WO2014202160A1

WO2014202160A1 - Mesh synthetic filtering filler

Info

Publication number: WO2014202160A1
Application number: PCT/EP2013/076259
Authority: WO
Inventors: Alfredo ZUFIAUR FERNANDEZ DE BETOÑO
Original assignee: Zufiaur Fernandez De Betoño Alfredo
Priority date: 2013-06-18
Filing date: 2013-12-11
Publication date: 2014-12-24
Also published as: ES2525194B1; ES2525194A1

Abstract

The mesh synthetic filler is a porous mean or supporting material used to filter a fluid, in which biomass, dissolved gases and the fluid may interact, in order to enable a purification and filtration process for all fluid types. The mesh synthetic filler has a plurality of properties ranging from size to specific surface. It can be used for all types of fluids. The fluid lines are longitudinal relative to the filter but the later has cross-sectional divisions, which barely represent an obstacle to the main fluid circulation.

Description

MESH SYNTHETIC FILTERING FILLER

Field of the invention

The present invention fails within the field of systems used to purify wastewater and gas filtering systems, namely relating to a type of biofilter with synthetic fil l ing, which is placed in the flooded biological reactors or fixed beds, to provide support for the biomass. It also serves to filter gases. The material used may be inert plastic, PP, polypropylene or a coated metal material, so that it can withstand wastewater. It must be hard to compress and manageable, given the significance of its specific surface.

Background of the invention

Wastewater filtering devices currently available are usual ly categorized according to the way in which they operate. Thus, fixed holding supports, fluidized beds, submerged bio-filters, bio-disks and bio-cylinders, can be found among the biomass reactors.

There is a large variety of supports, including fixed support fillers, perhaps of a mineral nature, the most noteworthy among them being sands and puzzolana.

Within the synthetic filler industry, models marketed under registered trademarks exist, the most common being:

Biostyrene commercialized by the firm OTU.

Biol ite commercial ized by Dcgremont.

Bionet cube elements, stacking blocks.

NORPAC elements, bulk filling.

Plasdek elements, this material forms a block stack.

Norton Acti fil elements, bulk fil ling of plastic figures.

The aforementioned devices are advantageous in that they are manufactured in equal production runs using standard sizes.

The problem with these block-stacking devices is that they are medium-volume and placed one by one.

The problems posed by bulk elements are that the reactor might get clogged and the arrangement of the synthetic materials may cause the circulation of fluids inside the reactor to become blocked. Furthermore, if the biomass develops too much it does not become loose, therefore clogging part of the fill ing and giving rise to dead points in the fluid circulation. This renders the bulk fixed bed dev ice ineffective. In conclusion, these systems are manageable for certain parameters but they are not good for high DBO concentrations. The mesh synthetic filtering filler is designed to provide a new instrument that takes the fluid circulation in vertical reactors with flooded filters, bed reactors and gas filters into account. The variety of the filler sizes available facilitates the easy handling thereof and makes it possible to install and remov e it in one single step, adjusting it to the required measurements.

All of the above leads to the design of a kind of filter with a variable specific surface, thus enabling fluids to circulate. The filter has to adapt to the dimensions of the duct where it must carry out its function.

This objective is achieved by means of the invention, as it is defined in claim 1 . In the dependent claims, other characteristics are defined.

Description of the invention

The invention relates to a type of synthetic filler device intended to be placed in submerged aerobic or anaerobic biological reactors and bacteria beds, wh ich serves to support the biomass in the wastewater purification, fluids being filtered inside the ducts of biological reactors.

The design parameters for the mesh synthetic filler needed for an aerobic or anaerobic flooded reactor and for a bacteria bed are:

A) Filtration rate (vf), organic charge being expressed in m3 of applied water per ml of biofilter surface. The filtration rate depends on the characteristics of the influent and the function of the object intended to be obtained (nitrification, de-nitrification, etc. )

B) Filler material:

The filler material has to be consistent, so it does not become deformed. Resistance to compression. It has to be wear-resistant, made of plastic materials, such as polypropylene or PP, and resistant to corrosive agents.

C) Bulk load or organic load.

This parameter provides guidance on the DQO Kg per m3 of filler material that is able to el iminate, for carbonaceous organic material, for nitrification or de- nitrification for standard parameters.

D) Sludge production.

For anaerobic processes with flooded filter, it is estimated that sludge reduction constitutes approximately 70 % of the volatile solids and for aerobic processes with flooded filter, a 50% sludge reduction will occur relative to volatile solids.

E) Gas introduction.

The introduction of oxygen and gases depends on the biological process being carried out; the arrangement of the synthetic mesh filter framework has been studied so the lines of the liquid fluids and the gases are longitudinal throughout the entire the volume.

F) Depth.

This factor is important so that the filter does not become deformed. The aim is to provide a highly porous dev ice that is resistant to compression and is financially viable.

The mesh filter object of the present invention is unique in that when it is folded over its axis, it forms a flat surface on the vertical axis and after turning it several times in this manner, it forms a mesh formed by squares. When it rotates around its axis, a mesh forms a three-dimensional amour, i.e. a hollow rigid volume of a porous material. The mesh may be wound in a circular, ovular or square manner and most commonly in an Archimedes spiral.

The part formed by spinning a mesh around its axis is cyl indrical in shape; in a plan view, it draws an Archimedes spiral, the dimensions of which depend on the number of turns and the distance separating two adjoining faces. The specific surface of the filler is determined by the pores or gaps remaining in the volume, i.e., when the separation between faces is smal l, the density is high.

In another aspect of the invention, the size of the mesh, formed by a network of squares is significant. The material may be metal but plastic makes the synthetic filter unique given that it is resistant to alkaline systems. A high or low specific surface is obtained depending on the mesh size. The filter is not standard because it depends upon the winding, i.e., the total number of turns around its axis needed in order to obtain the desired volume.

The part is formed starting from the center of a hollow plastic tube, which provides consistency and manageability when the time comes to transport and position it in average filtration systems.

Brief description of the drawings

Next, a series of drawings, provided for a better understanding of the invention, are briefly described.

1.- The net synthetic filler starts with a mesh net, preferably made of squares, although it may be constructed by any parallelepiped figure, squares being the most even distribution of the two-dimensional plane.

2. -When a net is wound around its axis it forms a cylinder, this sol id cyl inder being porous, since it is formed by a net in which there are free areas in the three- dimensional space. The mesh net, the dimension of the squares and the thickness of the plastic is related to the desired volume.

As far as winding is concerned, the number of turns is defined by the inner radius, the outer radius and the distance between faces.

3.- Plan view, with a central hole of a PVC tube, forming an Archimedes spiral.

4.- Elevation view of the mesh filter.

Development of the invention

The mesh synthetic filtering filler, is synthetic filler intended to be placed in reactors with cyl indrical or parallelepiped ducts of bacteria beds, submerged biological reactors, or gas filters, in such a way that the flow lines are directed so as not to hinder the fluid flow. The mesh filter is adapted to the reactor duct, whether it is large or small in size.

The characteristic of this synthetic filler is that it is not of the standard model variety, since the manufacture of each filler type is individual and adapted to parameters such as the reactor diameter and density. These parameters vary according to the characteristics of each fluid type.

When the fluids cross the space, they are subject to the laws of physics and when they circulate through a framework of nets, they bump into them, thus being diverted, and undergoing turbulences. How ever, if the fluid passage goes in a straight direction, they fol low that direction.

Some data is needed in order to size the structure of a net filter, namely:

1) Calculating the volume needed.

The volume needed is calculated based on the recommended fluid flow rate values.

Bearing in mind that retention times in mesh filters are shorter than in active sludge processes, organic charges will depend on the water concentration, temperature, on the filtration process selected, the support and the biological process (nitrification, de-nitrification, etc. ).

2 ) Determining the surface needed for the filtration rate.

The way in which the system operates must be taken into account, by means of nitrification, de-nitri fication and calculating the recirculation flow rate.

The surface will then be calculated taking into account the design flow rate and the filtration rate.

3 ) Height of the mesh filter.

After having studied the compression resistance the mesh filter is capable of withstanding, it is recommended that this be as high as possible.

4) Calculat ion of the oxygen needed.

For aerobic biological processes such as carbonaceous removal, nitrification and de-nitrification, it is necessary to size the system.

The characteristics of the mesh synthetic filter made of PP are:

Thickness of the mesh wall 2 mm

Filter type FR 1 m3

Cylinder dimension : r = 0.564. H = 1 m

Specific surface m2/m3 7 m2/m3

Weight Kg/m3 30.4 Kg/m3

Porosity, gaps 95%

Resistance to compression 200 Kg

Claims

1.- The mesh synthetic filtering filler is a three-dimensional framework of regular figures, characterized in that, it is formed by winding a mesh of two- dimensional geometric figures, i.e. a parallelepiped, around an axis. The most regular figure is the mesh formed by square figures. The figure formed on the plane is an Archimedes spiral . In the center of the mesh filter, there is a PVC cylinder with a handle. The PVC cylinder makes the entire volume rigid.

2.- The mesh synthetic filler according to claim I characterized in that the volume of the formed mesh filter ranges from cubic centimeters, to sev eral cubic meters, depending on the number of times the mesh is wound around its axis and the distance between the adjacent faces of the mesh.

3.- The mesh synthetic fil ler according to claims 1 and 2 characterized in that the specific surface, the porosity degree of the mesh synthetic filler, ranges from very high v alues to median values, owing to the distance of the two adjacent faces of the mesh forming the filter and the size of the mesh pattern.

4.- The mesh synthetic fil ler according to claims 1 ,2 and 3 characterized in that the resistance to compression of the mesh filter is high due to the material used, be it a synthetic plastic PP material, high density polypropylene or metal mesh coated w ith a protector.

5.- The mesh synthetic filler according to claims 1 , 2, 3 and 4 characterized in that the filter can be easily handled, each synthetic filler piece having an anchor inside the tube that forms the mesh fil ler. This anchor serves to hold the filter with an elevator.