RU2736648C1 - Method of producing organic ameliorant - Google Patents

Abstract

FIELD: ecology; land reclamation.

SUBSTANCE: method involves reagent treatment of sewage sludge with subsequent composting. Wastewater sludge used is excess active sludge from aerobic biological treatment of waste water from sulphide pulp and paper industry. Reagent used is a sewage sludge of sulphide pulp-and-paper industry with lignin fiber content in a weight ratio of 3-4:1, and is dehydrated to 80 %. Then the substrate is mixed, and aerobic composting is performed for at least 30 days, and then obtained substrate is mixed with light loamy soil at a weight ratio of light loam soil content of 70 to 80 % and obtained substrate from 30 to 20 %. Obtained organic ameliorant is ground in hammer crusher.

EFFECT: method provides creation of ecologically clean product capable to accelerate process of overgrowing of restored territory.

1 cl, 1 dwg, 2 tbl

Description

The invention relates to the field of ecology and nature restoration, can be used to obtain an organic soil-soil mixture of prolonged action during land reclamation in forestry, sanitary and hygienic and construction areas.

There is a known method of obtaining technogenic soil (patent RU No. 2497784, publ. 11/10/2013), which consists in mixing sludge with powdered lowland peat at a mass ratio of 1: (1.7-1.8), followed by processes: solid-phase fermentation-composting in piles with periodic tedding and mixing to obtain biocompost at a humidity of 50-55% and mixing with excavated soil (based on cover and alluvial loams and fluvioglacial sands) - the ratio to silt sediment (2.2-2.3): 1.

The disadvantage of this method is the process of periodic tedding of powdered lowland peat, in which the access of oxygen leads to drying out and loss of nutrient, organic substances of peat.

There is a known method of producing granular organomineral fertilizers ("ILOPLANT") (patent RU No. 2702164, publ. 04.10.2019), which includes the treatment of sewage sludge with a solution of nitric acid, neutralizing the acidity of sewage sludge with an alkaline agent, subsequent grinding, moistening, magnetic separation of sludge wastewater, mixing the treated wastewater sludge with mineral additives, placed in at least two consumable silos, in each of which the additives are aerated, after which the mixture is granulated and packed.

The disadvantage of this method is the multicomponent composition of the proposed organomineral fertilizer, which complicates the process of creating homogeneity in the substrate - insufficient mixing of the components can lead to a local increase in acidity or alkalinity unacceptable for plants.

A known method of processing organic wastewater sludge (patent RU No. 2210550, publ. 20.08.2003), which consists in mixing raw organic sludge with excess activated sludge at a ratio of 1: 1 to 1: 3, followed by the process of multiple cavitation treatment of the mixture during 9-12 hours with the number of circulation cycles 3-10 at a cavitation number of 0.01-0.05 in conjunction with aerobic stabilization and ejection aeration, as well as the addition of over-silt water (1/3 of the volume) and compaction.

The disadvantage of this method is the multistage technological process of treating sewage sludge, the presence of pathogenic microorganisms in the final material and an unpleasant odor.

There is a known method of obtaining organomineral fertilizers from sewage sludge using composting (patent RU No. 2489414, publ. 08/10/2013), which consists in mixing urban sewage sludge with filler, baking powder and detoxifier - pine sawdust. Pine sawdust (fraction size up to 2 mm) and municipal waste water sludge (fraction size up to 5 mm) are mixed in a mass ratio of 1: 0.5, followed by composting.

The disadvantage of this method is the long composting process and the potential negative impact of sawdust, the inclusion of sawdust in the composition can lead to a deficiency of nitrogen in the soil and an increase in soil acidity.

A known method of obtaining organo-mineral fertilizers from urban wastewater sludge (patent RU No. 2556721, publ. 07/20/2015), taken as a prototype, consists in reagent treatment of urban wastewater sludge followed by composting of the mixture, as a reagent used organo-mineral composition containing calcium oxide and low-lying peat (in a mass ratio to urban wastewater sludge equal to (OSV 25-75) :( 2-3.5): 10), with composting of the sludge for at least 7 days in air.

The disadvantages of this method include the use of urban wastewater sludge, which is characterized by high concentrations of heavy metals and pathogenic microorganisms.

The technical result is the creation of an environmentally friendly product capable of accelerating the process of overgrowing the restored territory.

The technical result is achieved by the fact that excess activated sludge from aerobic biological wastewater treatment of the sulfide pulp and paper industry is used as a wastewater sludge; as a reagent, wastewater sludge from the sulfide pulp and paper industry with a lignin fiber content is used, in a mass ratio of 3-4 : 1, dehydrate to 80%, then the substrate is mixed and aerobic composting is carried out for at least 30 days and then the resulting substrate is mixed with light loamy soil at a ratio by weight of light loamy soil from 70 to 80% and the resulting substrate from 30 to 20% , the resulting organic ameliorant is ground in a hammer mill.

The method is illustrated by the following figure:

1 is a graph showing changes over time: humidity ( W ), acidity ( pH ), carbon to nitrogen ratio (C: N) and temperature range at different possible values.

The method of obtaining is as follows. Excess activated sludge from aerobic biological wastewater treatment of the sulfide pulp and paper industry in parallel with the reagent - wastewater sludge from the sulfide pulp and paper industry (containing lignin fiber) is fed into an intermediate tank to mechanical dewatering apparatus for mixing at a weight ratio of 3-4 :1. The resulting substrate is mechanically dehydrated to 80%, before free water is removed.

The dehydrated substrate is mixed, composted aerobically for at least 30 days until the outer shell of the lumpy aggregates of the substrate is air-dry, if necessary, additional periodic mixing is performed.

The dehydrated substrate is mixed with light loamy soil at a ratio by weight:

- light loamy soil from 70 to 80%;

- dehydrated substrate from 30 to 20%.

The resulting organic ameliorant is ground in a hammer mill until the distribution of the components in the composition is uniform. The resulting organic ameliorant has the following properties: increases seed germination, accelerates linear growth and increases the growth of biomass of grass mixtures.

The method is illustrated by the following examples. To assess the reliability of the proposed method for obtaining an organic ameliorant, excess activated sludge from aerobic biological wastewater treatment of the sulfide pulp and paper industry, formed at the stage of aerobic biological wastewater treatment of a pulp and paper mill of the sulfide cooking method, was taken as a wastewater sludge, which is watered sludge of a curd mass of gray-brown color with inclusions of cellulose fiber and alumina, lime, having a slightly acidic reaction of the medium, as a production waste related to the IV-V hazard class.

As a reagent, the wastewater sludge of the sulphide pulp and paper industry (with the content of lignin fiber), formed at the stage of mechanical wastewater treatment from the production of sulphide cellulose (with the content of lignin fiber), which can vary within 50-90%, was taken. The sludge of the sulphide pulp and paper industry is a watered sludge (with a moisture content of more than 60%) containing possible organic impurities (cellulose and lignin fiber) and traces of mineral impurities, as a production waste, belongs to the IV-V hazard class.

To create an optimal substrate density, speedy drying and prevent decay processes, the components were dehydrated to 80% (before free water was removed) and mixed at a mass ratio of 3-4: 1.

At average values of the density of the sludge of sulphide pulp and paper industry (containing lignin fiber) air-dry state.

After mixing the main component - excess activated sludge from aerobic biological wastewater treatment of the sulfide pulp and paper industry and a reagent - wastewater sludge from the sulfide pulp and paper industry (containing lignin fiber), the formed substrate was left on the temporary storage site for at least 30 days in a well-ventilated temporary storage area for aerobic composting and drying to an air-dry state of the outer shell of lumpy substrate aggregates.

The minimum number of days of composting is due to the need to stabilize the substrate at the end of intensive biochemical processes. The dependence of the change over time: humidity ( W ), acidity ( pH ), the ratio of carbon to nitrogen (C: N) and temperature range at different possible values of C: N and W are shown in Fig. 1.

Samples were taken from the formed substrate - excess activated sludge from aerobic biological wastewater treatment of the sulphide pulp and paper industry and sludge from the sulphide pulp and paper industry (containing lignin fiber), the results are presented in Table 1.

Table 1 - Characteristics of the substrate

Indicator name Characteristic 1. Appearance and color A tiny gray-brown mass 2. Mass fraction of moisture,% 70-80 3. Acidity, pH of aqueous suspension 5.0-7.0 Nutrient content,% 4. Content of organic matter,%, up to 90.0 5. Total nitrogen,% 0.30-0.40 6. Phosphorus,% 0.10-0.20 7. Calcium,% 7.8-8.0 Heavy metal content, mg / kg Zinc, mg / kg 430 Copper, mg / kg 210 Cadmium, mg / kg, no more 2.0 Lead, mg / kg, no more 130 Arsenic, mg / kg, no more ten Nickel, mg / kg, no more 80 Content of viable pathogens of parasites (eggs and larvae of geohelminths, cysts-oocysts of pathogenic protozoa), units per 100 g absence Content of pathogenic microflora, including salmonella, CFU / 50g absence

Organic matter from excess activated sludge provides conditions for a nutrient regime of rapid supply, which makes it possible to form microorganism communities in the restored technogenic soil to normalize the self-healing function of the ecosystem, and the organic component of the sludge, which includes lignin, has a prolonged effect on the nutrient regime of the soil environment.

The high calcium content promotes the formation of soil aggregates, improves the structure and porosity of the soil, which accelerates and increases the efficiency of the functions of soil restoration and formation.

For the proposed method of obtaining an organic ameliorant, a light loamy soil is used (the content of clay inclusions is from 20 to 50%) from territories related to the reclaimed land area to simplify the migration of characteristic species of phytocenoses. Due to its density, light loamy soil is a structural framework for a substrate of excess activated sludge from aerobic biological treatment of wastewater from the sulphide pulp and paper industry and wastewater sludge from the sulphide pulp and paper industry (containing lignin fiber), providing optimal conditions for water, air, salt, acid and nutrient regimes of the reclaimed land area.

To assess the practical implementation of the ameliorant, a light loamy soil was selected on the territory of the Leningrad region at pH = 6.0-7.0 and the content of mineral nutrients: nitrogen - 50 mg / kg, phosphorus - 150 mg / kg and potassium - 250 mg / kg.

After mixing a light loamy soil and an organic substrate, the mixture is additionally crushed in a hammer mill until the distribution of the components in the composition is uniform.

Studies on the degree of effectiveness of the proposed method of obtaining ameliorant were carried out by modeling artificial soil-ameliorants with an assessment of: reclamation potential, the best ratio and determination of the toxic / nutritive effect of the proposed ameliorant, productivity and growth rate of the aerial part of herbaceous plants.

When determining the potential environmental hazard, a comparative analysis based on the MPC values showed the content of heavy metals within the normal range without the likelihood of a cumulative toxicity effect. In view of the fact that during reclamation work to restore the soil-plant complex there is no repeated application of the ameliorant, the accumulation of heavy metals will not reach the permissible limits.

When modeling soil-ameliorants with an assessment of the reclamation potential, the best ratio and determination of the toxic / nutritional effect of the proposed ameliorant on the productivity and growth rate of the aerial part of herbaceous plants, models of the soil-reclamation layer were formed at various ratios of components with the exception of extreme values that are not suitable for use. The ratios of the components in the ameliorant models (by weight) are presented in Table 2.

Table 2 - Composition of models of the soil-reclamation layer

Reclamation layer model Control model # 1 # 2 No. 3 # 4 Light loamy soil 100% variant of a potentially fertile soil layer introduced during the reclamation of technologically disturbed lands 80-90% 60-70% 40-50% 20-30% Substrate from a mixture of excess activated sludge from aerobic biological wastewater treatment of the sulphide pulp and paper industry and sludge from the sulphide pulp and paper industry (containing lignin fiber) - 10-20% 30-40% 50-60% 70-80%

Models reclamation layer were placed in identical microclimatic conditions: constant temperature at least 20 ^{° C} and relative humidity of 70%, with a uniform lighting and watering respective established conditions.

Based on the research methodology of the influence of various doses of the ameliorant on the growth and development of plants, an assessment of the effectiveness and environmental safety of the proposed organic ameliorant was carried out. The controlled parameters were: germination, linear growth, the rate of development of herbaceous plants and the increase in biomass.

In the model of the reclamation layer, the same number of seeds of wild-growing herbaceous plants found in meadow and forest zones with a temperate climate were introduced: meadow fescue ( Festucapratensis ), meadow timothy grass ( Phleumpratense ), perennial ryegrass ( Loliumperenne ), common bent grass ( Agrostistenuis ).

The results of the germination of seeds confirmed the property of the ameliorant to improve germination: the germination of seeds in the simulated ameliorant-soil in the first 2 weeks exceeded the indicators of the control model by 23-41%.

The results of weekly measurements of the linear growth of plant communities were reflected in a graphical form with the calculation of deviations from the reference and control function of normal conditions for the dynamics of plant growth over time (logistic dependence). The results obtained showed the absence of deviations exceeding 20% from the reference and control models, respectively, the proposed ameliorant is ecologically safe for plant communities.

With a ratio of 70-80% of light loamy soil and 30-20% of the substrate from excess activated sludge from aerobic biological wastewater treatment of the sulphide pulp and paper industry and sludge from the sulphide pulp and paper industry (containing lignin fiber), the best speed results were obtained growth and gain of biomass - in comparison with the control model, a 15% increase in the growth rate, 25% - biomass, which confirms its effectiveness.

The studies carried out describe a method for obtaining an organic ameliorant based on a widespread substrate of prolonged action, capable of increasing the efficiency of growth of a grass mixture, which will accelerate the process of overgrowing of the restored territory. The resulting mixture is safe to use, does not contain pathogenic microflora and weed seeds. It is characterized by the presence of traces of heavy metals in concentrations that do not lead to an accumulation above the maximum permissible concentration (MPC).

Claims (1)

A method for producing an organic ameliorant, including reagent treatment of sewage sludge with subsequent composting, characterized in that excess activated sludge from aerobic biological wastewater treatment of the sulfide pulp and paper industry is used as a wastewater sludge, a sludge of sulphide cellulose is used as a reagent. paper industry with a lignin fiber content, in a mass ratio of 3-4: 1, is dehydrated to 80%, then the substrate is mixed, and aerobic composting is carried out for at least 30 days, and then the resulting substrate is mixed with light loamy soil at a ratio by lung mass loamy soil from 70 to 80% and the resulting substrate from 30 to 20%, the resulting organic ameliorant is crushed in a hammer mill.

Images