Water recycling is a necessity for most stone companies but how do you choose which system to install? NSS talks to suppliers of recycling systems and to some of their customers.

Since James Turton’s New Stone Age in Keighley, Yorkshire, started representing OMEC in 2004, the Italian company’s water recycling systems have become the solution of choice to many in the stone processing industry.

What customers particularly like is that they do not have to compromise because they each receive a bespoke system based on their needs now and into the future.

New Stone Age will advise on and design a complete water management system, even though OMEC does not normally install the pipework in the buildings. The technical support from both OMEC and New Stone Age is widely praised by customers who have installed the systems.

OMEC uses a filter press that is fully enclosed, as are the silos and their associated pumps and controls, which means they can be heated in winter to stop them freezing up. It also keeps everything tidy, rather than having wires and pipes trailing around.

Stainless steel pipework and galvanised structures are used to combat rusting, and redundancy is built in on critical components such as sump pumps and clean water pumps, so there is always one in reserve in case of failure. The pumps are used in rotation, a week at a time, to ensure the one in reserve works if it is needed.

The level of automation of OMEC systems can also be varied according to the customer’s requirements, ranging from manual control up to the automatic addition of flocculents and pressing that is determined by a set number per day or by the system’s controls based on the amount of contaminant in the water.

Technicians from OMEC even arrive with a full toolbox, so the customer does not need to give much assistance during installation (apart from supplying a crane).

Fulvio Allegri from OMEC says: “Although OMEC worked since many years with other countries around the world, the United Kingdom was a completely new market for us when we were contacted by James Turton in 2004 and we have to thank New Stone Age for having introduced our products to this market.

“In recent years we have witnessed the strong development of New Stone Age due to the commitment and professionalism of James Turton. We think that at this moment OMEC is the point of reference for water management in UK for the stone industry.”

Five OMEC systems have been installed in the past few months at Cumbrian Stone in Penrith, Ian Lowes Stonemasonry in Wigton, Cumbria, Fairhurst Stone in Carnforth, Lancashire, A D Calvert in Leyburn, and Meister Masonry in Painswick, Gloucestershire. For Fairhurst Stone and Meister, the systems are for new factories, while for the other two sites the new plants are upgrading the water management at existing factories.

The variety of the systems installed shows the versatility of the OMEC solution.

At Cumbrian Stone, the system comprises of an OMD 30 (30m3) water cleaning silo, which has a diameter of 2.25m and is 10m high. It is fed by two sump pumps (alternately working and on standby), each capable of delivering 2,200 L/min, which ensures a good pause time to let the mud settle correctly in the silo.

There is a 1,000-litre flocculent tank that automatically doses when required and uses £5-10 worth of flocculent a week.

An OMF 610 filterpress has ten 600 x 600mm plates. It is fed by a Yamada pneumatic piston pump and is fully enclosed on a steel platform, all supplied by OMEC.

The OMF 610 is an automatic model performing a predetermined number of presses a day (based on the size of the mud discharge container / skip). If the silo is emptied of mud, the press will stop and wait for the operator to restart the cycles.

There is an OMT 20 (20m³) clean water storage silo 2.25m dia x 8m high which supplies clean water to the factory using pumps supplied by OMEC.

Again, there are two pumps (one working and one on standby) each capable of delivering 1,200 L/min at 2.8 Bar, which ensures good water flow and pressure to the factory’s BM primary saws and GMM Euro secondaries. The pressure is important as each machine normally requires at least 2 Bar to ensure its safety pressure switches are working.

New Stone Age / OMEC also supplied a preformed stainless steel well, which makes it easier to form a well in the ground without using shuttering or precast concrete rings.

Currently, Cumbrian Stone requires 600L/min of water for its machines but wanted to be sure its water treatment plant could cope with future expansion, having outgrown its previous, manually operated filter press system installed when the business started seven years ago.

Mark Johnstone at Cumbrian Stone says he did look at alternative systems but was most impressed by the OMEC offer. He told NSS: “We have dealt with New Stone Age for quite a while and they have always been good to work with. We like the style of the OMEC system – everything is enclosed.

“James [Turton] came and did a survey in preparation for giving us a full quote, then we had to get the civils done. Then they came and installed it in five working days.

“We had to have it because we were at a stage where we couldn’t put another saw in without a new filtration system. It’s one of those investments that’s not going to increase productivity but you just have to find the money to do it.”

At Fairhurst Stone the system has only just been installed in a new, bigger factory at Longcliffe, near Settle, with a new paving line, wire saws and Pedrinis.

Fairhurst Stone has a different water recycling system at its factory in Carnforth but chose the New Stone Age OMEC version for the new factory because, says Edward Fairhurst, “everything is more robust; more heavy duty”.

The system comprises an OMD 60 (60m³) water cleaning silo that has a 3m dia and is 12m high, fed by three sump pumps (two working at a time and one on standby). The two working pumps deliver 4,400 L/min. A 1,000 litre flocculent tank automatically doses when required and includes automatic flocculent preparation, mixing the flocculent powder when required. It uses £15-30 worth of flocculant a week.

The OMF 814 filterpress has fourteen 800 x 800mm plates fed by a Pemo impellor pump. Its stainless steel impellor has been specially designed by OMEC to reduce wear caused by the abrasive nature of the stone.

The fully enclosed filterpress is an automatically regulating model that analyses the consistency of the mud being pressed and determines when the next press needs to be made, although the number of presses is limited to the capacity of the mud discharge skip so it does not spill.

An OMT 35 clean water storage silo 2.25m dia x 11.5m high has two pumps, used one at a time to supply the factory with 2,500 L/min at 2.8 Bar.

The silos are painted green to match the building, as the factory is in a National Park.

Ian Lowes Stonemasonry has a smaller, Kompact system delivering 500 L/min to the factory that currently requires 300 L/min. The OMD 10 water cleaning silo has a diameter of 2.25m and is 5.5m high. It is fed by two sump pumps, each delivering 600 L/min. The 300-litre flocculent tank automatically doses when required, using £3-5 worth of flocculent a week.

The system has an automatic OMF 604 filterpress performing a predetermined number of presses. It has four 600 x 600mm plates fed by a Yamada pneumatic piston pump. New Stone Age also supplied a preformed stainless steel well.

A D Calvert and Meister Masonry have systems supplying 1,600 L/min of cleaned water and clearing 12m³ of mud per day. They use OMD 30 water cleaning silos fed by two sump pumps, each delivering 2,200 L/min. A 1,000 litre flocculent tank automatically doses when required in each case and there are OMF 814 Filterpresses with fourteen 800 x 800mm plates fed by Pemo impellor pumps. The filterpresses are fully automatic, analysing the consistency of the mud being pressed to determine when the next press is necessary. There is an OMT 25 clean water storage silo.

Wherever stone companies buy their recycling systems, what they want from the supplier is the minimum amount of disruption to production and a system that can be relied upon. Waters Group says that is what it offers with the Lindo from Martini Aeroimpianti. And Andy Goodwin of Caterham Marble & Granite in Stoke on Trent confirms that Waters is as good as its word.

Caterham Marble & Granite already had a Turrini Claudio water recycling system in its factory supplying water to a range of machinery including six Intermac CNC workcentres, but when it planned on replacing one of the workcentres and adding another Breton saw, it needed extra water recycling capacity.

Andy Goodwin contacted several suppliers and was impressed by the speed at which Waters Group came back with the information he wanted. He had bought tooling and consumables from Waters before, so the company was not an unknown entity to him and he felt comfortable dealing with them.

Caterham Marble & Granite chose the Lindo Compact 400 (it delivers 400 L/min and there is also a 600 L/min version), which has a footprint of just 2.2m x 1.9m and is only 3m high.

It did not need new foundations and was delivered and connected up by Waters with minimal disruption.

Andy Goodwin had been surprised to learn that the Lindo would not need flocculents for the granite worktops and marble fireplaces Caterham makes. With some stones – sandstones, for example – some customers do find it helps to add flocculents to encourage the solids in suspension in the water to settle, but it is not necessary with most stones because the lamellar packs inside the silo minimise turbulence and allow the sludge to settle quickly.

“The water is clearer than it is with the Turrini Claudio, which relies more on flocculents,” says Andy Goodwin. “I’m pleased with the Lindo. I would definitely recommend it.”

And he was pleased with Waters. It was not only the speed and quality of information he received in response to his initial enquiry that impressed him but the fact that the level of service was maintained. “They have a good knowledge of the products and they have always answered any queries quickly.”

Before the unit was delivered, Caterham had to dig a pit to collect the dirty water, which it lined with a 2.5m length of 1m dia sewage pipe. A sludge pump delivers the dirty water into the silo of the Lindo and it is filtered into bags, rather than being squeezed in a press. Caterham also had to prepare the pipework to take the recycled water to the machines.

Then, when the Lindo was delivered, the Waters Group engineers simply connected the unit up, with installation already included in the price of less than £15,000.

Waters Group Ltd is a family business supplying the stone industry for more than 30 years. It has built up a wealth of knowledge in that time in all areas concerning stone processing, including water treatment, having supplied the products of Italian manufacturer Martini Aeroimpianti for more than 10 years.

Waters Group MD Nicola Waters says: “Customers may be starting from scratch or looking to add on to an existing system. Either way, we know what questions to ask to work out what our customers need and can quote swiftly and arrange delivery and set up to suit customers’ timescales.”

The standard version of the water treatment plant includes a range from 120 L/min up to 1,000 L/min, while larger units are available on request. With the standard plant comes the option of either a jumbo bagging system or a filter press. Either way, it is supplied in a complete package that includes all pumps and installation.

Another range of water treatment plant popular with stone processors comes from Turrini Claudio, which is supplied by both Accurite and Breton UK.

The range is extensive. There are systems with either bags or presses for supplying anything from 150 L/min of water to 5,000 L/min (a big system has just gone into Marble Building Products in Yorkshire), although most of the units currently being supplied in the UK are in the range of 250-800 L/min, as granite, marble and stone processors either decide they have to improve their water management for the sake of their machinery or because they are told to by Health & Safety Executive or Environment Agency inspectors.

Turrini Claudio systems recently installed have gone to Bellagio in Leamington Spa, Ivett & Read in Cambridge (pictured right), Yes Granite in Northamptonshire and Worcestershire Marble in Bewdley.

Plenty of companies understand that not having an appropriate water recycling system is likely to attract the attention of the health & safety and environment bodies and install systems before they receive a visit.

Often there is a need to increase recycling capacity as new machinery is added to a factory – and using cleaner water also means less maintenance and longer lasting tools.

Even so, it is difficult for most companies to identify any improvement to their bottom line as a result of investment in water management, which means the purchase of such systems is often made reluctantly because most companies would rather spend their money on machinery that will improve their productivity.

The highest expectation most companies have of their water recycling unit (apart from clean water) is to be able to put it in and forget about it.

Be aware of the threat of Legionnaire’s Disease

by Tony Mitchelmore of the Water Management Society.

Most water can be reused if the suspended solids produced by the various processes can be removed. Techniques for achieving this include:

a) Sedimentation – whereby the stone particles are allowed to settle, this process can be accelerated by the addition of flocculants, organic chemicals with long-chain molecules that neutralise the electrostatic charges on the solids, causing them to agglomerate to form larger particles that can separate more rapidly under gravity.

b) Filtration – wherein the spent water is passed through a bed containing filtration medium such as sand / anthracite. A low dose of flocculant may be required to improve the efficiency of the process.

c) Centrifugation – Passing the water through a centrifuge or hydro-cyclone spins out the solids as a slurry leaving a relatively clean water.

Because some of the stone processing procedures produce spray, bacterial growth in any recycled water should be strictly controlled, to avoid the proliferation of Legionella bacteria and minimise the risk of Legionnaire’s Disease.

The recirculating water should either be regularly dosed with biocides or continuously dosed with chlorine to achieve a constant low level, preferably using automated equipment.

Bacteria levels should also be regularly monitored. Legionella bacteria are widespread in the environment and will multiply to dangerous levels unless control measures are put in place.

www.wmsoc.org.uk

A scarce resource under pressure on many fronts

by Brian Pickworth, the Technical Manager of the Klargester Division of Kingspan and Chairman of the UK Rainwater Harvesting Association.

The natural stone industry is highly dependent on the copious supply of relatively cheap water, a resource already under substantial pressure in many parts of the UK.

According to recent Environment Agency studies, stresses on water supplies are predicted to intensify substantially in coming decades under the twin pressures of population growth and climate-change.

Apart from the particularly wet 2012, there has been ample experience of water shortages in recent years, where the typical UK pattern of light but regular rainfall has given way to prolonged dry spells broken by torrential downpours. The net effect of this is that, although annual average rainfalls remain largely unchanged, the heavier bursts of rain pose flood risks which need to be relieved. In the process, more water is lost to the sea and less can be retained for use.

These issues are well understood by Government and reflected in a variety of policies aimed at specialist sectors such as agriculture, which could potentially be hard-hit by future water shortages. The construction sector, too, is required to ensure that all new building projects are much more water efficient than the existing built environment.

One of the ways in which this is being achieved is by use of rainwater harvesting, a historical practice brought up-to-date by modern technology. These systems simply collect the water falling on the roof, filter and store it, then supply it automatically on demand to non-potable services such as toilet-flushing, clothes washing machines and irrigation. In the home, this accounts for around 50% of all water use.

Collected rainwater is also ideal for industrial processes such as stone-cutting, subject to H&S precautions being taken to guard against the accidental inhalation or ingestion of spray.

The amount of water that can be harvested simply derives from two main factors – the annual rainfall at the site concerned and the size and nature of the collection area. But as long as enough can be collected, more than 90% of water used on an industrial site could come from sources other than the mains.

Any industrial unit combining a large roof area with a high demand for non-potable water could find harvesting rainwater to supplement the mains supply an attractive, straightforward commercial proposition offering a short pay-back period on the relatively low capital investment.

Assuming the Environment Agency’s bleak predictions are even half-way correct, sectors such as the natural stone industry are bound eventually to come under regulatory and price pressures to reduce reliance on mains supplies of water or local abstraction. In Germany, domestic water already costs twice as much as in the UK and four times as much for industrial users.

Faced with this outlook, it would seem prudent for industries that rely heavily on water to be looking at ways to turn this threat into an opportunity. At the very least, a simple desktop feasibility study would be merited.

A factory with a roof area of 10,000m2 could expect to harvest around 5million litres of rainwater per year, even in the relatively dry South-East of England. If this could be harvested and used evenly throughout the year it would average 25,000-litres per working day. It sounds a lot but it would be consumed in less than an hour by a factory using 500 litres per minute.

A rainwater collection installation may well offer a quick payback period, even at today’s water prices, but it could not completely address the future water supply challenge. Nor would it help to resolve any effluent-related factors of the quantity and quality of the discharge, which may become a major issue as water-quality legislation starts to bite.

In an ideal world, businesses with water-dependent processes would want to be as independent of external suppliers and abstraction licences as possible. The most elegant way of achieving this in the natural stone sector is to re-use the water and top-up losses from the system using harvested rainwater. This would have the double benefit of eliminating a substantial proportion of the sewerage charge while ensuring that the quality of discharged water meets the requirements of environmental legislation.

Supported by the rainwater harvesting system manufacturers, the natural stone sector is particularly well-placed to consider the feasibility and cost-effectiveness of meeting its water needs this way. The technical challenges of meeting operational flow-rates is well within the competence of the rainwater harvesting industry, with most manufacturers also able to advise on the best way to treat and store water between re-uses.

A partnership for today, to help meet the water-supply challenges of tomorrow.

For further information see www.ukrha.org