GB2380474A

GB2380474A - Water processing apparatus

Info

Publication number: GB2380474A
Application number: GB0123649A
Authority: GB
Inventors: John Patrick Hynes
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-02
Filing date: 2001-10-02
Publication date: 2003-04-09
Anticipated expiration: 2021-10-02
Also published as: GB2380474B; GB0123649D0; WO2003029154A1

Abstract

Apparatus for processing water that has been used for food processing uses a self cleaning backwash filter (20) to remove solid particulate matter before pumping the water into a filter bank (40) including multiple stages of which at least one (108) is a carbon filter. The output quality of the fluid flow is monitored so that if the monitored component exceeds a preset level flow can be diverted from the main drains or recycling into a storage tank while the line is shut down or diverted to a second production line (40'). The apparatus will be made in a self contained 316 stainless steel framework (10). The filters may be flushed with disinfectant to prevent bacterial growth. The apparatus may also contain a UV unit.

Description

Water Processing Apparatus Background of the Invention The present invention relates to equipment that can be used to process water so that it can be recycled or is acceptable under environmental standards for disposal to the foul water drain.

Prior Art Systems for processing grey water stored in a tank and delivering a potable drinking water have been described, for example in GB-A-2350357. This patent application discloses apparatus for performing a sequence of treatment steps including a series of filters with reducing fineness, an active carbon filter, UV and reverse osmosis treatment steps. The application also discloses the option of an optical sensor downstream of a carbon filter for indicating when the degree of clarity is below a predetermined value and other sensors upstream of a reverse osmosis unit.

The present invention is particularly concerned with processing a continuous flow of water that has been used in industrial processes in the food industry and in particular for washing salad, fruit and vegetable products. Such water will contain bacteria, antibodies, chemicals, colour, odour and other impurities including some solid matter such as fibres.

Technical Problem While fluids filters exist which are capable of removing various sized particles, technical problems exist when the water being processed contains a variety of particulate material of differing sizes.

In a factory environment, it is not practicable to store large quantities of waste water for treatment in a tank and therefore there is a demand for a system capable of continuous operation for sustained periods with substantial flow rates of the order of tens of thousands of litres per hour.

In UK patent application GB0106580. 4, unpublished at the date of filing this application, it is proposed to pass the waste water from food processing to a pump that feeds a sequence of filters with gradually reducing filter sizes. However, by pumping the waste water before passing it through the primary coarse filters, backwash problems are encountered with the blockage of the pump.

Because of stringent legal requirements on the content of water passed to the foul water drain, it is necessary to keep a record of the output water quality so as to avoid infringements. This is distinct from the desire to monitor conditions during intermediate stages of the processing, which may be needed to determine when components need replacing or maintenance as described in GB-A-2350357. The monitoring of output water quality is also of importance if the output is to be used for recycling. This also presents technical problems, which are addressed by the present invention.

In accordance with the present invention there is provided a water processing apparatus having an input adapted to receive a continuous water flow and an output, a self-cleaning backwashing filter set to provide a coarse filtration level connected directly to the input, a pump connected to receive water output from the self-cleaning backwashing filter, a multi-stage filter bank connected to receive water output from the pump and for passing the water through at least two filter stages of different filtration levels where at least one of the filter stages comprises activated carbon, and a monitoring device adapted to receive water at the output of the apparatus for monitoring the amount of at least one chemical or biological component of the output water to monitor the effectiveness of the processing in reducing that component.

The apparatus may also include a UV unit to kill bacteria if the output is to be recycled.

Preferably pressure gauges give a reading as to how the filters are performing.

The apparatus also further preferably comprises means for activating a dosing pump for flushing the filtration system with a disinfectant to prevent bacterial growth in the

filters when the flow of waste water at the input is interrupted.

Brief Description of the Drawing In order that the invention may be well understood an embodiment thereof will now be described, by way of example only, with reference to the accompanying diagrammatic drawing, in which: Figure 1 is a block diagram showing an embodiment of an apparatus in accordance with the invention.

Overview The apparatus to be described is for the purpose of processing the water used for washing vegetables such as salad, garlic or beetroot in a washing production line. It will be appreciated that the apparatus has other applications where a similar flow of water containing particulate material ranging from fibres of significant size to microscopic particles including large molecules responsible for colour and odour is required to be continuously processed. For such an application it is necessary to be able to process water flows in the range 10,000-40, 000 litres of water per hour or more in a single unit which has an input 2 that can be simply connected to the output of the washing production line and an output 4 that can be coupled to the foul water drain or a recycling system.

All of the necessary components for the apparatus are assembled and supported in a purpose-made stainless steel structure or framework 10. For use in the food processing industry all components are manufactured from 316 stainless steel. A unit designed for processing up to 10,000 litres of water per hour can be assembled within a framework 10 that is approximately three metres wide, two metres high and two metres deep. All pipe work and fittings within the unit will also be made of 316 stainless steel.

The components within the framework 10 are a self-cleaning backwash filter 20, a pump 30 having its input connected to the output of the self-cleaning backwash filter

20, a filter bank 40 connected to the output of the pump 30, a UV unit 50 and a monitor 60 for monitoring the output 4. At the output 4 of the unit a diverting valve 70 is provided so that the flow can be directed to a pipe 80 leading either to the foul water drain/recycling path or to a pipe 90 leading to a temporary storage tank. The unit also includes a control panel 100 for connection to a three phase electrical supply (not shown). The control panel incorporates a computer and controls for the electrical supply.

Self-Cleaning Filter In order to cope with the solids entrained in the input fluid flow, it is first drawn through the self-cleaning backwash filter 20 by the downstream pump 30. Suitable self-cleaning filters are readily available. This type of filter provides a coarse level of filtration, which can be chosen in the range 25-60 microns depending on the application. The filter element is continuously cleaned and the solid debris passed to a sump 102. This filter 20 is electrically operated. The sump 102 collects solids and automatically backwashes into a twin lined perforated stainless steel tray 103 where the solids are retained and the water released into a drain/recycling path or to the temporary storage tank. The twin lined perforated stainless steel tray 103 is removable so that it can be emptied. The coarse filtration level is set to remove fibre components and other solid particles such as husks removed from garlic or ginger fibre or other vegetable material from the washing production line. The output from the filter 20 is connected to the pump 30.

Pump A suitable pump 5-10 bar 30 is a vertical multi-stage centrifugal pump. However, it will be appreciated that any other pump design capable of handling the required flow capacity and meeting the necessary hygiene standards could be used instead.

The pump must be positioned downstream of the first coarse filter to protect it from blockages that would otherwise be caused by the larger material particles.

Filter Bank The filter bank 40 is set up as a multi-stage bank where the filtration level of each stage is stepped down. For use in the food industry, it has been found that a three or more stage filter where the first stage 104 is a 5 micron particulate filter, the second stage 106 is a 1 micron particulate filter and the final stage 108 a 0.5 micron activated carbon filter is effective. Each filter stage is made up of a rack of pot filters having replaceable cartridges. The number of filters and pots used is selected in dependence on the throughput. The 5 micron filters can be filter cartridges of pleated polyester.

The 1 micron filter cartridges are of a glass fibre material. The 0.5 micron cartridges are activated carbon. Such filters are readily available.

A typical filter bank for a 10,000 litre per hour flow could be 1 x 6 pot unit 5 micron filter followed by a stage of 1 x 6 pot unit 1 micron particulate filter followed by 1 x 12 pot unit 0.5 micron carbon filter. Each unit is 40 inches (102cm) in height.

For a 20,000 litre per hour flow the following configuration would be suitable-a first stage made up of a 12 pot unit, the second stage a 12 pot unit and the third stage of two twelve pot units. By increasing the number of units and/or their sizes, it will be appreciated that the bank can be adapted to provide any suitable flow capacity.

The filter bank and in particular the carbon filters remove the chemical components responsible for the colour and odour of the water. Typically there may be restrictions on the disposal of waste containing such chemicals.

The type of contaminants in industrially used water in the food processing industry tend to have a profile that covers larger items of vegetable matter, fibre, grit and other debris and smaller chemical and biological components. The first coarse backwash filter 20 removes the former components so that the filter bank 40 can be started with a relatively fine 5 micron filter. It has been found possible to eliminate the intermediate filtration step sizes while maintaining the efficiency of operation.

A UV unit 50 may be provided to process the output from the filter bank 40 if bacteria

removal is required. If the output 4 is being sent to the foul water drain, it may not be necessary to remove bacteria at this stage.

Monitor In order to provide an assay of the output water quality a monitoring device 60 is provided, which can be used to control the diverter valve 70. The device 60 can be set to monitor for specific identified chemical or biological components. A suitable monitoring device is one which uses magnetic resonance technology and which can be set to detect the level of various chemical or biological components in the flow at the output 4. A suitable water quality monitor is the EP2T20 offered by Aurora Technical Trading Limited of Waterlooville, Hampshire. This device is capable of detecting bacteria, chemical impurities and water hardness.

Calibration and commissioning When the EPT20 is mounted in position and its power supply and RS232 connected, the software supplied with the unit should be loaded on to the computer and the ADC16 selected from the converter menu.

The EPT20 can now be calibrated using samples from the process it will monitor, and spiked samples can be used to set the alarm levels. The system can then be connected to the process and placed into service.

Monitor Specification Housing: Constructed from FMB stainless steel to IP65 Sampling : 10mm o. d. plastic tube chosen to suit the application Sampling rate: 1 sample per second upwards, selected by menu Power supply: 15 VDC at 100mAs Sensitivity: 100 parts per billion Display: Graph or spreadsheet

Notes on accuracy and repeatability of magnetic resonance instrumentation The EPT20 range is tested using depolarised water and the output signal is set at 1000 millivolts. Due to the sensitivity of the EPT20 it has been found that the variation in standards of commercially obtained depolarised and demineralised waters is quite wide, and when an EPT20 is tested when installed on site and tested with depolarised water the readout may vary from the factory setting. However, the solution is to use a band of about 10 millivolts so that the reading of 995 to 1005 can be used to accept the testpoint.

Using accurately spiked samples, the EPT20 can be easily calibrated and the readout personalised for the application.

When the system is installed and first run a digital indicator will indicate the voltage for that water condition. A control will be used to change that signal to 1000. This will make the sensor setpoint for the Clean Water Condition, and this signal will be fed into a differential amplifier, the other signal in the amplifier being a Standard Reference. The output of the amplifier will be zero when both signals are equal and that condition is a Clean Water Condition. The amplifer will have an adjustable gain control which will have a spiked sample bacteria and from this the alarm level will be set and a relay energised which will indicate on the housing and provide a remote signal contact which can be used to stop the system.

For example, if the apparatus is being used to process water that has been used for washing garlic then before the flow can be discharged to the foul water drains, it is necessary to ensure that the level of the chemical responsible for the garlic odour has been reduced to environmentally acceptable levels. This type of monitor can be provided with a DIN output so that the level can be continuously monitored using an external computer system throughout operation of the apparatus to provide a permanent record. If the level of the selected chemical is above preset limits then the control system can be set to divert the flow using the diverter valve 70 into a temporary storage tank while the line is shut down. Alternatively a second filter bank 40'line can be installed from the pump 30 to allow the process to continue

uninterrupted. In this case a diverter valve is provided upstream of the main filter bank 40 to divert the flow to the second filter bank 40'.

Protection of the carbon filter stage The carbon filters may be susceptible to bacteria breeding when the apparatus is not in use. A dosing pump 200 is provided for flushing a viracidal disinfectant through the system. The control system 100 can be set so that on closing down of the washing production line the unit is first flushed with clean water and then with the diluted disinfectant, which inhibits or prevents bacteria growth in the filter stages.

Use and Control of the Apparatus It will be appreciated that such a unit can be controlled in a known manner to provide for automated operation. Flushing of the filters with a viracidal disinfectant on shut down can be controlled in a known manner. The unit will be set up so that pressure readings are taken on the filter housings to ensure correct functioning.

Use of such a unit in a washing production line allows the water used to be discharged lawfully to the foul water drain and/or recycled. The filter components can be selected depending on the particular contamination created during the washing process. Since the likely biological or chemical contaminants are known, the monitor 70 will be set to test for these components so that operators are able to take provable steps to ensure compliance with environmental waste regulations.

Although the unit uses some pre-existing components that are commercially available, the problem of dealing with continuous volume flow in an effective manner has not previously been solved.

Claims

Claims 1. A water processing apparatus having an input adapted to receive a continuous water flow and an output, a self-cleaning backwashing filter set to provide a coarse filtration level connected directly to the input, a pump connected to receive water output from the self-cleaning backwashing filter, a multi-stage filter bank connected to receive water output from the pump and for passing the water through at least two filter stages of different filtration levels where at least one of the filter stages comprises activated carbon, and a monitoring device adapted to receive water at the output of the apparatus for monitoring the amount of at least one chemical or biological component of the output water to monitor the effectiveness of the processing in reducing that component.
2. Apparatus as claimed in claim 1, further comprising means for activating a dosing pump for flushing the filtration system with a disinfectant to prevent bacterial growth in the filters when the flow of waste water at the input is interrupted.