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Eurovac - Evacuated Food Waste

Bvac - Vacuum Food Waste - Storage Tank - Pipe Work

BVAC Vacuum Food Waste

A growing source of waste in the western world is from food, and all food waste has to be managed. We all do this in our personal life by separating our waste food matter in our homes and relying on a dedicated council collection to remove this. We all believe it’s the correct and environmental thing to do. But doing this on a commercial scale in restaurants, kitchens and food hall complexes produces a new set of challenges. One of these is getting all of the food waste from several areas of the building to a central location for collection. This is where vacuum plays its part once again as an efficient medium for conveying waste Using our expertise gained through our experiences in 50 years waste transfer in the transportation and building sectors, Bvac offer the vacuum food waste collection system.

Food waste generation can be up to as much as 3kg per day per person. The greenhouse gas emissions associated with avoidable food and drink waste in the UK are around 20 million tonnes of CO2 each year. However, food waste can be recycled to generate renewable energy and create a valuable bio-fertiliser using a process called anaerobic digestion. Not only is it a strain on the environment the storage of food waste inside bins in kitchen areas and corridors is also unhygienic and brings risk of cross contamination. Food waste fermentation starts quickly and it then generates unpleasant smells and toxic corrosive gases adding to this hygiene issue. In addition to this large numbers of bins and containers consume a lot of floor space. Even with dedicated collection, costs for disposal to landfill are both high financially and environmentally.

By using the Bvac food waste system, kitchen waste can easily be placed into a locally positioned feeding station. Using the same well established principles as the Evac Vacuum Drainage System, the waste is the transported through high level small bore piping to a collection tank. The waste will be stored at this point until a sufficient amount has been collected and then removed by truck and taken to an anaerobic digestion plant at significantly cheaper rate than landfill. Investigations have shown a probable saving of over £40.00/tonne of waste. Companies such as Biogen are able to collect and carry out this treatment. Once treated, the waste will generate renewable energy and return a valuable bio fertiliser to the land.

Summary

The Bvac Food Waste Vacuum System uses differential air pressure to transport food waste from food preparation areas and kitchens to a holding waste tank located in a technical or waste management area of the building. As vacuum is the means of conveying the waste, pipe work can rise upwards and be run in overhead ceiling voids thus, avoiding floor penetrations and allowing the complete system to be contained within one floor level. This then avoids entering the domain of other tenants within a shared building or space.

The systems are designed for automatic food waste collection medium sized applications. The operation is based on vacuum conveying. Systems consist of a Macerator Feeding Station (MFS), an Bvac Vacuum Unit and a Food Waste Tank, which includes discharge pumping unit. The volume of the holding tank is selected depending on the needed capacity of the system.

The number of Macerator Feeding Stations depends on the size of the galley. The locations of the MFS units in the galley area are placed close to where the food waste is generated. Then all the food waste can be quickly and easily fed in the MFS for conveying. The purpose of the MFS units is to grind the food waste into smaller pieces and form suitable slurry which can be conveyed through small dimension piping.

Vacuum is generated with a special Bvac Two Stage vacuum system. This guarantees strong and reliable conveying of food waste from the kitchen down to the holding tank. An advantage of the Vacuum Unit is that there are specialised pumps for air flow and liquid flow ensuring maximum efficiency and reliability of each pump.

The Bvac system is a modular system allowing one Vacuum Generation Unit (VU175) operating 6 Macerator Feeding Stations (MFS) to be paired with a range of Food Waste Holding Tanks from 5m3 to 1m3 or multiples of. This allows the selection of the tank to suit the constraints of the building i.e., mechanical holding, access and holding capacity.

Previous Experiences

Bvac and EVDS’ previous experience within the UK has been with vacuum drainage systems. Evac has been one of the world leaders in vacuum drainage systems since the 1970’s and has thousands of projects in both the marine and building industry.

In the UK we have completed many prestige projects such as Terminal 5 Heathrow, St Pancras International Station, Kings Cross Station, Blackfriars Station and major Supermarkets Tesco, Sainsbury’s and Waitrose.

Whilst Bvac’s experience with vacuum food waste systems has so far only been within the marine industry our experience in vacuum technology and marine installation transfers easily to the building industry. This was demonstrated when we introduced vacuum drainage systems to the UK construction industry in the 1990’s and today we have 150 installations.

In vacuum food waste systems people tend to focus on the macerator as it is the interface between the user and the system. However, whilst the macerator feeding station is an important part of the system it is not the most critical. The most critical is the vacuum technology and the know how that is used to transport the resulting sludge that the macerator produces.

Without this technology the sludge could not be conveyed from the extremities of the building to a central holding tank for processing. This part of the system needs careful planning and design to ensure a blockage free, uninterrupted service. It is this technology and expertise that Bvac can bring to your project.

EVDS, based in London, are the UK distributer of Bvac products. We can offer full after sales and “off the shelf” spare parts within 24 hours reducing any downtime or inconvenience. We are also able to offer full 24 hours a day service and back up plans plus a telephone helpline for an instant response.

Technical Information

Design Philosophy

The main consideration when designing a food waste system is to understand the operating philosophy of the kitchen and food preparation areas. One of the main factors is going to be in the way in which food is prepared.

  • Are they using semi-finished products in their kitchen, filleted meats and fish, pre- prepared “bought in” meals?
  • Or, will there be food waste produced from e.g. peeling the potatoes, cutting the fish heads and disposing those parts, Fresh prepared food using raw ingredients?

Operation “b” will produce more than twice as much waste as operations at “a”. We need to understand the operating philosophy of the Kitchens.

The second factor is the operator’s views on waste management and their clients /customers eating habits. Data collected by Evac from its marine partners’ has shown that on a Caribbean Holiday Cruise Liner, food waste can be as high as 3Kg per passenger per day. Whereas on a Scandinavian one or two day ferry cruise it can be as low as 200gms per passenger per day.

In this second example there is a complete waste management process plan in place, which covers everything from the type of food and raw produce purchased, its packaging, method of preparation and its dispose. These are all, elements that should be considered when designing a waste system.

The above chart also illustrates how a complete waste management process plan can drastically reduce food waste and in turn reduce capital equipment cost, operating costs, and disposal costs therefore any Food Waste Disposal System should be part of that waste management plan.

Food waste Storage Tank

One thing which will influence the size of the food waste storage tank is the frequency at which it needs to be emptied, and this is dictated by the size of the tanker which would be required to remove the waste. A road tanker can hold between 15,000 and 18,000 litres which equates to 14 - 15 tonnes per load although larger tankers are available depending of road conditions. Therefore the size of the storage tanks should be multiples of these figures plus a safety factor of 10%.

The waste in the storage tanks will require agitation on a regular basis to prevent the solids and the water from separating. If the solids are allowed to separate, then these will fall to the base of the tank, these can then clause blockages in the suction pipes and connections when the tank is emptied. Agitation is usually preformed by paddles in the tank and with a large tank more than one paddle would be required. Any maintenance, cleaning or repair to any one of the paddles would necessitate the complete shutdown of the system. The frequency at which the tank will need to be emptied is based on the total waste produced.

Vacuum Pipe Work

Vacuum pipe work will be a pressurised system with a minimum pressure rating of PN16 and Stainless Steel.

Vacuum pipe work should be protected against freezing with either insulation or electric trace heating in accordance with local practices and regulations.

Riser pipe work from the Macerator Feeding Stations will have a minimum outside diameter of 50mm.

The vacuum header and sub header pipe work from the connection with the Macerator Feeding Station riser to the Vacuum Generation Unit will have a maximum outside diameter of 75 mm.

The vacuum headers and sub-headers will be laid at a fall of 1:200. At 25 to 30 metre intervals, the header will rise up using two 45° elbow fittings to its original invert level, this will create a “saw tooth” profile to the pipe work. These points are known as “Transport or Reform Pockets”. These are an essential part of the system to enable the correct flow though the pipe work system. Transport and Reform Pockets may be repositioned to enable the vacuum pipes to pass under obstacles such as structural steel beams and service ducting.

The vacuum headers will run in the over head ceiling voids or in the ceiling voids below to Core 2 building riser where they will run vertical to the upper basement level. They will then run at high level to the vacuum generation unit and food waste holding tanks.

As the vacuum pipe work is not dependant on a fall, and transport pockets can be used to pass under or over obstacles, there is a large amount of design layout flexibility within the pipe network. This will allow for the exact pipe route to be designed or altered at a late stage in the building’s design process.

Brackets or clamps have to be used to secure the pipes. They must be at every 1.5m of piping in accordance to maker’s recommendation. Riser pipes from MFS shall be bracketed within 300mm of the base of the riser and 300mm either side of the bends at top of the riser.

All intermediate supports must be according to the pipe manufactures recommendation. All brackets shall have rubber inserts. Rodding eyes for pipe cleaning shall be in the end of every change of direction and so that every part of the piping is easy to clean.

Civil Engineering and Building Requirements

There is no major civil engineering works involved in the installation of the Evac food waste system. The vacuum units and holding tank may require plinths but this would be dependent on the floor structure and would be a decision for the structural engineer.

The vacuum pipe throughout is very flexible and can be routed over and around obstacles thus holes through beams and floor penetration will be kept to a minimum. However we would expect any core holes or floor penetrations to be provided by the main contractor.

Operation & Maintenance

Operation Principle

Food waste in the galley area is fed into the MFS macerator hopper and a start button is pushed. The macerator then starts to grind the food waste into smaller pieces. At the same time, a small amount of water is fed in the hopper to make sure that all the food is flushed down the macerator and becomes slurry.

When the MSF starts to run, generates vacuum in the pipeline. After vacuum reaches a certain set level located in the pump, an inlet pipe opens and the macerated food waste is flushed through the piping into the holding tank.

If the vacuum does not reach the set level in a certain time e.g. 10 seconds, an alarm is signalled (pipe leakage). If the vacuum does not decrease after the MFS line valve is opened in a certain time, another alarm is signalled (pipe blockage). The same thing happens if the vacuum reaches the high level vacuum sensor.

After that the system is ready for the next batch. When one MFS is in running mode, the other units are on stand-by if they are activated during running. Then, automatically, the next unit starts operation.

Discharge

When the level in the tank rises to the high level sensor and alarm is raised to signify that the tank requires emptying. When the level in the tanks gets down to low level, it opens the solenoid valve at the top of the tank for a set time. After that, the pump stops and the flushing valves are closed. Procedure continues until the level in the tank reduces to the low level switch. In the end of the flushing period, the water flushing system at the top of the tank is activated to flush the tank clean.

Manual discharge - On the main panel there is a start button which starts up the discharge locally. Procedure follows as above.

Tank Mixer System

Food waste inside the tank is kept mixed by means of a mixer. The mixing blades located inside the tank are installed on a mixer shaft and the shaft is then connected onto a gear motor at the top of the tank. The mixer is running based on a work pause control. Both the working timer and pause timer can be adjusted on the PLC.

Remote Controls and Control Signals

Remote discharge - There is a potential free relay for remote start-up for discharge. The whole tank is then pumped by normal programme. If the dewatering unit line is selected, the 3-way valve automatically turns to the discharge line direction.

Discharge not allowed - Potential free relay for signalling for discharging can be automatically programmed to send the collected food waste to a second holding tank. If the signal informs that the discharge is not allowed, the pumps will not start even if the level in the tank has risen to high level.

Tank full signal - If the tank level rises up to high level, an alarm is generated. A signal lamp on the main panel indicates a high level alarm. Every MFS station operation panel then has a blinking signal lamp indicating a high level. MFS units are then put out of order. Also, there is a potential free relay for remote BMS signalling.

General alarm - If any of the motor breakers are tripped, a general alarm is generated. There is one signal lamp on the main panel indicating a general alarm. This signal is available to MAS via potential free relay. If the general alarm is generated, a local operation signal lamp of the MFS will flash which indicates the MFS units are out of order.

Pipe leakage - When the set level of vacuum in the sensor is not reached in a certain time, this generates an alarm and is shown as ‘Pipe Leakage’ on the display.

Pipe blockage - When the set level of vacuum in the sensor does not decrease in conveying pipe work in a certain time, this generates an alarm and is shown as ‘Pipe Blockage’ on the display.

Auto/Manual - If the main panel is turned to manual operation, the MFS operations lights are flashing and units are out of order.

MFS Signals - If the macerator motor breaker trips, the operation signal light stays lit. If the start button on the MFS unit is pushed the collection mode will not be activated. If any of the MFS units are locally out of order this will be seen from the main control panel display.

MFS Unit Stand By - Only one MFS unit operates at a time. If another unit is activated, the start button light will flash and the unit will be on standby until the end of the operation period of the other unit in use. The unit on standby will then start its own period automatically.

Service, Maintenance & Training

The reliability and efficiency of your food waste vacuum system ultimately depends upon the maintenance system you have in place. We at EVDS can offer planned and reactive maintenance with a call out service enabling are customers to contact our duty technicians 24 hours a day 365 days a year, in the event of emergencies.

EVDS Limited can provide a bespoke maintenance program to suit you. Many of our customers take full advantage of this such as St Pancras International Railway Station and Kings Cross Railway station both having full maintenance contracts for their large vacuum systems. Our service and maintenance package is available ,this includes major six monthly services of equipment, service parts plus access to our telephone helpline and call out facility. Full product training to the client’s maintenance and operations staff will be given and is included with our package.

The Bvac food waste system can operate 24 hours a day, 365 days a year. The down time for maintenance is approximately 4 hours per service which would take place every six months. All training costs are included in our package.

Maintenance packages are available, these include major bi-annual service of equipment, service parts as well as access to our telephone helpline and call out facility.

Environmental Impact

The disposal of food waste into landfill sites is becoming increasingly unacceptable due to not only the financial costs but also the costs to the environment and its contribution to climate change. Greenhouse gas emissions associated with avoidable food and drink waste from all sectors in the UK are around 20 million tonnes of CO2 each year.

A solution to this problem is Anaerobic Digestion (AD), a process that recycles food waste to generate renewable energy in the form of bio-gas and returns a valuable bio-fertiliser to the land. This fully contained process avoids uncontrolled greenhouse gas emissions and pollution, generates clean green energy for the national grid and diverts food waste away from landfill. This British technology can deal with food waste in any form including solid, liquid and sludge. The AD process offers impeccable green credentials and is recognised by the UK Government, Defra and the NFU as well as being fully supported by environmental campaign group Friends of the Earth.

Not only is AD the green option it also fares better financially. Currently waste to landfill disposal can cost anywhere up £100 per tonne due to continuing yearly increases in landfill tax. However, industry leaders in food waste anaerobic digestion, Biogen, estimate costs of around £65 per tonne for transport and disposal to their AD Plants. Biogen are also able to offer discounted gate fees on long term contracts.

Power Consumption

The annual power consumption is dependent on the quantity of waste to be handled. Therefore the best way to illustrate this is per 1,000l of slurry or cubic metre of waste. Calculations, laboratory tests and live projects give us an average figure of 95kw per 1,000l or 1m³.

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