TECHNICAL AREA

The invention relates to a multi-layered cascade biofilm-based biological wastewater treatment system, which includes a new approach in the biological treatment of wastewater, which was not encountered in previous studies.

PRIOR ART

Waste water treatment is the process of making the polluted water dischargeable after being used for domestic or industrial purposes. This treatment process can be achieved physically, chemically or biologically. Biofilm systems formed by the attached growth of microorganisms on a media are well known in the biological treatment of wastewater. These systems are especially used in treatment plants such as trickling filters and rotating biological discs.

Biofilm formation is a process that consists of a series of steps. It begins with the adsorption of macromolecules (e.g. proteins, polysaccharides, nucleic acids and humic acids) and smaller molecules (e.g. fatty acids, lipids and pollutants such as polyaromatic hydrocarbons and polychlorinated biphenyls) onto surfaces. These adsorbed molecules act as a concentrated source of nutrients for microorganisms and aid in forming films that can have many effects on the physicochemical properties of the surface. On the other hand, these molecules enable to suppress or increase the release of toxic metal ions from the surface, detoxify the solution through the adsorption of inhibitory substances, provide essential nutrients and trace elements for a biofilm, and trigger biofilm formation. After the surface is conditioned, the cells begin to attach (adhere) to the surface. The adhesion of bacteria to a surface is followed by the production of extracellular polymeric substances (exopolysaccharides=EPS). They are predominantly made of polysaccharides and proteins. EPS help form mature biofilms by forming a slimy substance called a biofilm matrix. Figure 1 shows the steps in the formation of mature biofilms (Lewandowski and Boltz, 2011 ).

When a mature biofilm is formed on a surface, it actively spreads and eventually covers the entire surface. The diffusion mechanisms in mature biofilms are more complex than those in the initial surface attachment state. Many of these biofilm spreading mechanisms are illustrated in Figure 2. In mature biofilms, microorganisms are embedded in the extracellular (extracellular) layer of polymeric materials (EPM). Figure 3 shows the image of a mature biofilm obtained using scanning electron microscopy (SEM). Although the EPM in this image is reduced to a mixed network of dry filaments after drying for visualizing via electron microscopy, microorganisms embedded in an EPM matrix attached to a surface are still visible (Lewandowski and Boltz, 2011 ).

When the process in a biofilm system is stimulated, the biofilm system becomes a biofilm reactor. Biofilm systems consist of four partitions:

• The surface to which microorganisms attach (adhere)

• Biofilm (microorganisms and matrix)

• Solution of nutrients and

• Gas phase (if applicable).

Biofilm reactors (Figure 4) used for wastewater treatment in prior studies are generally designed and operated to optimize biofilm activity. Conventional biological systems that treat wastewater generally require the accumulation of active microorganisms in a bioreactor and the separation of microorganisms from the treated wastewater. Especially in reactors containing suspended growth organisms, such as the activated sludge process, microorganisms grow and become biological flocs. The flocs obtained are freely suspended in the liquid phase. The flocculated bacteria are then separated from the liquid by settling tanks or membranes. Sedimentation dependent suspended growth reactors are dependent on recycled activated sludge from the settling tank to provide the desired active biomass concentration in the activated sludge bioreactor. Biofilm reactors keep bacterial cells in a biofilm attached to fixed or freely moving carriers. The biofilm matrix consists of various soluble and particulate components including water and soluble microbial products, biochemical reaction waste material, and EPS with soluble and particulate content.

Unit Operations in the Treatment of Domestic Wastewater

The following unit operations are generally used in all systems in the biological treatment of domestic wastewater:

First Stage (Primary) Treatment:

Primary treatment processes for wastewater treatment are designed to meet the following conditions (TS EN 12255-3, DIN EN 12255-3): • Providing suitable conditions for effective and efficient operation of waste water treatment units,

• Reducing the hydraulic retention time required in the facility,

• Ensuring efficient operation of sludge processing units thanks to fine screen and sieve systems, separation of inert materials entering the facility with screen chamber,

• Providing the necessary conditions for the safe operation of treatment processes,

• Ensuring the protection of equipment.

The first stage treatment units in urban wastewater treatment plants are summarized below.

Screens

With the establishment of screen systems, it is ensured that solid and coarse materials are removed from wastewater. Coarse screens must be installed before pumping stations. Fine screens, on the other hand, are installed in order to remove the floating materials that remain in the wastewater after the coarse screens and that damage the mechanical equipment in the following units, thus reducing the possible blockages in the sludge treatment units (Koyuncu, 2013).

Screen Types and Number of Units

Screens are divided into coarse and fine screens in terms of screen opening. Coarse screens, pump impellers wear, clogging, etc. It is placed at the entrance of the promotion centers in order to protect against the effects of the effects. The bar spacing of coarse screens can be 30~50 mm. At the entrance of the waste water treatment plant, the collector flow elevations can be very deep (5.0 - 10.0 m). Therefore, coarse screens installed at the plant entrance can also be placed quite deeper down the ground surface. Since the length of such deep screens will be long, it may take 2 to 3 m inutes for the rake to descend to the level of the water flow from the host place above the water level and to come back to the first position above the water level. Meanwhile, the average speed could be 0.15 - 0.20 m/sec.

It is possible to clean coarse screens manually or automatically. It is used to reduce the load of structures such as fine screens, grit chambers, and pre-settlement tanks. Bar spacing can be 10~30 mm in fine screens. Fine screens are generally mechanically cleaned and the rake scraping speed can be 0.10-0.15 m/sec. It takes between 2 and 5 minutes for the rake to make one revolution (working cycle) depending on the screen size. Screens are classified as follows in terms of working principle: Fixed bar screens: These are usually equipped with mechanical equipment. Rotary screens: These are usually cleaned with pressurized water.

Grinders: These do not need to be cleaned as they grind the waste they hold and mix them back into the water.

Pump Stations

Wastewater pumping stations are established to meet the needs such as elevating and transferring the wastewater from one place to another within the wastewater treatment plant or the sewage system.

Grit chambers and oil separators

The grit chamber is an important process component for reducing the problems caused by sand and oils in wastewater. Small particles such as sand cannot be biodegraded and also damage mechanical equipment such as pumps. Sand accumulates in channels, sedimentation tanks, sludge digestion, and sludge dewatering units and create serious operational problems. Oil, on the other hand, creates a problem especially in sedimentation and is stripped from the final clarifier surface (MWA, 1998; Koyuncu, 2013). In grit chambers, the flow rate is reduced to settle large particles and the sand is then taken from the channel bottom. Oil and grease are taken off from the surface. Combined sewer systems contain significant amounts of sand entering the system from roads, pedestrian pavements, and floodplains. Separate sewer systems, on the other hand, contain sand, especially in the coastal or sandy areas. Because of its harmful effects, grease must be removed before it begins to dissolve or disperse. Where there is domestic and urban wastewater, including discharges from hotels, restaurants and food processing plants, a grease and oil removal unit should be included in the design of treatment plants. As an alternative to grease removal, it may be possible to combine sand and grease/oil retention in a single unit or as a separation stage in the primary settling tank. Grease and oil removed from wastewater must be disposed of in accordance with the health and safety requirements specified in DIN EN 12255. The design of the grease separator should be such that it facilitates the safe and effective removal of separable solids, grease, and oil (Koyuncu, 2013).

Flow Measurement

Routine measurement of wastewater flow rate in wastewater treatment plants is essential for a healthy design and operation control of the plant. The benefits of knowing the average and daily flow rate changes can be summarized as follows: • Determining the daily amount of chemical substance to be added to the system • Determining the amount of air to be supplied to the system

• Determination of sludge return rate

• Establishment of current flow records when it comes to enlarging the facility

• Significant flow increases determined in daily dry weather conditions; Obtaining information about leakage or discharge of industrial wastewater into the sewer system and population growth

• Estimation of rainwater contribution based on significant flow rate increase in rainy weather conditions.

Flow Equalization

Stabilization ponds are used to compensate for large changes in flow and pollution load reducing the hydraulic load in the primary settling pond. Flow balancing unit is not used in cases where there are long aerated activated sludge systems with a holding time of more than 18 hours and settling basins sized according to the peak flow rate. In the equalization tank, mixing is applied to stabilize the concentration and prevent precipitation. Partial oxidation of biodegradable substances and BOD also takes place with mixing and aeration. Mixing methods in equalization tanks are as follows; distribution and screening of inlet flow, mixing with turbine mixers, aeration with diffusers, aeration with mechanical aerators. Flows exceeding the design capacity of the later stages should be diverted into the flow balancing tank. This should be after the screening and grit removal processes. It is not a unit used in all treatment plants. It is used when needed.

Primary Sedimentation

Primary sedimentation is the separation of most settleable solids. With the removal of solids from raw wastewater, suspended solids and BODs are also removed at certain rates. By removing the foam in the raw wastewater, foam formation in the aeration and final settling tanks is reduced. Another important task of primary sedimentation tank is balancing the raw wastewater concentration and changes in flow rate. Primary sedimentation tanks are installed in large capacity wastewater treatment plants (>3800 m ³ /day). In smaller facilities, the capacity of the second-stage treatment units should be sufficient and, in cases where there are no operational problems caused by floating residues such as foam, oil, etc., there is no need for a primary sedimentation unit. Primary sedimentation must be located before second-stage treatment systems such as trickling filter, rotating biodiscs, and submerged biofiltera. In a well-designed and properly operated pre-settlement unit, 30-35% BOD5 and 50-60% suspended solids are removed from typical domestic wastewater. In urban wastewater, where the contribution of industrial wastewater reaches significant levels, these ratios change due to the difference in the amount of dissolved BOD5 in the wastewater. When chemicals are added to the pre-settlement tank, the treatment efficiency increases significantly. BOD5 and SS removal rates may fall below typical values due to extreme situations such as hydraulic short circuits in the settling tank, excessive fluctuations in wastewater flow, very high or low wastewater temperatures, and high recycle rates.

The waste water flow that will enter a treatment plant with a well-planned first-stage treatment stage should be balanced and the following treatment units should be designed in such a way that they will not be adversely affected by flow fluctuations (TS EN 12255-3; Koyuncu, 2013).

SECONDARY TREATMENT (BIOLOGICAL TREATMENT)

The treatment plant components up to this point are generally first-stage structures that can be found in every biological treatment plant. As the second stage treatment, any of the systems such as activated sludge systems, lagoons and systems containing biofilm formation, which is the subject of the invention in this research, such as biodiscs, trickling filters can be used. Biofilm systems can sometimes be used as advanced treatment after activated sludge systems.

Biofilm Treatment Systems

Biofilm systems are systems based on the principle that microorganisms develop as a film layer on a suitable support medium and that purification is achieved by contacting wastewater. Trickling Filters (TF) and Rotating Biodiscs (RBD) operated are the most widely used biofilm systems. The most important advantages of biofilm systems are given below:

• Their operation is generally easy and stable.

• Activated sludge recycling is not required.

• The trickling filter and biodisc systems allow microorganisms with long growth times to form colonies. Therefore, at low loads, it is possible to remove compounds that are difficult to decompose.

• Energy requirements are generally low (WEF, 2011 ).

Standard technical rules for the design of carbon removal, nitrification, and denitrification in trickling filters and carbon removal and nitrification in Rotating Biodiscs are given below. These principles can be applied to wastewater generated as a result of activities that serve domestic, commercial, or agricultural waste water over 50 equivalent population (Koyuncu, 2013).

Trickling Filters

Trickling Filters are fixed bed biofilm reactors. Waste water is fed to the trickling filter by the distribution system over the filter media. While the water filtered from the surface of the biofilm flows downward, the air moves up or down and passes into the fluid and the biofilm by diffusion. The components of the trickling filter system are the inlet waste water distribution system, generally circular tank with stone or plastic filling material, the permeate collection (bottom drainage) structure, and the ventilation system (WEF, 2011 ).

In order for wastewater to be treated in biofilm systems, it must have undergone at least one of the following processes:

• Primary sedimentation

• Screening and/or sieves

• Secondary treatment (It may not be necessary depending on the characteristics of the waste water, in this case the biofilm system itself will be the secondary treatment) Biofilters can be operated aerobically or anaerobically. In order for them to be operated aerobically, the following conditions must be met.

• Providing suitable conditions for the bacteria to adhere to the filter material or the material on which it will multiply on the surface,

• Effectively contacting the wastewater with the biomass growing on the surface,

• Controlling excessive biofilm growth to avoid clogging,

• Although the oxygen requirement is met naturally from the air around the biofilm, additional oxygen can be supplied to the waste water by means of a blower from outside in case of need.

Wastewaters that can be treated with aerobic biological processes growing in suspension can also be treated with trickling filters and Rotating Biodiscs. The properties that should be on the support media surface used in biofilm systems are listed below.

• The support material must show sufficient resistance against external mechanical effects.

• It should be resistant to weather conditions and UV rays.

• It should be resistant to chemical compounds in the wastewater.

• It should not be biodegradable. • Appropriate materials should be selected so that the biofilm can adhere to the surface.

• The hollow structures (micropores) in the biofilm material should be protected.

• For the plastic filling material, the manufacturer's information must be checked before the application.

The following aspects should be considered when planning biofilm systems:

• Characteristics of the feed wastewater,

• Dimensions and capacity of the biological reactor,

• Effects of unwanted accumulation in tanks and channels and prevention of dead zones,

• Establishing multiple lines/units or other technical measures to ensure that the required final effluent quality is maintained if one or more lines/units fail,

• Surface area, volume and depth of the final settling tanks when a probe is used,

• Treatment of the produced sludge and its delivery to the final point,

• Minimizing hydraulic losses,

• Measurement and control system,

• Environment features (Koyuncu, 2013).

Rotating Biological Discs (Rotating Biodiscs)

• General introduction and purpose of Rotating Biodiscs

• In rotating biodiscs, wastewater treatment is carried out with biomass attached to the disc surface. The biodiscs are operated by being partially immersed in the wastewater coming into the trough-shaped structure and slowly rotated. During this rotation, the biomass on the biodisc is alternately contacted with air and wastewater (WEF, 2011 ).

General requirements

• The general requirements for trickling filters also apply to rotating biodiscs. In addition, the following conditions must also be satisfied:

• After the discs are brought into contact with the wastewater, they must also come into contact with the air above the water level.

• Sufficient oxygen must be provided in order to keep the biofilm in the tank under aerobic conditions during contact with air when the biodiscs are submerged. In order to provide these conditions, the required minimum rotation speed must be maintained in the biodiscs.

• At least 40% of the disc surfaces must be out of the water in order to provide sufficient oxygen during the rotation and to prevent oxygen restriction for nitrification. • Floc formation similar to the activated sludge system can be observed in the wastewater inside the tank. However, such microbial formation is not taken into account in sizing as it will affect the treatment performance to a small extent.

• In the tank structure, sufficient turbulence should be provided to prevent sludge from settling by selecting the biodiscs and/or the rotation speed of the biodisc appropriately.

• Biodiscs should be covered against possible icing in winter. In the closed state, metabolic products in gaseous form accumulate in the top space of the system. In order to prevent the accumulation of gaseous products, it is necessary to provide sufficient oxygen and ensure that it is adequately absorbed by the biodisc.

• The best efficiency is achieved with compact biodisc manufacturing.

• In the system, it is necessary to safely remove excess sludge from the structure, provide oxygen transfer to the biofilm, and minimize energy consumption.

Types Rotating Biodiscs and Number of Units

• Rotating Biodiscs can be designed as disc or cylindrical structure depending on the biofilm surface. Since there will be limited biofilm surface area in a single unit produced modularly by the manufacturer, it is necessary to use a large number of units in a series-connected cascade structure. For carbon removal, at least 2 units in series are required while, for nitrification, at least 4 units in series are recommended. Depending on the discharge criteria, the number of cascades can be increased.

Secondary Sedimentation Tanks

• Final settling tanks (secondary sedimentation tanks) in biofilm systems require less hydraulic retention time than activated sludge.

• A smooth and symmetrical distribution of the flow must be ensured at the entrance of the facility.

• It should be ensured that the water is drawn symmetrically and slowly in the outlet structure, the materials accumulated on the surface are easily collected, and the sludge is prevented from being carried to the weirs.

• Sludge collection and removal should be planned according to the type and size of the final settling tanks. • In places where sludge chambers are built, the angle (inclination angle) of the edges of the chamber with the horizontal should not be less than 60° for pyramid-shaped chambers and 50° for conical chambers.

• For small units, sludge should be collected by gravity on very steep surfaces (such as 50°-60°) and as smooth as possible.

• In plants with biological nitrogen removal, excessive retention of sludge in the final settling tank should be prevented.

• In the final settling tanks, the hydraulic retention time is less than 1 hour.

Final settling basins can be designed in such a way that sludge is discharged from the center or from the side according to the pond geometry. As additional information, more than one settling tank should be planned for activated sludge systems with a wastewater treatment capacity of more than 400 m ³ /day.

When one of the tanks fails, the other tank(s) must be capable of handling the maximum hourly flow. For systems with only one settling tank, it is mandatory to specify the measures to ensure continuous treatment. In case the inner diameter of the final settling tank exceeds 50 m, measures should be taken to minimize the effect of the wind. The water depth at the edge should be at least 3.7 m for suspended growth systems. For systems that grow on the surface, the edge water depth will be at least 3.0 m. As for the solid loading rate, the maximum hourly flow should be taken into account for waste water flowrate (Q) and return sludge flowrate (QRAS). Secondary sedimentation tank air gap should be at least 0.3 m. The upper level of the side wall must be at least 15 cm above the ground level. If the sludge is to be collected from the final settling tank with the scraper system, the base slope towards the sludge chamber should be planned as 1 -15 (Vertical-Horizontal).

Sludge Stabilization (Sludge Digestion)

In short, the stabilization of the sludge is the process of bringing the sludge to a stable state that can be disposed of without causing any harm to the environment and without creating a bad smell. Waste sludge is stabilized to remove pathogens, prevent odors, reduce, inhibit or stop potential degradation. The success of achieving these is related to the effect of the stabilization process on the volatile or organic part of the sludge. While designing the stabilization process, the compatibility of the stabilization process with other treatment units is important. For sludge stabilization;

Lime stabilization

Heat treatment • Anaerobic digestion

• Aerobic digestion

• Composting methods are used (Koyuncu, 2013).

BRIEF DESCRIPTION OF THE INVENTION

The "VERTICAL CASCADE BIOFILM WASTEWATER TREATMENT SYSTEM" (VCB), which is the subject of our invention, is a treatment plant type that has not been encountered in previous studies using biofilm. Although various forms of biological treatment systems containing biofilm have been encountered (Figure 4-6), a similar system has not been found with the advantages brought by the arrangement in the form of low slope terraces one after the other in this study (prevention of dead spots, absence of low oxygen sections, nitrogen and phosphorus removal compared to classical biofilm systems as well as a biofilm scraper (Figure 7-10) providing greater control, ease of operation, and no clogging. VCB includes the first-stage treatment units described above and can also be used as a second-stage treatment unit or as an advanced treatment unit.

In previous studies, general flow charts and contents of classical biofilm systems (CBS) were given. As explained on pages 4-11 , the basic units that should be in the CBS, their general needs, and their status in this invention (VCB) are listed below: Screens

Pumping Station

Grit/Oil Removal Chamber

Flow Equalization

Primary Sedimentation

SECOND STAGE TREATMENT (BIOLOGICAL TREATMENT) (Biofilm Treatment Systems = Trickling Filters or Rotating Biological Discs)

Secondary Sedimentation

Sludge Stabilization (Sludge Digestion)

Looking at the order above, it is seen that the difference is in the type of biological treatment. If CBS is selected for biological treatment, the following conditions must be met in trickling filters: • Effective contact of wastewater with biomass growing on the surface

• Controlling excessive biofilm growth to avoid clogging

• Although the oxygen requirement is met naturally from the air around the biofilm, additional oxygen can be supplied to the waste water by means of a blower in case of need.

• Dimensions and capacity of the biological reactor

• Prevention of harmful accumulation in tanks and channels and of dead zones

• Establishing multiple lines/units or other technical measures to ensure that the required final effluent quality is maintained if one or more lines/units fail

• Measurement and control system

The following requirements must be met for Rotating Biodiscs:

• After the discs come into contact with waste water, it must contact with air above the water level.

• Enough oxygen should be provided to keep the biofilm submerged in wastewater and in aerobic conditions during contact with air. In order to provide these conditions, the required minimum rotation speed must be maintained for the biodiscs.

• At least 40% of the disc surfaces should be out of the water in order to provide sufficient oxygen during the rotation and to prevent oxygen restriction for nitrification.

• In the tank, sufficient turbulence should be provided to prevent sludge from settling by selecting the biodiscs and/or the rotation speed of the biodisc appropriately,

• Sufficient oxygen transfer to the biofilm must be ensured and energy consumption should be minimized.

• Rrotating biodiscs should be at least in 2 series of connected units for carbon removal while at least 4 series of connected units are recommended for nitrification. Depending on the discharge criteria, the number of discs can be increased.

In this invention (VCB):

• Since the waste water will flow slowly on the inclined plates, its contact with the biomass is guaranteed.

• It is a system with the lowest probability of clogging among attached growth waste water treatment systems since inclined plates with large gaps between are used as well as a sludge scraper. • Since large surface area provided by inclined plates will keep contact with atmosphere at the highest level, there is no need to use an additional blower or to install additional ventilation systems.

• In order to meet the discharge standards according to the character of the waste water, the number of plates can be increased vertically as desired or a second tier of vertical cascade system can be activated to limit the height of the treatment plant.

• Dead zones will not occur on inclined plates as wastewater flows slowly over a wide area.

• Deactivation of the plates will not occur in the system.

• This system is easy to measure and control.

• Conditions such as providing the appropriate disc rotation speed, providing contact with air will not be seen in VCB unlike Biodiscs.

• There is no turbulence to prevent sludge precipitation.

• Unlike other biofilm systems, since it contains a sludge scraping mechanism, there is no sludge accumulation or problems arising from it.

LIST OF FIGURES

Figure 1. Stages in biofilm formation (I) Biofilm formation (II) Adhesion (III) Colonization (IV) Growth (Mass increase) (V) Fluid flow (VI) Surface (modified from Lewandowski and Boltz, (201 1 ))

Figure 2. Biofilm propagation mechanisms (VII) Flow (VIII) Split (IX) Distribution of inoculating organisms (X) Ripple (XI) Rolling (modified from Lewandowski and Boltz, (2011 ))

Figure 3. SEM image of Desulfovibrio desulfuricans bacteria embedded in EPM in a biofilm layer (Lewandowski and Boltz, (2011 )

Figure 4. Biofilm reactor types used in prior studies (a) Trickling filter b) Upstream submerged fixed bed biofilm reactor c) Downstream submerged fixed bed biofilm reactor d) Rotating biological disc e) Suspended biofilm reactor including air supply f) Fluidized bed reactor g) Moving bed biofilm reactor h) Membrane biofilm reactors.

Figure 5. General structure of trickling filters (section). (XII) Rotary distributor (XIII) Distributor arm (XIV) Tank structure (XV) Fill material (XVI) Base screen system (XVII) Filtration collection (XVIII) Air distribution duct (XIX) Outlet (XX) Inlet (adapted from Koyuncu, 2013) Figure 6. Rotary biodisc components (Cross-section) (XXI) Inlet (XXII) Oxygen (XXIII) Organic biofilm (XXIV) Cover (XXV) Disc (XXVI) Curtain (XXVII) Biodegradable products (XXVIII) Organic biofilm (XXIX) Nutrients (XXX) Released (modified from Koyuncu, 2013)

Figure 7. Cross-sectional view of the biofilm treatment plant that is the subject of the invention

Figure 8. Three-dimensional view of the biofilm treatment plant that is the subject of the invention (without scraper)

Figure 9. Three-dimensional view of the biofilm treatment plant that is the subject of the invention (with scraper)

Figure 10. Detailed 3D of the biofilm treatment plant that is the subject of the invention

The corresponding numbers in the figures are as follows;

1 . Plates with a rough surface on which biofilm will form

2. The motor that drives the sludge scraper

3. Channelled rail system in which the motor that drives the sludge scraper advance

4. Sludge scraper blade

5. Main pipes carrying the wastewater to the treatment plant

6. The gap that allows the scraper to pass to the bottom plate at the junction of the plates

7. Inlet water pipes that drain the inlet waste water onto the plates (distributor)

8. Detailed section (A) showing the positions of the scraper blade and motor and their return to the bottom plate (Figure 10)

9. Steel pipes that keep the plates fixed in the zig-zag position, ensure that the plates receive support from each other, and the number 3 rail system is fixed

10. Settlement tanks where the sludge and the treated water are separated

11 . Outlet pipes for the removal of the settled waste sludge

12. Large holes on the plates that allow the passage of water flowing to a lower plate

13. The direction in which the scraper moves and the flow direction of the waste water

14. Treated water discharge pipe

15. Ball wheel attached to the scraper motor shaft DETAILED DESCRIPTION OF THE INVENTION

The invention consists of parts and sections such as plates with a rough surface where the biofilm will form (1 ), the motor (2) that allows the sludge scraper to advance, the channeled rail system (3) where the motor moves the sludge scraper, the sludge scraper blade (4), the main pipes that carry the waste water to the treatment plant (5 ), the gap (6) that allows the scraper to pass to the bottom plate at the junction of the plates, the inlet water pipes that drain the inlet waste water onto the plates (distributor) (7), the section showing the position of the scraper blade and the motor in detail, which explains its return to the bottom plate (8)(A), steel pipes that keep the plates fixed in the zig zag position, ensure that the plates receive support from each other and fix the rail system (9), settling tanks where the sludge and the treated water are separated (10), outlet pipes that provide the removal of the settled waste sludge (11 ), wide holes that allow the passage of water flowing on the plates to a lower plate (12), the direction in which the scraper moves and the flow direction of the waste water (13), treated water discharge pipe (14) and ball wheel (15) connected to the scraper motor shaft.

In the invention, it is possible to increase or decrease the number of layers according to the wastewater character (weak, medium, strong). The VCB seen in Figures 7-10 is applied as two tiers for dividing the flow rate of high strength wastewater, reducing and adjusting the hydraulic load and organic matter load. The material of the plates (1 ) with a rough surface, on which the biofilm to be established in the system will form, is not metal, but is formed by using at least one of hard plastic, thin concrete or fiber material. Since a large part of the surface will be covered with biofilm, direct exposure to sunlight will be minimal. Since the surfaces of the plates (1 ) on which the biofilm will form will be in 100% contact with the atmosphere, a fully aerobic zone will be formed in the surface parts of the biofilm, a partial anaerobic and partial aerobic zone in the middle parts, and a fully anaerobic zone at the bottom. Since there will be no lack of oxygen on the surface, all aerobic processes will take place (C oxidation, nitrification, advanced biological P accumulation, etc.), as well as anoxic and anaerobic processes (denitrification, anaerobic degradation, etc.) in the lower layers.

The system consists of ladder-like, rough-surfaced plates (1 ) with a large surface area on which the biofilm will form, arranged vertically from top to bottom in a zig-zag pattern (Figure 7 10). If the elevation of the waste water source is higher than the facility, it will come to the primary settling tank without pumping, where solids that can settle after appropriate retention time. If the waste water source is at a point below the system, pumping will inevitably be used for elevation as in every system. Inlet waste water with high dissolved substance content will flow from the main pipes (5) to the treatment plant from the top of the system onto the plates (distributor) through the inlet water pipes (7). Thus, biofilm formation mechanisms will work on the rough surface plates (1 ), and the biofilm system, which starts with aerobic processes together with the free oxygen gained from the atmosphere, will thicken and anoxic and anaerobic layers will also form.

Starting from the area where the wastewater flows, a biofilm will begin to form on the plates (1 ) with a downward sloping rough surface, and over time, the biofilm will spread over all vertical cascade plates with low slopes. The plates (1 ), on which the biofilm will form, are attached to each other by steel pipes (9), which keep the plates fixed in the zig-zag position, provide support from each other and fix the rail system. Again with the same steel pipes (9), the motor that allows the sludge scraper to move between the plates (1 ) and the channeled rail system (3), in which the ball wheel at the end advances, is intermittently attached so that the rail is not occupied. In this way, the rail system , which also enables the sludge scraper to progress, consists of upper and lower strips, and the strips are attached from the edge and right in the middle of the plates ten times thicker than themselves on each floor. Thus, the gaps between the strips on the rails will remain between the strips and the motors (2) that allow the sludge scraper to move forward by rotating the ball wheels (15) connected to the scraper motor shaft, to which the scrapers are connected. Wastewater flowing on the plates will drain from the large holes (12) to a lower plate and biofilm formation will occur in the lower layers depending on the character of the water until the wastewater is fully treated. Wide holes (12) on the plates that allow the passage of water flowing to a lower plate are designed like a funnel and this structure will create a slope from the plate surface to the holes, catch the water flowing from the surface, and allow the water to flow down. These holes (12) that allow the passage of water flowing on these plates to a lower plate are large and can be opened easily with a stick in case of accumulation of sludge. Even if the large holes on the plates accumulate sludge, the treated water will seep through these holes flowing down through the sludge and treatment can continue. Since the biofilm that will form on the plates will have a large contact surface with the atmosphere, it will gain oxygen from the atmosphere and oxygen will be supplied to the bacteria forming the biofilm. Bacteria will continue their catabolic and anabolic metabolisms by supplying organic carbon and nutrients (nitrogen and phosphorus) from wastewater. Along the thickening biofilm over time, oxic, anoxic and anaerobic zones will form from the surface down, respectively. The formation of these zones will also be effective in biological nitrogen and phosphorus removal. Excess sludge, which is a part of the biofilm layer that thickens over time, will be scraped in the direction of wastewater flow with the periodic movement of the sludge scraper pallet (4) and taken to the settling tanks (10) where the treated water is collected.

A corrugated (wavy) surface formation will be used to increase the surface area on the plates. In addition, it will be ensured that the surface is somewhat rough. In order to ensure that the scraped sludge passes to a lower plate, a gap (6) is provided in the area where the plates come into contact with each other, where the scraper can pass while rotating, at the junction point of the plates, which allows the scraper to pass to the bottom plate. The scraped sludge will fall into the settling tank before it can go down to the areas where the scraper turns. The scraper will be operated intermittently and at different periods depending on the biofilm formation rate. Since the scraper blade will operate periodically and its speed will be slower than the flow rate of the flowing waste water, the small amount of water it carries with the excess sludge during the scraping process will not adversely affect the treatment.

After the biofilm matures in the system, the wastewater transmitted from the inlet pipes (7) to the top plate will be exposed to aerobic, anoxic, and anaerobic zones in the biofilm while flowing through the plates. In the aerobic zone, carbon removal and aerobic ammonia oxidation (nitrification) will occur. The nitrates formed will be transformed into nitrogen gas by denitrification in the anoxic regions of the lower layers of the biofilm and nitrogen removal will be achieved. The treated wastewater will flow into the settling tanks (10) where the scraped sludge and the treated water are collected, and after a settling period, the treated water will be discharged through the discharge pipe (14). The stabilization of the system and the maturation of the biofilm will take some time depending on the climatic conditions of the region where the plant is located. When the biofilm matures under steady-state conditions, the effluent will meet the receiving environment discharge standards. The sludge accumulated in the settling tank will be taken from the outlet pipes (11 ) that provides the collection of the settled waste sludge and will be sent to the sludge disposal unit(s). Figure 10 shows how the sludge scraper moves at the turning point between the plates with the help of the motor (2) that provides the move of the sludge scraper. The scraper blade (4) will become horizontal as it rotates through the gap (6) that allows the scraped sludge to pass to the lower plate in the junction area of the plates, and the scraped sludge will fall down into the settling tank during the rotation. When the scraper pallet completes its return to the down plate, it will become vertical again and start to scrape the bottom plate.