CZ2005217A3 - Sludge of wastewater treatment plants - Google Patents

Abstract

BACKGROUND OF THE INVENTION The present invention relates to a sludge from a sewage treatment plant comprising the addition of bone and / or meat-and-bone flour, and optionally the addition of a biologically-enzymatic preparation with bound microorganisms. Other admixture is mineral or live material, based on crushed mineral or organic matter. The content by weight of the biologically-enzymatic preparation with bound microorganisms is in the range of 0.02 per mille and 5 per cent of laboratory sludge dry matter. The content of bone or meat-and-bone meal is, depending on the mechanical properties and end-use requirements, in the range of 0.001 to 95 percent by weight of sludge. For recultivation purposes, the sludge further contains fly ash from combustion coal and calcium-based solid reaction products from flue gas desulphurisation. For soil, land and horticultural soil recovery, sludge contains plant tissue waste, animal manure and manure, including polluted straw and farm organic products, or forestry waste.

Description

Technical field

The present invention relates to sewage sludge.

The prior art

Sludges from waste water treatment plants are used as materials for land reclamation and for agro-forestry use.

For this purpose, it is added to the sludge according to the end-use, for example, thermal fly ash, thermal desulphurisation products and organic material of animal or plant origin.

This material is then transported the territory devalued by previous use. The disadvantage of using these materials is the release of forms of nitrogen, nutrients, heavy metals and their chemical forms, which cause undesirable contamination of soil and consequently also of water.

Another disadvantage after depositing such a material is also the possible occurrence of greenhouse effect gases, which is due to the imperfect decomposition of organic matter, such as methane and carbon dioxide.

So far known sludge and technological mixtures from sludge do not always have the necessary total content and proportional representation of nutrients due to their expected area of use for land reclamation and for agro-forestry use.

Some sludges, especially from smaller wastewater treatment plants, are produced with a low dry matter content (up to 10%), which makes their subsequent use difficult.

It is therefore an object of the present invention to provide a material that is physically and biologically stable, has good handling through higher dry matter, substantially reduces the production of environmental contaminants, and contains a sufficient amount of nutrients in a suitable ratio for use in agriculture, forestry and reclamation.

SUMMARY OF THE INVENTION

The essence of the wastewater treatment plant sludge according to the invention consists in the addition of bone and / or meat and bone meal and a variant addition of a bio-enzymatic preparation with bound saprophytic microorganisms.

Optionally, the base material comprises an admixture of a mineral or nutrient material based on crushed mineral or organic matter.

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The content of bone or meat-and-bone meal is, depending on the requirement for mechanical properties and the ultimate technological use, in the range of 0.001 to 95% by weight of the waste water treatment sludge.

The variant addition of the biologically-enzymatic preparation with bound microorganisms is in the range of 0.02 per mille to 5 percent by weight, based on the laboratory dry weight of the base material.

Preferably, the material comprises coal fly ash and solid calcium based reaction products from flue gas desulfurization.

For use in agriculture, forestry and horticulture, the material includes plant tissue wastes, animal droppings and manure, including contaminated straw and farm organic products, or forestry wastes.

An advantage of the sludge according to the invention is to increase the content of biogenic nutrients, in particular Ca, P in the final organic or organomineral mixture, whilst reducing the content of hazardous elements and harmful substances due to the naturally low content of these undesirable substances in bone or meat and bone meal.

Other advantages are the improvement of mechanical properties, ie the ability to be layered and manipulable with the resulting material - an important aspect especially in the production of aqueous sludge COV, in radical reduction of the technological process of production of the final product (instead of 60 to 100 days of classical composting to 10 to 30 days) and reducing the necessary handling space and increasing the production capacity of the equipment, reducing the funds for overburdening, irrigation and temperature monitoring in the compost pile (according to the methodology contained in ČSN- 465735 Industrial composts); (formation of gases, waste - fly ash, energy intensity, etc.), in reducing the financial investment costs for the acquisition and maintenance of waste recovery facilities, in the possibility of easy and controlled increase of dry matter of the final product material and in the possibility of continuous mixing regardless of adverse climatic conditions of the season.

DETAILED DESCRIPTION OF THE INVENTION

A biological-enzymatic preparation with bound microorganisms is optionally added to the sewage sludge. When using sludge alone, the weight content of the biologically-enzymatic preparation with bound microorganisms in the sludge is in the range of 0.1 per mille to 1 percent to the dry matter of the sludge. The biologically enzymatic preparation is particularly represented by saprophyte microbiological strains decomposing the organic matter from aerobic or anaerobic conditions, optionally bound to a suitable mineral protective medium.

If the bio-enzymatic preparation with bound microorganisms is mixed with another admixture, eg with mineral or nutrient material, before being added to the sludge, on the basis of crushed mineral. or organic matter, the content of the final biological-enzymatic preparation with bound microorganisms in the sludge is proportionally increased by the added admixture. The content of this bioproduct in the sludge is then in the optimally effective range of 0.1 to 5 percent.

The content of bone or meat-and-bone meal in the sludge is dependent on the requirement for mechanical properties and the end use in the range where its content from 5 to 50% is suitable for reclamation and combined use in agriculture where it can be applied by spreading into the soil.

A higher content of bone or meat-and-bone meal from 50 to 95%, which forms a denser mixture, is suitable for direct agriculture where the sludge is applied by spreading and plowing into the soil.

The upper limit of the addition of bone or meat-and-bone meal must be used for aqueous sludge of WWTP, where it is necessary to achieve the necessary manipulability and physical properties of the mass.

When sludge is used for land reclamation, the sludge contains coal ashes as a further admixture and solid calcium-based reaction products from flue gas desulfurization

When sludge is used as a fertilizer in agriculture, forestry and horticulture, the other admixture of sludge is waste from plant tissues, animal droppings and manure, including contaminated straw and farm organic products, or forestry waste.

Claims (6)

PATENT CLAIMS Sewage sludge, characterized in that it comprises the addition of a biologically-enzymatic preparation with bound microorganisms and the addition of bone and / or meat-and-bone meal. 2. Sewage sludge according to claim 1, characterized in that it contains a mineral or nutrient material based on crushed mineral or organic matter 3. Sewage sludge according to any one of the preceding claims, characterized in that the weight content of the biologically-enzymatic preparation with bound microorganisms is in the range of 0.02 per mille to 5 per cent of the laboratory sludge dry weight. 4. Sewage sludge according to one of the preceding claims, characterized in that the content of bone or meat-and-bone meal is between 0.001 and 95% by weight of the sewage sludge, depending on the requirement for mechanical properties and the end use. 5. Sewage sludge according to claims 1 to 3, characterized in that it contains coal combustion fly ash and solid calcium-based reaction products from flue gas desulfurization 6. Sewage sludge according to claims 1 to 3, characterized in that it contains plant tissue waste, animal droppings and manure, including contaminated straw and farm organic products, or forestry waste.