RO131971B1 - Waste water treatment device - Google Patents

Description

RO 131971 Β1

The technical field of application of the present invention is that of waste water treatment devices through a drain bed or through a biofilter.

A device of this type is known, which has the purpose of purifying waste water. Thus, the patent FR 2895394 describes a device 1 which comprises a treatment chamber 2, inside which, in the upper part, a supply channel 3 and 4 for waste water opens. Treatment chamber 2 is organized to provide a hybrid treatment, either through a trickling bed or through a biofilter. A perforated conical plate 5 serves to distribute the waste water homogeneously in the upper part. The filtering means are constituted by the storey modules 6, 6' and 6, at a distance D between two consecutive modules. These modules comprise a retaining member 7 which forms a perforated plate of a filter material 8. This plate allows a drain of water from one module to another. The retaining member 7 and the material 8 are integrated in a skeleton 9 attached to the interior of the chamber 2.

Chamber 2 is provided with two discharge channels 10 and 11 of the treated water after its flow through the modules 6. Channel 10 is provided at the base of chamber 2, and channel 11 in the upper part of the chamber. These channels are equipped with the respective valves 12 and 14 which, in the open position, ensure a flow of purified water to the outside.

It is noted that when valve 12 is open and valve 14 is closed, the device functions as a trickling bed, while when valve 12 is closed and valve 14 is open, the device functions as a biofilter.

A discharge pump 13 is provided to direct the treated waters to another point of the treatment plant when necessary, the valve 12 being in the closed position.

An oxygenation device 16 is provided at the base of the chamber 2 to regulate the operation of the device in the biofilter mode.

The control means 15 are provided for the control of the various valves 12 and 14, the oxygenator 16 and the pump 13.

This device has disadvantages in both trickling bed and biofilter operation. It is recalled that the drainage bed is based on the drainage through a sprinkler system of the water to be treated, previously decanted, over a mass of porous or cavernous material that serves as a support for the purifying microorganisms. Aeration is generally achieved by natural draft. The filter mass must not be submerged (stopping the aerobic function).

WO 2011/058566 relates to a biological reactor comprising a waste water inlet, several filter cells and a treated water outlet. Each filter cell comprises a frame and several screens fixed to it on which the biological filter material is arranged. The bioreactor includes means for dislocating the solids formed on the substrate, thus preventing the formation of an excess of solid substances and their removal. These means of dislocating the solids are vibrators, brushes, means of aeration, stirring, etc.

Also, US 2004/0226897 relates to an apparatus for filtering fluids comprising a container for fluid a fluid inlet port a filter medium located in a housing, at least part of the housing being flexible and containing a medium for compressible filtration, an opening in the housing that allows the fluid to enter and an outlet for the filtered fluid. Agitation means are also provided to dislodge the solids that have adhered to the filter medium and to remove the fluid containing these dislodged solids during the operation of these devices the risk of clogging and the production of unstabilized sludges is real.

in reality, the waters to be treated carry suspended matter which, over time, risks causing a blockage of the porosity of the bed. The sludge produced accelerates this clogging process. As a result, this requires the construction of an effective pretreatment and primary settling upstream of the bed. in addition, except for low load beds

RO 131971 Β1 or if the acceptable hydraulic flow rate is too low, a high hydraulic load must be applied that exceeds the minimum self-cleaning flow rate (0.5...0.6 m ³ /m ² /h) .

Sludge produced in a low loading bed does not require stabilization. instead, sludges 3 produced by high-load beds, in quantities comparable to activated sludge processes, must be stabilized. 5

Controlling natural draft is difficult and produces strong odors. This draft depends on the temperature difference between the bed and the external environment. in certain periods of the 7th year, there is thus a risk of oxygenation that leads to fermentation in areas with reduced exchange and the production of unpleasant odors. Fermentation is accelerated by 9 gradually clogging the bed, so covering and mechanical ventilation is necessary.

This involves high investment costs. 11

Bacterial bed processes require major civil engineering work. For a station of 1000 equivalent inhabitants, the investment cost is of the order of €220/equivalent inhabitant, or 80% of the investment cost for an activated sludge process.

Biofilters are recent intensive biological processes (chemical reaction rates are 15 high). They provide a double function:

- the biological transformation of organic and nitrogenous matter by fixed bacteria; 17 - physical retention of suspended matter, especially excess produced sludge.

in functioning as a biofilter, the disadvantages are associated with poor control of clogging and the production of unstabilized sludges.

The filtration phenomenon associated with excess biomass production due to depollution 21 involves a progressive clogging of the biofilter. Flushing sequences (1 to 2 times a day) are essential for the proper functioning of the fixed bed biofilter. in contrast, the risk of clogging 23 is significantly lower in moving bed biofilters.

It is noted that washing is the only operation in sludge production: for an average chemical oxygen consumption (COD) yield of 67%, 0.40 kg SU/kg COD removed compared to 0.7 kg SU/ kg COD removed produced by the 27 activated sludge process. These sludges, after storage in a basin, must be subjected to a stabilization treatment. 29 in addition, maintenance should be frequent for good efficiency.

For a treatment system that includes a physical-chemical pre-treatment followed by a 31 biofilter, the current maintenance is 500 to 2000 hours/year. This is comparable to that of a medium loading activated sludge process. 33

This treatment requires the presence of qualified persons. This intensive process requires close monitoring to prevent operational disturbances and to control clogging. apart from a safe automation and a reliable alarm, the operating personnel must be qualified in the maintenance and control of the electromechanical equipment. 37 finally, energy costs are very high. The energy consumption is of the order of up to 4 kWh/kg COD. 39

The average annual operating cost is high and of the order of 15 to 20% of the investment cost, from €27 to €36/inhabitant equivalent/year. 41

Investment costs are also high, on the order of 20 to 30% higher than for an activated sludge process. 43 190...220 €/equivalent inhabitant must be counted on for a treatment facility of 50,000 equivalent inhabitants.

However, investment and operating costs are difficult to assess, 45 as they are highly case-by-case. The above figures are given for informational purposes only. 47

RO 131971 Β1

The role of a washing phase of a biofilter is to restore its initial assimilation capacity: it must be effective enough to entrain the suspended solids and detach a certain thickness of the biofilm. There are, depending on the technologies used, several types of washing: so-called normal washings, mini-washings, exceptional washings.

A normal wash is generally carried out in several stages:

- loosening by blowing air with high flows;

- actual washing, by detaching and entraining the biofilm and suspended matter through a mixture of air and clean water;

- rinsing with clean water.

The clean water used for the washing steps is purified water stored in a so-called clean water pool located downstream of the biofilter or even above the biofilter. The amount of water required for a wash is of the order of 2.5 m ³ of water/m ³ of material to be washed.

The washing step is an essential step in the overall operation of a biofilter. This must be perfectly controlled, as it can cause a possible loss of material if the flow rates are too high, or it can cause washing frequencies that are too close together if the washing is not good enough.

It is worth noting that all the technological advances proposed by biofilter manufacturers have been and are oriented towards better management of clogging and washing; from the point of view of operating costs related to washing, it is easy to understand that the main objective is to wash better at lower costs.

during the washing of a biofilter, wastewater continues to enter the installation: several biofilters must be installed in parallel to ensure continuity of treatment.

The minimum number of reactors is 4; this is explained by the fact that, when one of these biofilters is being flushed, the effect of distributing its flow to the other 3 filters represents an increase of just over 33% to the filtration flow; while it would represent 50% for a station with only 3 biofilters or 100% if there were only two biofilters.

Distribution of waste water, wash water, recovery of dirty water and clean water, distribution of process air and wash air to the various biofiltration units involves the use of complex circuits comprising pumps, compressors, remotely controlled valves, as well as a large number of reinforcements. The management of these circuits, as well as the programming of washing cycles, are automated steps.

It is the object of the present invention to provide a device which overcomes the disadvantages described at length and in detail above.

As a result, the object of the invention is a device for the treatment of waste water having a treatment chamber inside which step-by-step filter modules are arranged, the said chamber being equipped with two exhaust pipes: low and high, respectively equipped with valves, characterized by that it comprises a frame disposed in the chamber and mounted therein by means of a damping means, a vibrating element of said frame and a large opening exhaust pipe.

According to a feature of the invention, the damping means is constituted by an elastic element.

According to another feature of the invention, the chamber is provided with an element for receiving the damping means and the frame.

advantageously, the chassis is in the form of a stainless steel tub.

RO 131971 Β1

According to another feature of the invention, the exhaust pipe is equipped with a quick opening valve, the pipe having a diameter of about 350 to 500 mm. Advantageously, the valve is a slide valve, solenoid valve or pneumatic valve.

According to another feature of the invention, the vibrating element is eccentric, rotating or impact type, with compressed air or electromechanical.

According to another feature of the invention, the discharge pipe provides a sewage entrainment effect.

According to another feature of the invention, the device comprises control means 9 to command the opening and closing of the various valves, the activation of the vibration means and an oxygenation means and the activation of a discharge pump. 11

A first advantage of the present invention consists in the automatic control of the operation of the device, without the intervention of qualified personnel. 13

Another advantage is the use of simple means to ensure the separation of sludge that clogs the filters. 15

Other features, advantages and details of the invention will be better understood from reading the following additional description of an exemplary embodiment, with reference to 17 a drawing in which fig. 1 shows a longitudinal section of the device.

in the description that follows, the elements described above in stage 19 of the technique will be repeated, indeed, the device according to the invention is an improvement of the previous device, and the common references have been maintained. 21 for this purpose, the device 1 additionally comprises a frame 7, in which the filter elements 8 are arranged. This frame is inserted into the treatment chamber 2 and spaced from it. This treatment room is in the form of a concrete basin. This frame 7 rests on a support 20 fixed in the inner wall of the chamber 2, at a certain distance from its bottom 25. The frame 7 rests on this support 20 by means of a damping means 17 consisting of an elastic element. The purpose of this means 17 is to isolate frame 7 from 27 room 2.

Advantageously, the frame 7 has the shape of a stainless steel tub. 29 in the figure, it can be seen that the perforated plate 5 is provided at the base with a deflector 21 for directing waste water only to the frame 7. 31

The frame 7 has at its base a vibrating element 18 which transmits vibrations to it as will be explained below. The vibrating element 18 can be of the eccentric, rotary or impact type, with compressed air or electromechanical.

Chamber 2 is additionally provided with an exhaust pipe 19 with a large opening 19a, equipped with a quick-opening valve 19b. This pipe 19a may have a diameter of about 350 to 500 mm, to ensure almost instantaneous complete emptying of the frame. Thus, the discharge pipe 19a provides an effect of entrainment of waste water. The valve 19b can be a drawer valve, solenoid valve or pneumatic valve. 39

All these additional elements are connected to a control means 15 to command the opening and closing of the various valves 12, 14, 19b, the activation of the vibrating element 41 18 and the oxygenation means 16 and the activation of the discharge pump 13. Thus, the control means 15 will be able to close the valve 14 and open the valve 12 to ensure an operation 43 of the device 1 as a fluidized bed. On the other hand, this means 15 will be able to close the valve 12 and open the valve 14 to ensure an operation as a biofilter, in interaction with the oxygenating means 45, to bring oxygen continuously, so that the medium remains permanently in conditions aerobic. 47

RO 131971 Β1

The cleaning sequence is performed as follows. The vibrating element 18 is controlled, which vibrates the frame 7. This vibration causes the filter elements 8 to unclog the sludge accumulated on the surface and between them. After a certain period of vibrations, with the help of the control means 15, the opening of the valve 19b is commanded, and the large opening of the pipe 19a ensures the entrainment of all the sludge, in order to completely empty the frame 7. This operation allows a physical break of the biofilm remaining on the elements of 7 filtration and of the slag previously shaken and mechanically separated by the vibrating element.

Obviously, during this operation, valves 12 and 14 are closed.

It goes without saying that if device 1 is in biofilter mode, it is previously set to bed mode by closing valves 12 and 14.

The cleaning done is indispensable, because this is an essential step for the good functioning of the device 1 (cost-efficiency-functionality) of a biofilter or a 13 fluidized bed. Thanks to this innovation, the cleaning operation is very simple and is much less expensive compared to an existing system.

Claims (9)

RO 131971 Β1 Claims 1 1. Device for the treatment of waste water comprising a treatment chamber (2), inside 3 of which tiered filter modules (6, 6', 6) are arranged, said chamber being equipped with two exhaust pipes: low (10) and high (11) respectively equipped with 5 valves (12, 13), characterized in that a frame (7) is arranged in the treatment chamber and is connected to it by means of a damping means (17), an element 7 vibrator (18) of the frame (7) and a large-opening exhaust pipe (19a), said frame containing filter elements (8), the large-opening exhaust pipe 9 (19a) ensuring complete drainage of the frame (7). 2. Device for treating waste water according to claim 1, characterized in that the damping means (17) is constituted by an elastic element. 3. Device for treating waste water according to claim 1 or 2, characterized 13 in that the chamber (2) is provided with a supporting support (20) of the damping means (17) and the frame (7). 15 4. Device for treating waste water according to claim 3, characterized in that the frame (7) is in the form of a stainless steel tank. 17 5. Device for treating waste water according to any of the preceding claims, characterized in that the discharge pipe (19a) is equipped with a quick-opening valve (19b), the pipe having a diameter between 350 and 500 mm. 6. Device for treating waste water according to claim 5, characterized in that the valve (19b) is a drawer valve, solenoid valve or pneumatic valve. 7. Device for treating waste water according to any of the preceding claims 23, characterized in that the vibrating element (18) is of the eccentric, rotary or impact type, with compressed air or electromechanical. 25 8. Device for the treatment of waste water according to any of the preceding claims, characterized in that the discharge pipe (19a) provides an effect of driving the waste water. 9. Device for treating waste water according to any of the preceding claims, characterized in that it comprises control means (15) to command the opening and closing of the various valves (12, 14, 19b), the activation of the vibrating element 31 ( 18) and the oxygenator (16) and activation of a discharge pump (13).