SU1283227A1 - Method of purifying waste water of oil and fat industry - Google Patents

Abstract

The invention relates to the purification of waste oil of fat and fat containing sodium salts of fatty acids and neutral fat, and allows to intensify the filtration process, to improve the properties of the sludge from the viewpoint of its technological quality and to ensure the possibility of its production as a solid recyclable product. The method is carried out by treating wastewater with carboxymethylcellulose in an amount of 0.05-0.5% and calcium chloride at a rate of 0.5-0.7 mol per 1 mol of sodium soaps at a temperature of 30-5Q C, followed by stirring the mixture for 30 - 90 minutes and filtering the formed insoluble calcium soap and neutral fat adsorbed on it; The isolated precipitate is dislodged with a tartar soap, the product of oyster tars from the distillation of fatty CES-. lot, isolated from oils and fats, in the ratio (1: 0.5) - (: 2) to calcium soaps, containing contents in the sediment, and hydroxide is introduced with an excess of 0.03-0.3%. After the saponification of the fat, the precipitate is vacuum dried at a temperature of 90-PO C and a residual pressure of 2.0-2.6 kPa. ZP; f-ly, 2 tab. g

Description

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The invention relates to the purification of wastewater from oil and fat industry, namely wastewater, the refining of fats and vegetable oils, as well as podmylny liquors, which are formed during the production of toilet and household soap.

The purpose of the invention is to intensify the filtration process and improve the degree of sludge dewatering.

The method is carried out in the following manner.

Fatty acid wastewater containing sodium salts of fatty acids and neutral fat is injected with carboxymethyl cellulose (CMC) in an amount of 0.05-0.5%, the mixture is treated with a 20-40% aqueous solution of calcium chloride at the rate of 0, 5-0.7 mole per I mole of sodium soaps contained therein. If caustic soda and sodium carbonate are present in the water to be treated, an additional amount of porous calcium is added at the rate of 0.5 mol per 1 mol of sodium hydroxide and 1 mol per 1 mol of sodium carbonate. After treatment, the mixture is incubated for 30-90 mi and filtered. The filter residue is an insoluble calcium soap with neutral fat adsorbed on it. The isolated precipitate is further mixed with the tar soap - the product of the tar removal from the distillation of fatty acids isolated from oils and fats, in a ratio of 1: 0.5-1: 2 to calcium soaps contained in the filter residue. The resulting mixture is treated with a solution of sodium hydroxide and a saponification of fats contained in the filter residue, providing an excess of alkali in the mass in the range of 0.03-0.3%. After saponification, the precipitate is dried in a vacuum drying unit pr, 90-10 C and a residual pressure of 2.0-2.6 kPa to a moisture content in the dried product of 20-30%.

The introduction of carboxymethylcellulose (SHC) into the wastewater before treatment with calcium chloride makes it possible to increase the filtration rate and the plasticity of the filter sludge obtained due to the additional fat coagulation and the increase in its adsorption on calcium mints.

Adding CMC less than 0.05% does not lead to a positive effect, and the introduction of the reagent

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Above 0.5%, it boils in co (.t, filterable solutions and impairs purification.

The introduction of calcium chloride in an amount less than 0.5 mol per 1 mol of sodium Mi.ui contained in the mixture does not ensure complete conversion of sodium salts into calcium mines, and an increase in the amount of calcium chloride more than 0.7 mol per 1 mol of sodium Soaps are not so convenient because they do not affect the speed and completeness of the conversion of sodium salts. Moreover, an excess of calcium chloride does not increase the chloride content in the purified waste water.

In the presence of caustic soda and sodium carbonate in wastewater, it is necessary to introduce an additional amount of calcium chloride solution at the rate of 0.5 mol of calcium chloride per 1 mol of caustic soda and 1 mol of calcium chloride per mol of soda.

It takes at least 30 minutes to form a precipitate of calcium soaps, an exposure time of more than 90 minutes lengthens the duration of the wastewater treatment process, without affecting the degree of their purification.

The introduction of residual tar into the filter improves its rheological properties and provides the possibility of dewatering, for example, in a vacuum-drying unit. When the ratio of calcium soaps in the filter residue to tar soaps is less than 1: 0.5, it is difficult to obtain a uniform suspension for feeding the mixture through the nozzles to vacuum drying. When the ratio is more than 1: 2, the viscosity of the suspension increases, making it difficult to supply the mixture to a vacuum dryer and reduces the productivity of the vacuum dryer.

The mixture of sludge and filter soaps is treated with caustic soda to make the mixtures containing fats. In order to avoid thickening of the mass and the formation of dense clods, it is necessary to provide an excess of caustic soda in the range of 0.03-0.30%.

The resulting mass, containing 50-60% of moisture, is dried in a vacuum-drying unit at a residual pressure of 2.0-2.6 kPa and a temperature of 90-110 ° C. This drying mode allows you to get soap chips that have a convenient commodity

form. At temperatures below 90 ° C, the mass is not technological because of the high viscosity, higher than PO C, thermal oxidative destruction of the product occurs. To ensure a solid consistency, drying is carried out until the moisture content of the product is 20-30%.

Example. To 1 ton of wash water after refining an oil containing 1% neutral fat, 1% sodium salts of fatty acids and 0.03% sodium hydroxide, add 2.5 kg of carboxymethylcellulose, 7.61 kg of 35% calcium chloride solution for the transfer of sodium soaps to calcium and 1.19 kg of solution to the interaction of calcium chloride with sodium hydroxide. The treatment of water with calcium chloride is carried out at 35 ° C. The reaction mixture was formed, the flakes were kept for 30 minutes, after which the reaction mixture was slowly pumped to the filter press with slow stirring. The precipitate of; the filter is mixed with 12.38 kg of tar soaps (the product of tar tar from the distillation of fatty acids) and 6.0 kg are added. AO% sodium hydroxide solution for saponification of fat, providing an excess of alkali in Macde no more. The resulting mass is dried in a vacuum-drying unit at a 90- and residual pressure of 2.0-2.6 kPa to a moisture content of soap chips of 20-30%,

In tab. 1 and 2 are technological parameters and indicators. purification of fat-containing wastewater, followed by sludge treatment. .

Physical and chemical indicators of wastewater treatment concentrate: mass fraction of fatty substances is not less than 30.0%; mass fraction of free caustic alkali is not more than 0.3%; mass dale of moisture is not fighting 30.0%; mass fraction of mineral salts, not more than-25.0%; appearance - strzgzhka thickness of not more than 0.8-1.2 mm; consistency - hard, not sticky to the touch; color from light brown to dark brown

Milya; There are no streaks in the water, pos832274

vogo; the smell is weak, partially soluble; rovzryvobezopasny. .

The use of the proposed method of wastewater treatment in comparison with the prototype makes it possible to increase the productivity of the process by intensifying the filtration stage and increasing the degree of sludge dehydration. To obtain a filter residue in the form of a solid product of the commodity form, which in turn ensures the rational use of the valuable components contained in the drains of fat and debris.

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Claims (1)

1. A method for purifying wastewater oil mash-up, containing sodium soap and neutral fat, including their treatment with a solution of calcium chloride at a higher temperature to form a calcium salt, mixing the resulting mixture, filtering, precipitating, dehydrating and utilizing In order to intensify the filtration process and improve the degree of sludge dewatering, carboxymethylcellulose in the amount of 0.05-0.5% is introduced into the wastewater before being treated with calcium chloride. nio is carried out for 30-90 min, and the precipitate was treated with  tar mixture in the ratio of 1: 0.5- -1: 2 to calcium soaps, content in the sediment, is washed by the introduction of sodium hydroxide with its excess in the range of 0.03-0.3%, and then subjected to vacuum drying at a temperature of 90-11 and a residual pressure of 2.0-2, 6 kPa. 2, the method according to p. Calcium chloride leads g and. EO-50 C at the rate of 0.5 gO, 07 mol of calcium chloride per I mol of sodium and msec. .I V .a about but but F o and {- H {- -1 1 | th & (, bio Igesee Jiihsbe and names 11 i. lllii but | 5 a o) a o to ft c. BUT ft L I K O b " 1121 i oh | p VES & ilsl U Q with e "9 K and in b sts-l & .sbs "i I k, gi; | l | sj, 8 gzh sallHgf ilii iimifii 4 iliil. Slgfiib Hill || M 7  "AZ 8532 Th III If eleven and§ 4 N I am 8 drink I go (h h ABOUT and- ABOUT ABOUT 1P about f with IN NOO iM "h Oh oh about about g at " Si " pch and go " 1L. about BUT about U-, p about f - her with g about 1O  chd L O O O O O O O. “-a; Ltd O 1L o 1L o o p 1L "l about sh about l about about f4 p l P1 W gp  about o t j i g 1L "l 1L 1L" " о о р о ii cГ  e n 1 ivO “9 O O O O O O O (L 1L o o o o about N -. D I o o o o o o o h §32 MS m V, lg | g . table 2