FR2779712A1 - Continuous biological treatment of liquid effluents, especially from motor vehicle washing - Google Patents

Abstract

Continuous biological treatment of liquid effluents comprises withdrawing the effluent from a storage tank, passing it through a filter containing bacteria and either: (a) recycling part of the treated effluent to the storage tank and discharging the rest; or (b) recycling all the treated effluent when the liquid level in the storage tank reaches a predetermined minimum. An Independent claim is also included for apparatus for carrying out the process, comprising a storage tank, a filter and a device for detecting a predetermined minimum liquid level in the storage tank and recycling all the treated effluent.

Description

The present invention relates to a method of biological treatment in

  continuous liquid effluent, by passing through a filter containing bacteria.

  It also relates to an installation for the implementation of this process. This process and this installation are particularly, but not exclusively, intended for the treatment of waste water from washing chassis,

  motor vehicle engines and bodies.

  The main objective of the present invention is to provide a process and an installation which are efficient in terms of the quality of the treated effluents rejected,

  of the environment and low energy consumption.

  These objectives are achieved in accordance with the invention.

  The process to which it relates is a biological treatment process using

  continuous liquid effluent by passage through a filter containing bacteria.

  It is essentially characterized by the fact that it consists in: - continuously removing said effluents in a storage tank; - make them pass through said filter; - at the outlet of the filter, recycle part of the treated effluents in said storage tank and evacuate the rest, for example in a pipe; - only when a predetermined low level of effluents in the tank

  is reached, recycle all the effluents treated in said tank.

  The total or partial "recirculation" of the effluents in the tank makes it possible to homogenize the content, to ensure continuous aeration of the effluent to be treated and to compensate the acidification by buffering effect of the treated effluent by its repetitive passage at

through the filter.

  In addition, the total "recirculation" of effluents in the reservoir when the level of the latter is low makes it possible to maintain the continuous operation of the installation,

  until new effluents come into the tank.

  Furthermore, according to other advantageous but non-limiting characteristics: - said bacteria are aerobic bacteria fixed on a support; - Said bacteria are chosen from the group consisting of Gram + bacilli, Gram- bacilli, Gram + shells, Bacillus and Lactobacillus, Pseumodonas, Acinobacter, Vibrio, Aeromonas and mixtures thereof; - Said support is chosen from the group consisting of porous calcium carbonates enriched with trace elements, hydrated alumina silicates containing alkali and alkaline earth metals and anamorphosed potassium alumina silicates; - from time to time, for example every twenty-four hours, we reverse

  the direction of flow of the effluents in the filter for cleaning.

  As stated above, the invention also relates to an installation

  for the implementation of this process.

  This installation is essentially characterized by the fact that it comprises: - a storage tank for the effluents to be treated; - a filter for treating said effluents; means for detecting a predetermined low level of effluents in the

  tank and recycle all the effluents treated in the storage tank.

  According to other preferred but non-limiting characteristics of this installation: - said detection means consist of mercury ball detectors; - It includes means for detecting a low level of security inside the tank, which trigger visual and / or audio information means; - It includes means for detecting an overflow level inside the tank, which trigger visual and / or audio information means;

  - It includes means for detecting clogging of the pipes.

  Other characteristics and advantages of the invention will become apparent on

  reading of the detailed description which follows of a preferred embodiment. This

  description will be made with reference to Figure 1 attached which is a block diagram of

  the structure and operation of the treatment facility.

  The installation shown in Figure 1 attached is for example intended for the treatment of waste water from washing vehicles, water loaded with

  hydrocarbons or other industrial effluents.

  This installation includes a storage tank 1 for the effluents to

  treat. Its dimensions are sufficient to accommodate a large volume of effluents.

  This reservoir receives the effluents through a pipe 7 which is connected by

  example to a sludge collector and to an oil and petrol separator not shown.

  With the help of these treatment equipment located upstream of the tank,

  the effluents of some of the pollutants they contain.

  Furthermore, the tank is equipped with level detection means 5

  high and low level detection means 6.

  These are for example sensors of the mercury ball type.

  The means 5 comprise a detector 51 above which an overflow level detector 50 is provided, connected to visual and / or audio information means. Similarly, the means 6 comprise a sensor 60 for detecting a predetermined low level of effluents in the tank, and a low security level sensor disposed slightly below the previous one. The sensor 61 is connected to

  visual and / or audio media. We will explain later in the description

the advantage of such sensors.

  The installation also includes a filtration unit 2. This has

  the appearance of a sealed box which contains a biological filter 20 for aerobic bacteria.

  They are preferably bacteria fixed on a support. Among the types

  possible supports include porous calcium carbonates enriched in oligo-

  elements, hydrated aluminas silicates containing alkali and alkaline metals

  earthy and anamorphic potassium aluminas silicates.

  The bacteria which can be used in the process and the installation are, according to the invention, for example chosen from the following bacteria: Gram + bacilli, Gram- bacilli, Gram + shells, Bacillus and Lactobacillus, Pseumodonas,

  Acinobacter, Vibrio, Aeromonas and mixtures thereof.

  In a preferred embodiment, the filter contains bacteria according to the following distribution (percentages by weight): - 50% of Bacilli Gram +; - 36% of Bacillus Gram-; - 7% of Gram + shells;

  - 8% of a mixture of Bacillus, Lactobacillus, Pseumodonas, Acinobac-

ter, Vibrio and Aéromonas.

  At the lower part of the filtration unit is provided an air supply pipe 4 in the lower part of the filter. This air is of course intended to make the

fully operational bacteria.

  A manually operated V3 valve is also provided in part

  bottom of unit 2, for possible emptying.

  In the tank 1 plunges a pipe 30 whose lower end is provided with a strainer 10. On this pipe is provided an electric pump P with a single operating direction. Another pipe 31 is connected to the pipe 30, the second end of which opens inside the filter 20 of the unit 2, at the bottom of the latter. From its first to its second end, said pipe comprises

  a solenoid valve EV1, a valve V1 with manual operation as well as a check valve

  back C4. A pipe 35 is provided at the upper end of the filter 20 and its second end opens at the water distribution network, for example via a sewer T. On this pipe are provided an electro-valve EV3 as well as a

  manual operating valve V2 and a pressure gauge.

  A pipe 32 connects the pipes 31 and 35 between the inlet and the outlet of the unit 2 this pipe is equipped with two solenoid valves V4 and V5, as well as

two check valves C2 and C3.

  Between these two valves is provided a pipe 33, the second end of which is connected to a last pipe 36 connected to the top of the unit 2 and

  whose free end opens above the tank 1.

  On line 36, an EV6 solenoid valve and a valve are provided.

non-return C1.

  We will now describe the operation of the installation and the

method according to the invention.

  First, we will assume that the level of effluent E to be treated inside the tank 1 is between the sensors 51 and 60. In such a case, automatic means for managing the installation (not shown) , for example microprocessor, trigger the operation of the pump P so as to suck effluents in the pipe in the direction of arrow f. These effluents then pass through the pipe 31 and are admitted with a slight overpressure inside the

filtration 2.

  Inside the latter there is a biological degradation of the materials

  organic matter contained in the effluents by the micro-organisms present in the filter.

  There is also a mechanical filtration of the suspended matter, as well as a

  blocking of heavy metals by ion exchange.

  At the outlet of unit 2, part of the effluent flows into the pipe-

  tion 35 (arrow g) to be discharged into sewer T. Another part of these effluents is directed into line 33 via line 32 (arrow h). The effluents as well

  vehicles are discharged inside the storage tank.

  In this way, part of the treated effluent is recycled, while

  discharges the rest directly into the water distribution network.

  By proceeding in this way the effluents are recycled a certain

  number of times in the filter, so that their biological purification is ensured appropriately

  badly. When the level of effluents in the tank 1 reaches the level of the sensor 60, the control system of the installation cuts the electro-valve EV3 disposed on the pipe 35, so that it is all the effluents leaving of unit 2 which

  joins the tank, via line 33.

  It is then necessary to wait until the level of effluents in the tank 1 reaches that of the sensor 51, by the arrival of new effluents to be treated by the pipe 7, for

  that the pipe 35 opens again.

  If, for a reason of too great an arrival of effluents to be treated in the tank 1, the level of the sensor 50 is reached, the visual information means and / or

  sound signals connected to it warn an operator of the danger of overflow.

  Similarly, the low security level detection sensor 61 informs, via visual and / or audio information means that the level of effluents inside the tank is now too low for it to operates a

  normal operation of the installation.

  For the proper functioning of this installation, it is necessary to regularly rinse the biological filter 20. This rinsing removes the suspended matter retained in this filter as well as part of the bacterial mass

that develops there.

  If there is no rinsing, the filter will gradually clog up,

  causing an increase in pressure drops and slowing the processing rate.

  This operation is carried out by the counter-current circulation of

  effluents through the filter 20. This is called "backwashing".

  This circulation has been represented by the arrows f ′ in FIG. 1. During this process, the effluents pass through the pipes 30 and 34 to the filter then the pipes 32, 33 and 36 at the outlet thereof. The operation management machine

  of the installation causes for example this recirculation once every 24 hours.

  Advantageously, the installation can be equipped with means for detecting the blockage of the pipes. They can be thermal type detectors, capable of detecting an abnormal overheating of the pump P motor. It can also

  These are means capable of detecting the absence of circulation of liquid in the pipes.

  tions. These detectors are of course connected to an audible or visual alarm.

  Such an installation is operational 24 hours a day and 365 days a

  year. As an indication, its maximum discharge rate is around 2.4 m3 per day.

  The quality of the treated effluents complies with the provisions in force on the matter, namely: - 5 to 10 mg / l of hydrocarbons, for the discharge of water into a public pipe connected to a treatment plant; 10 mg / l of hydrocarbons, when the wastewater is discharged in

  surface and for any discharge greater than 100 mg per day.

  The installations and process in accordance with the present invention implement a concept of modern purification and natural inspiration guaranteeing a high purification yield. They have great autonomy and high operating reliability. They do not cause any displacement of the pollution to be treated and no

  production of waste or sludge linked to the operation of the installation.

  Operating and maintenance costs are low. In addition, the costs of

  maintenance and monitoring are greatly reduced.

  The types of bacteria that can be used can be modified depending on the type of effluent to be treated. In addition, the specific rate of abatement of organic pollution is very high. The organic materials used are insensitive to the product of

  usual cleaning and the installation does not use any chemical reagent.

Claims (9)

  1. Process for the continuous biological treatment of liquid effluents (E) by passing through a filter (20) containing bacteria, characterized in that it consists in: - continuously removing said effluents (E) in a storage tank (1);   - make them pass through said filter (20) - at the outlet of the filter (20), recycle part of the treated effluents (E) in said storage tank (1) and evacuate the rest, for example in a pipe; only when a predetermined low level of effluents (E) in the   tank (1) is reached, recycle all of the treated effluents (E) in said tank (1).   2. Method according to claim 1, characterized in that said   bacteria are aerobic bacteria fixed on a support.   3. Method according to claim 2, characterized in that said bacteria are chosen from the group consisting of Gram + bacilli, Bacilli   Gram-, Gram + shells, Bacillus and Lactobacillus, Pseumodonas, Acinobac-   ter, Vibrio, Aeromonas and mixtures thereof.   4. Method according to claim 2 or 3, characterized in that said support is chosen from the group consisting of porous calcium carbonates enriched with trace elements, hydrated alumina silicates containing alkali metals and   alkaline earth and anamorphosed potassium alumina silicates.   5. Method according to one of claims 1 to 4, characterized in that,   from time to time, the direction of flow of the effluents in the filter is reversed in order to its cleaning.   6. Installation for the implementation of the biological treatment process   according to one of claims 1 to 5, characterized in that it comprises:   - a storage tank (1) for the effluents to be treated (E); - a filter (2) for treating said effluents; - means (60) for detecting a predetermined low level of effluents   in the tank and recycle all the effluents treated in the storage tank.   7. Installation according to claim 6, characterized in that said   detection means consist of mercury ball detectors.   8. Installation according to claim 6 or 7, characterized in that it comprises detection means (61) of a low level of security inside the   tank (1), which trigger visual and / or audio information means.   9. Installation according to one of claims 6 to 8, characterized in that   that it includes means for detecting (50) an overflow level inside the   tank (1), which trigger visual and / or audio information means.   1 O. Installation according to one of claims 6 to 9, characterized in that   that it includes means for detecting blockage of the pipes.