RU2728453C1 - Method of producing plant products environmentally safe by heavy metals content when using waste water sludge on fertilizer - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to agriculture, namely to a method for production of environmentally safe plant products when using sewage sludge as fertilizer. Method consists in conducting field experiments which are laid with adding to the soil of sewage sludge for agricultural crops in increasing doses – 10, 20, 30 and 40 t/ha of dry mass. Content of heavy metals in plants is determined by chemical method. Depending on their concentration plant products are evaluated as fodder, seed or technical and rational for agricultural utilization of dose of sewage sludge.

EFFECT: rational use of sewage sludge for fertilizer.

1 cl, 1 tbl

Description

The invention relates to the field of agriculture, namely to the use of sewage sludge (WWS) as a fertilizer, taking into account regional soil and climatic conditions. It is known that one of the most important problems of the modern communal services of cities and large settlements is recycling environmentally friendly for the environment and manufactured products. WWS are formed at treatment facilities during the separation of wastewater into liquid and suspended substances. As a rule, the disposal of WWS consists in their burial in special storage facilities, incineration or application for fertilization, if they meet the corresponding sanitary, environmentally acceptable standards in terms of the content of heavy metals (HM). There are many technical solutions aimed at creating technologies for the production of organic fertilizers using this type of waste - sewage sludge as a material for the production of organic fertilizers (AS USSR No. 685653, CL. C05F 11/00, C05F 3/00, 1978 ; USSR AS No. 948993, CL C05F 7/00, C05F 11/02, 1979; USSR AS No. 1213017, CL C05F 7/00, C05F 11/02, 1984; RF Patent No. 2159756 , CL C05F 7/00, 1999; Patent RF No. 2252205, CL C05F 7/00, 2003; Patent RF №2414444, CL. C05F 7/00, 2009; Patent RF №2299872, CL. C05F 7 / 00, 2005, etc.).

The known methods for producing compost using sewage sludge are based on an aerobic method for bioconversion of sewage sludge with moisture-absorbing and gas-absorbing additives (sawdust, peat, wood chips, brewer's grains, straw, etc.), including mixing the components and forming a compost heap from the resulting mixture ... Composting of a mixture (transformation of mixtures into ready-made compost) depends both on the ratio of components, their high-quality mixing, and on factors that contribute to the course of enzymatic processes in the mixture. Biological disinfection of compost is possible as a result of self-heating of the mixture to a certain temperature (50-60 ° C). The introduction of bioactive additives accelerates fermentation.

Known methods for producing compost using sewage sludge are aimed at improving the quality of the resulting compost, reducing its cost, reducing the compost preparation time, but at the same time known methods for producing compost (Pat. RF No. 2159756, CL. C05F 7/00, 1999; Wesner JM Composting sewage sludge. - In the book: Treatment and removal of sewage sludge. - T. 2. - M .: Stroyizdat, 1985, pp. 62-100) are distinguished by low efficiency of removing heavy metals from compost, since the release of heavy metals from the compostable mass occurs only due to the forces of gravity, therefore, heavy metals are retained in the prepared compost, deteriorating the quality of the compost and polluting the environment, some - by the duration of the composting process (AS USSR No. 1213017, CL. C05F 7/00, C05F 11/02, 1984) and high cost (Patent RF No. 2252205, CL. C05F 7/00, 2003).

Thus, it should be recognized that the issues of agricultural use of WWS and composts based on them are extremely insufficiently developed. In Russia, because of this, the use of WWS generated at sewage treatment plants as fertilizer is no more than 5-7%, although the average agricultural utilization of WWS in developed countries is 32% (Strategy for the use of sewage sludge and composts based on them in agriculture. M .: Agroconsult. 2002.138 p.). At the same time, the areas of unauthorized application of WWS are expanding in Russia, including on agricultural land. Therefore, agricultural science faces a difficult task - to establish scientifically substantiated levels of nutrient input in the form of sewage sludge (International Code of Conduct on the Sustainability of Fertilizer Use and Management // Russian Soil Fertility: State and Opportunities. Moscow: VNIIA, 2019. . 202). Since the soil and climatic conditions in Russia differ from foreign ones, it becomes expedient to clarify our own regulations for the use of WWS. At the same time, the various regulations available in Russia on the use of sewage sludge in agricultural production do not agree with each other in terms of permissible doses of their introduction for various agricultural crops, which requires a corresponding revision of these regulations. So, according to the established rules (SanPin 2.1.7.573-96), sewage sludge and composts based on them are allowed to be used for fertilizing land allotted for planting tree and shrub plantations, nurseries, parks, for long-term cultural hay-pasture lands when re-allotted, grain fodder, silage, industrial crops, as well as fallow fields and land reclamation. These rules also determine the temporary maximum permissible levels (MDU-87) of heavy metals in feed for farm animals: in grain and forage, in coarse and succulent feed, root crops. These MRLs do not serve as a limitation in the content of HMs for industrial and seed crops, since the content in their agricultural products cannot have a negative impact on the consumer properties of these products. As for the soil, the specified document contains the approximate permissible concentrations (APC) of heavy metals in soils of various granulometric composition (sandy and sandy loam, clayey and loamy), which should not be exceeded by more than 80% when SS is applied according to the translocation index. At the same time, the specified sanitary and environmental standards (SanPin 2.1.7.573-96, paragraph 3, page 30) differ from the standards according to GOST R 54651-2011 (Appendix B). According to the norms of SanPiN, the permissible dose of precipitation is 10 t / ha, according to GOST, the introduction of precipitation up to 15-20 t / ha is allowed, depending on the fertilized crop.

Another example: Table 1 shows that when SS is applied under barley on sod-podzolic medium loamy soil (Tver region) at a dose of 20 t / ha dry mass, which is not allowed by the recommendations of SanPiN 2.1.7.573-96 (paragraph 3, p. 30), the content of HM in plants turned out to be significantly lower than the standards for the same SanPiN 2.1.7.573-96 (Appendix 17), which indicates a contradiction in the standards given in the same document. Even with the introduction of 35 t / ha dry mass of compost with WWS on soddy-podzolic heavy loamy soil (Moscow region) under perennial grasses, the HM content in plants was also practically below the permissible levels (MDU-87 for fodder crops).

In other words, the introduction of SS in doses from 6 to 35 t / ha of dry mass produced at the treatment facilities of Moscow (Kuryanovskaya aeration station), Tver and Vologda did not cause an excess of HM content in excess of the permissible in various types of plant products - perennial grasses, straw fiber flax, barley grain and potato tubers. And the question remains, what quality of products will be obtained when focusing on the OEC in soils regulated by SanPin 2.1.7.573-96 (Appendix 9), since it is not known what concentration of HM will be in plant products. Moreover, the chemical composition of WWS produced at various treatment facilities, as well as the reaction of plants to the HM content, can differ significantly from the above regulations.

It is for the purpose of scientific substantiation of the permissible doses of WWS for the production of agricultural products for fodder, technical or seed purposes, taking into account the content of TM concentrations in it, at the D.N. Pryanishnikov ”developed a method for obtaining environmentally friendly plant products using sewage sludge for fertilization. The method consists in a comparative assessment of the levels of heavy metals in the biomass of plants introduced into the culture with a proposal for their environmentally safe use for production purposes, depending on the doses of WWS: feed, seed, technical. At the same time, the previously developed MDU-87 cannot serve as a limitation in the content of HM for industrial and seed crops, since their content in agricultural products cannot have a negative effect on the consumer properties of these products and therefore is not regulated by the MDU-87.

The proposed method will increase the use of WWS as a fertilizer from 5-7% of the currently produced volume to 30-40%, i.e. to a level typical for a number of foreign countries.

The proposed method differs from the existing methods of agricultural disposal of sewage sludge by carrying out special field experiments with the introduction of sewage sludge into the soil for agricultural crops in increasing doses. It provides for the establishment of field experiments, timed to specific soil and climatic conditions of treatment facilities and carried out according to the scheme with the following options with increasing doses of WWS: 1. Control (without adding WWS), 2. WWS dose 10 t / ha, 3. WWS dose 20 t / ha, 4. Dose of WWS 30 t / ha, 5. Dose of WWS 40 t / ha. Doses of sewage sludge are given on a dry matter basis of these sludge. When composts are used instead of sewage sludge, the compost doses are increased so that the actual SSV doses correspond to the doses indicated in the field experiment scheme. The amount of heavy metals introduced with sediments or composts based on them is established according to the data of chemical analysis of WWS or composts. The experiment should be carried out in accordance with the generally accepted methodology (BA Dospekhov. Technique of field experiment with the basics of statistical processing of observation results. M .: Kolos, 1965. 335 p.). The area of each plot should be at least 10 m ² , the repetition of the options should be three to four times. If it is supposed to use the site with SS application in the link of crop rotation, then the field experiment continues for several years with a sequential change of cultivated crops in this link or crop rotation as a whole. Based on the results of the experiment, the yield and economic quality of the cultivated crop, the content of heavy metals in plants are determined and, as a result, recommendations are given for the environmentally safe use of fodder, technical or seed products obtained on contaminated precipitation, taking into account its compliance with the MRL. When products containing HM within the limits of the MRLs are obtained in variants of experiments with increasing doses of WWS, it can be recommended for use for feed purposes. In cases where the levels of the MRL are exceeded, the resulting products can only be used as technical or seed products. According to the results obtained, the doses of WWS are regulated to obtain environmentally safe products. For example, when cultivating barley somewhere in the field experiment according to the above scheme of SS application, grain with HM content was obtained in options 1 (without SS application); 2 (OSV dose 10 t / ha); 3 (OSV dose 20 t / ha), corresponding to SanPin 2.1.7.573-96, Appendix 17, and in variants with an application of 30 t / a and 40 t / ha, exceeding these standards. Proceeding from this, the grain in the first three variants, in terms of its quality, can be recommended for use for feed purposes, and the grain obtained in the latter two can be used for seed production or for the production of technical products, in particular, alcohol-containing materials.

The novelty of the proposed method lies in the fact that the reaction of plants to heavy metals is established in field experiments carried out in specific soil and climatic conditions, i.e. in various agricultural regions of the country, which will make it possible to more adequately assess the effect of WWS produced at the treatment facilities of these regions on plants and determine the possibility of their economic use. The technical result is the rational use of WWS for fertilization. To achieve this result, field data are analyzed.

Claims (1)

A method of obtaining environmentally friendly plant products in terms of the content of heavy metals when using sewage sludge for fertilizer, which consists in conducting field experiments, characterized in that field experiments are laid with the introduction of sewage sludge into the soil for agricultural crops in increasing doses - 10, 20, 30 and 40 t / ha of dry mass, then the content of heavy metals in plants is determined by a chemical method and, depending on their concentration, plant products are assessed as fodder, seed or technical and the doses of sewage sludge rational for agricultural utilization are established.