstock allows sorbents to be obtained in quantities sufficient to treat a large volume of wastewater at coal enterprises.

 The disadvantage of this method is the low efficiency of sorption at high initial concentrations of heavy metals in wastewater due to the low capacity of the sorbent.

 A known method of wastewater treatment from metals using yeast Laccharomyces carlsbergensis, immobilized on filter paper, which is a waste product.

 The method is characterized by the joint extraction of metals by the carrier and microorganisms while maintaining the efficiency of metal extraction during the treatment of highly concentrated wastewater. A feature of the combined biological sorbent is that the carrier is not a nutrient substrate for the growth of microorganisms. The expansion of the sorbent production volume causes additional costs associated with the use of a nutrient substrate for the growth of microbial biomass. Therefore, the disadvantage of this method is the difficulty of its implementation in enterprises with a large volume of wastewater due to the lack of sorbent and the costs of its acquisition or production.

 The invention improves the degree of wastewater treatment from heavy metals when using a coal sorbent by increasing the efficiency of sorption and the capacity of the sorbent.

 The essence of the invention lies in the fact that for the treatment of wastewater from heavy metals, a centrifugate of microbial coal processing is used as a sorbent. Sorption of heavy metals is carried out by coal particles and microorganisms immobilized on them. Coal processing into sorbent is carried out using the same microorganisms, and their immobilization is carried out simultaneously with processing. Brown raw and substandard oxidized coals, as well as oxidized coals, are used as raw materials for the production of sorbent. An increase in the efficiency of sorption and the capacity of the sorbent is achieved by improving the sorption properties of coals during their microbial processing and the participation of microorganisms in the sorption of metals.

 The method is as follows.

 A sorbent in the amount of 100-250 g per 1 g of metal dissolved in water is added to the sump with wastewater. Mixing the resulting suspension occurs when it is jointly supplied and with the help of air supplied to the sump from the compressor for 15-20 minutes. The settling time is determined by the transparency of the supernatant, which is compared with the standard on a photoelectric colorimeter. After settling, the purified supernatant is drained, and the remaining sorbent is regenerated or burned.

 Obtaining a sorbent is carried out as follows.

Oxidized brown coal of the Borodino deposit, having the following characteristics, A ^d 10.6, V ^dat 51.2, C ^dat = 58.8, H ^dat 4.2, N ^dat 1.1, S ^d 0.2, W ^r 32 , 5, crushed in a mill to a size of 0-300 microns and loaded into the reactor in an amount of 400-470 g (in terms of dry weight) per 1 liter of water. Phosphorite flour is added at the rate of 1 g per dry 50 g of coal. The contents of the reactor are stirred using a mechanical stirrer for an hour, then the slurry is adjusted to pH 7 with slaked lime. A mixture of microbial cultures Acinetobacter coa leoauticus, Pseudomonas denitrificaus, Pseudomonas Londa in a weight ratio of 1: 1: 1 is used as inoculum. An inoculum is added to the reactor at the rate of 1 g of inoculum per 1 kg of coal (in terms of dry weight). In subsequent cycles of sorbent production, the remainder of the coal pulp from the previous cycle in the amount of 1/5 of the working volume of the reactor is used as inoculum.

In the resulting product, the content of active carboxyl groups, the cation exchange capacity and the content of microorganisms are determined. The time needed to obtain a product in the reactor is 21-28 hours. The product was centrifuged and the precipitate was dried at 60 ° ^C to constant weight. The resulting sorbent is a black powder and is characterized by the following indicators: the content of active carboxyl groups is at least 3 mg / equiv / g, the cation exchange capacity is 103-148 mEq / 100 g, the content of microorganisms is 5.5-10.4 billion / g .

 EXAMPLE 1. 100 ml of a model solution containing various concentrations of copper, zinc, manganese and lead ions are poured into flasks and 1 g of sorbent is added. The contents of the flasks are stirred and left to stand for 24 hours. Then the sorbent is separated from the water by filtration and the residual concentrations of heavy metals are determined in the filtrate by atomic absorption method.

 The data presented in Table 1 show that the capacity of the sorbent upon absorption of heavy metals increases with an increase in the initial concentration of metals and reaches its highest value for copper 190.1 mg / g, zinc 183.2 mg / g, manganese 180.1 mg / g and lead 182.0 mg / g. The residual concentration of metals in solution at an initial concentration of 10 mg / l does not exceed the MPC. Lower residual concentrations to MPCs can be achieved by phased purification. In the known method, the sorbent capacity is 22.38 mg / g.

 PRI me R 2. 100 ml of model solutions containing 32 mg / l of ion-copper, zinc, manganese and lead are poured into flasks, and various amounts of sorbent 50, 100, 150, 200, 250, 313 are added. 5 g per 1 g of metal. The contents of the flasks are stirred and left to stand for 24 hours. Then the sorbent is separated from the water by filtration and the residual concentrations of heavy metals are determined in the filtrate.

 The effect of sorbent dosages on the efficiency of water purification from heavy metals is presented in Table 2.

 The data given in Table 2 show that in one-stage purification, 100-250 g of sorbent per 1 g of metal is required to reduce metal concentrations to MPC.

 At sorbent dosages less than 100 g per 1 g of metal, the residual concentrations of all metals exceed the MPC. The data given in Table 2 show that in order to achieve the maximum permissible concentration, the dosage of the sorbent for copper is 100 g / g, for zinc 150 g / g, for manganese 250 g / g, for lead 250 g / g. The lower limit of the dosage of the sorbent 100 mg / g is determined by the sorption of copper, and the upper limit of 250 g / g by the sorption of manganese and lead.

 When making the sorbent in an amount of 312.5 g per 1 g of copper, the known method provides water purification from 32 mg / g to 1.1 mg / l, and the proposed method from 32 mg / l to 0.023 mg / l, which is lower than the MPC equal to 0.1 mg / l (table 2). The advantage of the proposed method is also manifested in a more economical consumption of the sorbent, according to the known method, water purification to a copper level of 1.1 mg / l requires the introduction of 312.5 g of sorbent per 1 g of metal, and according to the proposed method, no more than 100 g / g. In addition, as a nutrient medium by a known method requires expensive and scarce products, and the proposed coal, available in sufficient quantity and at an affordable price.

 PRI me R 3. Technogenic wastewater of the Nazarovsky open pit is poured into the sump and 100 g per 1 g of metal is added to the sorbent. The contents of the sump are mixed with air supplied from the compressor for 15 minutes and settled. At certain intervals, the residual concentrations of metals in water are determined. The use of the sorbent is most effective in the treatment of wastewater from zinc and lead (Table 3). A significant decrease in zinc concentration from 0.012 mg / l to 0.0018 g / l is observed after 9 days of settling. By the 49th hour of sedimentation, zinc is not detected in water. Lead in water is not detected after 9 hours of sedimentation, and the concentration of manganese by this time is reduced to 0.003 mg / L.

Claims (2)

 1. METHOD OF WASTE WATER TREATMENT FROM HEAVY METALS, including sorption on a carrier with immobilized microorganisms, characterized in that oxidized coal is used as a carrier, and a mixture of microbial cultures Acinetobacter coaleoauficus, Pseudomonas pseudomonasome 1 denitific is used as a microorganism 1, moreover, in the process of immobilization, first phosphorite flour is added to coal in an amount of 1 g per 50 g of coal, and after stirring, slaked lime is added to pH 7.  2. The method according to p. 1, characterized in that the sorbent is added in an amount of 100-250 g per 1 g of metal contained in wastewater.

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