RU2526983C2 - Recultivation of slurry reservoirs of bleached sulphate cellulose manufacturers - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to environmental protection and can be used for processing of wastes of bleached sulphate cellulose production with application of sulphate process. Recultivation of slurry reservoirs comprises removal of slurry water, application of the later of burnt coal ash on reservoir surface, ash being neutralised by store in ash ponds to acidity of ash aqueous extract pH 7.0-8.0.Slurry-to-ash ratio is selected to make 1:1-2:1. Said materials are mixed layer-by-layer, water released at their interaction is removed to get ash-slurry-lignine substrate.

EFFECT: improved environmental protection, lower decontamination costs, higher quality of treatment, recycling of processed wastes.

2 cl, 1 tbl

Description

The invention relates to environmental protection and can be used for the safe reclamation of industrial waste cards generated during the treatment of wastewater from bleached pulp enterprises using the sulfate method. The invention can be used for reclamation of disturbed lands, elimination of hazardous waste landfills while recycling large-scale waste of the power system - ash from burning coal.

The Baikal Pulp Mill (BPPM) is an object that poses a real threat to the ecosystem of Lake Baikal. Sludge collectors of this enterprise, containing about 6.2 million m ³ of lignin sludge, are dangerous for Lake Baikal due to the influx of pollution into groundwater, due to overflow of sewage over the edges of dams during storm showers. Slurry maps are located in close proximity to the World Heritage Site - Lake Baikal. Work to prevent mudflow hazard was not carried out after 1972. In a catastrophic village, the discharge of organic components into Lake Baikal is equivalent to the dumps of the plant for 700 years [A. Suturin. The Baikal ecosystem can be destroyed by industrial waste // Ecology and Life. - 2012. - No. 2, - p. 82-83] [1].

Lignin sludge is formed during the operation of wastewater treatment plants of enterprises producing bleached pulp according to the sulfate method. The cleaning technology used at these facilities includes chemical treatment, in which impurities are precipitated by adding aluminum hydroxide and coagulation-promoting substances, and biological treatment carried out by contacting the wastewater with microorganisms and then settling in settling ponds. Insoluble substances formed at the stages of chemical and biological purification are lignin sludge - a jelly-like product with a high water content (up to 95%).

The main negative characteristics of this waste are high humidity (more than 90%), the formation of a large amount of toxic and odorous gases in the cards during its storage: hydrogen sulfide and methyl mercaptan, and the presence of organochlorine compounds.

The problem of reclamation of sludge collectors at BPPM has not been resolved for more than 30 years. Over the years, various technologies have been proposed to eliminate this source of pollution, but not one of them has solved the existing problem. Projects offered filling the cards with sludge-lignin with construction waste, filling the cards with artificial soil, offered drying and burning sludge-lignin in furnaces, using iron trichloride to deodorize the gases released, filling the cards with ash pulp, and self-growth. They tried to solve the dehydration of the slurry-lignin in the maps by freezing. [Report 2 under the contract RG-12-23GK / 98 of 10/17/11 on the topic: Inventory of the Baikal natural territory, which has accumulated environmental damage associated with past economic activities. - Irkutsk: Establishment of the Russian Academy of Sciences Limnological Institute of the Siberian Branch of the Russian Academy of Sciences. - 2011] [2].

In the sixties, it was assumed that the lignin sludge stored in the maps in the winter would freeze, dehydrate in the spring, and condense. Without special winter spraying procedures, lignin slurry does not dehydrate it in the cards.

It was proposed to reclaim cards with lignin sludge filled with sawdust. This method does not provide dehydration of sludge-lignin and its deodorization. Not implemented the method also due to the lack of a proportionate amount of sawdust.

One of the most common reclamation methods is to leave sludge collector cards for “self-growth”. Such artificial bogs retain lignin sludge almost to the same degree of moisture, without any vertical compaction of lignin sludge, with the formation of hydrogen sulfide, methyl mercaptan and methane. All map material during floods and mudflows can be carried to water bodies.

The use of ash pulp from thermal power plants to cover maps is unacceptable, since the alkaline nature of the water-ash pulp only contributes to the transition of sludge-lignin to the colloidal state, and chlororganics to the solution.

Natural dehydration of sludge-lignin in maps without a mirror of supra-slurry waters was proposed. In this case, only the upper 30-centimeter layer of sludge-lignin dried out, and the dried and cracked surface of the cards became fire hazard.

It was proposed to export lignin sludge from cards, drying in centrifuges and filter presses, followed by burning in special furnaces with the addition of petroleum products. Already at the stage of preparation for incineration, lignin sludge from the sedimentation maps emits such an amount of hydrogen sulfide that its concentration in the working zone exceeds the MPC by 5-6 times.

The proposal for the burning of lignin sludge from cards in plasmatrons, special furnaces is not implemented due to excess waste moisture, significant cost, the need for preliminary drying and incinerators, the estimated duration of complete sludge burning [2].

The combustion product of sludge-lignin is proposed to be used in building materials and as a coagulant in wastewater treatment [Patent No. 2136599 of the Russian Federation IPC C02F 1/28. The method of wastewater treatment / Leonov S. B and other ISTU - Publ. 09/10/1999] [3].

The cost characteristics of the proposed raw materials for concrete and coagulants make these proposals unprofitable. The duration of the project is decades.

Various projects for the disposal of lignin sludge in building materials are able to use only a small part of industrial waste. The proposed methods for reclamation of cards and disposal of sludge-lignin do not provide for the disposal of all pulp and paper products.

A known method of composting sewage sludge contaminated with heavy metals. The method includes mixing sediments with additives, forming a compost heap using layers of additives to localize metal-bearing compounds [Patent No. 2159756 of the Russian Federation, IPC C05F 7/00. The method of composting sewage sludge / Grishin V.Kh. - Publ. 11.27.2000] [4].

Known methods for the disposal of sewage sludge by composting involve heating the initial mixture by using an additional component, such as peat, or by creating a special thermal regime. Production requires a long time and is not applicable for the disposal of slurry cards.

A known method of producing organic fertilizer, in which solid waste is mixed from the production of cellulose and paperboard, cattle or manure with the addition of ash from burning brown coal to obtain compost mixtures [RF Patent No. 2086521, IPC C05F 11/00. A method of obtaining organic fertilizer / Suturin A.N. and other Limnological Institute SB RAS - Publ. 08/10/1997] [5].

The known method for stabilization of the jelly-like lignin sludge and further remediation of sludge storage cards is not suitable.

A known method for the preparation of sludge with its removal from storage sites, including keeping it until freezing for dehydration, covering the surface of the sludge with a layer of vegetable waste, keeping it until the structure of the sludge changes, introducing a layer of vegetable waste, mixing and then re-covering the mixture with vegetable waste, re-mixing and further processing [Patent No. 2421289 of the Russian Federation, IPC B09B 3/00, C02F 11/00, B09C 1/00. The method of preparation of sludge / Naumova R.P. and etc.; Naumova R.P., Nesmelov A.A., Grigoryeva T.V. and State Educational Institution of Higher Professional Education “Kazan State University named after Ulyanov-Lenin "- Publ. 06/20/2011] [6].

The known technology does not solve the problem of the disposal and disposal of such large-tonnage and complex waste, such as lignin sludge from enterprises for the production of bleached sulfate pulp, is labor-intensive, time-consuming and inefficient.

As the closest analogue, we can consider the article of one of the authors of the claimed technical solution, which published information on the work carried out by the applicant at the initiative of the Ministry of Natural Resources of the Russian Federation to inventory accumulated environmental damage in the Baikal natural territory [Suturin A.N. The Baikal ecosystem can be destroyed by industrial waste // Ecology and Life. - 2012 - No. 2, - p. 82-83] [1].

As a result of the work carried out, it was found that when coal ash and lignin sludge are mixed in equal volumes, waste dehydration occurs, while the released water is diverted to treatment facilities.

The claimed technical solution was implemented in the development of a set of measures to eliminate environmental damage as a result of past production activities of the Baikal PPM.

The technical result of the invention is to eliminate the negative impact of the waste of the enterprise producing cellulose according to the sulfate method on the natural territory, reduce the cost of neutralizing sludge-lignin, reduce further pollution of environmentally vulnerable areas and air, expand the possibility and quality of further processing of dehydrated and decontaminated sediments.

The technical result provides a method including applying a layer of material to the surface of a storage card of a sludge-lignin, which is used ashes from burning coal, mixing ash and sludge-lignin, removing released water, characterized in that the sludge is first removed from the surface of the card, use ash neutralized as a result of storage in ash pits to the state of the acidity index of the aqueous extract of ash pH 7.0-8.0, while the volume ratio of sludge and ash is selected in the range 1: 1-2: 1. The indicated materials are mixed in layers and after removal of the water released as a result of their interaction, a consolidated ash-sludge substrate is obtained.

The method uses coal ashes with a total Al ₂ O ₃ content _of more than 20% and an amount of Fe ₂ O ₃ in the range of 5-10%, with an unburned coal content of more than 2%.

The method of reclamation of sludge collectors of waste from enterprises for the production of bleached sulfate cellulose can be used for further biological remediation of the territory.

Before applying the ash, the sludge collector card is drained from the sludge waters generated from seasonal precipitation. Application of ash is carried out on the surface of the map in sections in layers. Push it into the area with simultaneous mixing with the bottom layer of sludge-lignin and moving the resulting mixture, with the removal of the water formed during this. The mixed mass is shifted off the site and again on the lower layer of sludge-lignin, a layer of ash material is applied with mixing of the layers and its shift until the complete production of sludge-lignin. The developed section of the sludge collector card is filled with the formed ash-sludge mixture with compaction of the surface layer.

The stable composition of the filled ash-sludge mixture of the map ensures its resistance to the effects of showers, landslides and mudflows. The resulting mixture is fireproof.

Regions reclaimed in this way can be further used as a basis for objects of various purposes.

Further biological remediation of these areas is possible. For this, the stabilized areas are covered with a layer of a mixture of wood bark and ash with the addition of a preparation containing soil microflora with the formation of a vegetation cover on the prepared surface.

The ash composition from burning brown coal and the effect of ash on the chemical composition of the soil, plants and soil biota are well known. The rich macro- and microelement composition of coal ashes makes it possible to use them as a meliorant of acid soils [Effect of Irsha-Borodinsky coal ashes on the chemical composition of soil, plants and soil biota / Boyko S.M. and others // Agrochemistry. - 1996 - No. 5. - S.73-82. [7]; The use of low-calcium ash of brown coal of the Azeyskoye deposit as a complex ameliorant of gray forest soils / Kulikova NN and others // Agrochemistry. - 1999. - No. 6. - S.21-27. [8].

As a result of research work on the reclamation of sludge collectors of the BPPM, it was revealed that the ash of coal from the CHPP can serve as the main complex agent for the dehydration, deodorization and adsorption of sludge-lignin. It contains over 30% of glinonozem (dehydration agent). In ash, up to 9% of microparticles of Fe ₃ O ₄ (ferric iron is the best deodorizing agent). Ash has a moisture content of 10-20% and, after mixing with sludge-lignin in a certain ratio by volume, forms a strong consolidated substrate. Unburned coal residues in ashes are similar to activated carbon and adsorb organochlorine from sludge-lignin.

The slurry maps of the Baikal Pulp and Paper Mill are located 7 km from the city of Baikalsk near the river. Solzan. Work on the creation of sludge collectors was performed in the mid 60-ies of the last century. Slurry maps are located on a slope with an average slope of 1.5-2 °. They have an elongated shape with a length of up to 1000 m, a width of 60 to 120 m. These objects belong to hydraulic structures. Structurally, they represent a system of capacities - cards, each level of which is limited by dams. The outer side of the dams is facing Baikal. The inner side and the bed of sludge collector cards are made in the form of a clay castle. There is a system for discharging excess water, the discharge of which occurs as it accumulates.

The possibility of implementing the proposed method is confirmed by the following descriptions of laboratory and field experiments.

Example 1

Before conducting experimental work on maps, lignin sludge and ash from the ash dump for the content of heavy metals and radioactivity indicators were investigated. Samples taken from maps at the end of winter showed the following horizons in a vertical slice of map No. 6: snow cover 0.8-1 m, ice 10-12 cm, water 10 cm, liquefied gel-like lignin sludge - 4 m, and then compacted layer 10-15 cm.

The interaction of sludge-lignin with ash was first studied in the laboratory. Ash and lignin sludge were taken in a ratio of 1: 1 by volume.

The moisture content of sludge-lignin was 93%; it had a strong specific odor due to the presence of methyl mercaptan, hydrogen sulfide, and other sulfur-containing compounds. Ash was taken from the ash dump of the Baikal Pulp and Paper Mill TPP. The components were mixed in transparent glass vessels. Even visual observation almost immediately showed an improvement in quality indicators. Water was displaced from the formed mixture — dehydration of sludge-lignin. The smell has disappeared. Aerobic conditions formed in the mixture after removal of water contributed to a change in the chemical composition of sludge-lignin. Analysis of the mixture showed the formation of oxide forms of metals, the fixation of mobile metal ions. Chlorophenol-containing compounds after exposure to the complex of aluminum from ash on heavy metals are subject to destruction. The aluminum content in the mixture increased from 20% to 25%, cobalt from 1.5X10 ^-3 % to 8X10 ^-3 %, calcium from 4% to 6%, potassium from 4% to 6%. The experimental data showed that many elements either are fixed in complexes in fixed forms, or leave the substrate with the formed water.

Example 2

Phytotoxicity of BPPM wastes and substrates based on them was evaluated by the method of seedlings in laboratory conditions. Polyethylene containers were filled with waste or substrates from the waste of BPPM with the initial humidity. The options were laid: Sl - lignin sludge; Z - ash CHP; K is the bark; Шл + З - sludge-lignin and ash of thermal power station; З + К - ash of thermal power station and bark; З + Шл + К - ash of thermal power station, lignin sludge and bark. The waste was mixed in a volume ratio of each component 1: 1. The experiment was carried out in six replicates, with half of the waste and substrates from them being treated with a complex microbiological preparation containing soil microflora. In this case, the Baikal EM1 preparation was used. The seeds of watercress (Lepidium sativum L.), which is sensitive to the presence of toxic substances, characterized by rapid germination and growth, were used as a biotest.

The results of the influence of the substrates from the waste on the germination of watercress seeds are shown in the table. In the variants of the experiment with treatment with a microbiological preparation, an increase in sprouted seeds was noted in the vessel with BCPB bark and in the vessel with a mixture of sludge-lignin with ash with the addition of bark. The shortest roots, stems and minimal biomass of watercress were observed in samples containing one lignin sludge.

Example 3

The obtained experience and results were used when laying the experiments on map No. 6 of the BPPM sludge collector.

For this purpose, ash from thermal power plants with a density of 0.8-12 cm ³ with a moisture capacity of 21 to 35% were delivered to the inter-section section, and bark was a waste from the main production of BPPM. The following plants were selected as phytomeliorants: Jerusalem artichoke, reed canary, Highlander of Weirich of Transbaikal, curly malva and amaranth. The amount of ash to the volume of sludge-lignin was added in a ratio of 2: 1. Stirring was carried out to a depth of more than 40 cm. The released water was discharged into the wastewater treatment system. The mixture was covered with a layer of bark while mixing it with an ash-lignin substrate. For control and comparison, sites were prepared for landing on sludge-lignin without additives after discharge of meteoric water, on sludge-lignin with ash and the addition of mineral fertilizer (NPK) and on sludge-lignin with the addition of mineral fertilizer.

Planting phytomeliorants in the experimental plot was made in early June. When planting Jerusalem artichoke, they used the Interest variety.

In the initial period, friendly seedlings were noted on all variants, since at this stage the plant spends its storage substances. During the branching phase, a significant difference appeared between plants in different areas. The number of shoots in the area with ash, bark and the introduced microbiological preparation (section 2) was the largest, and the height of the plants exceeded their height in the area with sludge-lignin (control) by 20-25 cm. When observing the growth and development of plants, a good branching of Jerusalem artichoke, the highest growth (90-100 cm) and the largest diameter of the stems (2.0-2.2 cm) in plants in section 2. While the control plant height was 25-30 cm, with a thickness ( diameter) of the stem 0.5-0.8 cm. In September, in all areas except the control (sludge-lignin), cl kill me. In section 2, the mass of tubers was greatest. Among the reclamation herbs, the mountaineer of Weirich of Transbaikal showed the best survival rate and development of the root system to the lower layer of lignin sludge. A powerful formation of the root system in section 2 was found in the cane cane. Conducted experimental plantings showed the real possibility of biological reclamation of waste BPPM.

The invention can be successfully used to improve contaminated land with the simultaneous disposal of other industrial wastes from the pulp and paper industry: coal ash and wood bark.

Reclamation of BPPM sludge-lignin cards using the proposed method will allow to remove ash from its storage cards (Babkhinsky polygon), release them for recreational purposes, reclaim the Solzansky polygon cards and carry out further remediation of the territory in any rational way.

Table Method for reclamation of sludge collector cards of bleached sulfate pulp enterprises 10/31/2011 11/01/2011 11/2/11 11/07/11 11/08/2011 11/09/2011 11/10/11 Options The number of seedlings Day 7 average Repetitions Without B-EM1 I II III I II III I II III I II III I II III I II III I II III Shl 0 0 0 0 one 0 0 one 0 0 one 0 0 one 0 0 one 0 0 one 0 0.3 3 0 3 four four 5 6 four 8 9 four 9 9 5 9 9 5 9 9 5 9 9 8 Shl + Z 0 0 one 0 0 one 0 0 one 0 0 one 0 0 one 0 0 one 0 0 one 0.3 TO 2 3 2 four four four 5 6 6 5 9 7 5 9 8 5 9 8 5 10 8 8 Shl + K 5 four 6 5 6 6 5 8 9 6 8 9 7 8 9 7 8 9 7 8 10 8 S + Shl + K one 0 0 one 0 0 2 0 0 2 0 0 2 0 0 3 0 one 3 0 one one + B-EM1 I II III I II III I II III I II III I II III I II III I II III Shl 0 0 0 0 0 0 0 0 0 0 0 one 0 0 one 0 0 one 0 0 one 0.3 3 four 0 0 6 0 0 8 0 one 8 0 3 8 0 four 8 0 four 8 0 four four TO 7 four 3 9 6 7 10 8 7 10 10 7 10 10 7 10 10 9 10 10 9 10 Shl + Z 0 0 0 one 0 0 one 0 0 one 0 one one 0 one 2 0 one 2 0 one one Z + K 2 2 four four 2 6 5 four 8 6 5 9 6 5 9 7 5 10 7 5 10 7 S + Shl + K 0 0 0 0 0 one 0 0 one 3 one 5 3 one 5 3 3 5 3 four 6 four

Claims (2)

1. The method of reclamation of sludge collector sludge collectors of bleached sulphate pulp enterprises, including applying a layer of material to the surface of the sludge collector card, using ashes from burning coal, removing released water, characterized in that the sludge is first removed from the surface of the card water, ash is used from burning coal, neutralized as a result of storage in ash pits to the state of the acidity index of the aqueous ash extraction, pH 7.0-8.0, while the volume ratio Lama and the Ash chosen in the range 1: 1-2: 1, stirring was conducted layering these materials and, after removal of water liberated as a result of their interaction, give Zolo-shlamligninny substrate. 2. The method according to claim 1, characterized in that coal ashes with a total Al ₂ O ₃ content _of more than 20% and an amount of Fe ₂ O ₃ in the range of 5-10%, with an unburned coal content of more than 2% are used.