Act before there’s not a drop to drink
Dow’s integrated production site at Terneuzen, the Netherlands, underscores how plants may rethink their water use. The facility is the current holder of the European Responsible Care Award from the European Chemical Industry Council (Cefic), Brussels, Belgium, for its innovative re-use of municipal wastewater. The local water company, Evides, uses water that is purified in a nearby biological wastewater treatment plant to produce demineralized water that’s then delivered to Dow Benelux for steam generation. Dow uses 60,000 m3 of water per day at Terneuzen, half of which comes from recycled process water and rain water — now around 7,500 m3 comes from the nearby community.
“Primarily we are looking at the water envelope and asking where we have the opportunity to minimize water consumption at all our sites while maximizing its recycle and reuse,” notes Gená Leathers, global technology leader — water, wastewater, landfill, at Dow’s Environmental Technology Center in Edina, Minn. “This project is an excellent example of us partnering with the local community to overcome the diminishing availability of water. We are currently working on a similar project with the community and other local industries near a site in Canada,” she adds.
The point here is that Dow now is considering water use right at the start of the design phase for projects for both grassroots and existing sites, so it can engineer in the most appropriate treatment strategies right from the outset.
Twenty years ago such a strategy would have been unheard of, but Leathers is confident about the way ahead. “There’s no doubt that this requires a mind shift, a cultural change. And we are learning all the time. Also, we are finding that the folks in engineering and design are very receptive to these ideas and keep them very much in mind while doing the evaluations,” she concludes.
This move ties in with a broader commitment the company has made to set the standard for sustainable water use and management through the application of innovative chemistry, technologies and business models.Worth its salt
One abundant but underutilized source of water is the sea. So, it’s little wonder that interest in desalination plants and technologies is strong.
As sources of high quality water for chemical processing become increasingly scarce, Dow, for one, is targeting desalination, both of seawater and brackish water (as well as water reuse applications and small, distributed systems for local use).
“In general, the cost of desalinated water has fallen dramatically — by more than half — in the last 15 years,” says Chuck Martz, global marketing director for Dow Water Solutions in Edina. “So demand for the reverse osmosis (RO) and nanofiltration (NF) membranes we manufacture for use in desalination is growing rapidly on a global basis. Desalination will have double-digit growth for the foreseeable future,” he adds.
Reflecting this heady prospect, in mid-June Dow announced an $88-million expansion at the Edina facility — the third investment there in eight years. Part will go for an expanded manufacturing area to boost output of advanced technologies such as RO and NF membranes and for automated production of 16-in.-diameter elements.
Dow expects to launch these larger elements at the Aquatech Amsterdam exhibition that starts at the end of September. “These are important because they cut the capital cost of a desalination system by 10–20%,” notes Martz.
Figure 1. This module forms the heart of new reverse osmosis elements.
Dow, on July 10, announced plans to build a $15-million Water Technology Development Center at its Tarragona facility by the Mediterranean Sea in Spain. Due to open next year and employ 25 researchers, it will have ready access to seawater and will be able to obtain brackish water, industrial wastewater and treated river water. The idea is that the center will help Dow understand how to achieve the best performance and lowest operating costs for treating different water types.
At the same time, the company has launched two new seawater RO elements (Figure 1).
The first boasts better rejection of boron, a trace contaminant that causes a variety of different problems, not least in Israel where its presence in desalinated water has made artichokes go brown. The World Health Organization also warns against raised levels of boron in potable water.
The second targets energy use, which is the biggest cost associated with desalination.
Energy savings realized depend on temperature, water salinity, design flux, fouling tendency, efficiency of pumps and motors, and use and efficiency of energy recovery devices. In a typical seawater system, the savings are roughly 0.3 kWh/m3 and energy consumption of the membrane stage could be brought down from roughly 2-2.5 kWh/m3 to 1.7 to 2.2 kWh/m3. In selected scenarios (low temperature, higher fouling tendency, inefficient pumps, no energy recovery), the saving is more in the range of 0.6 kWh/m3. With an energy cost of five to 10 U.S. cents/m3, this is a savings of one to four U.S. cents/m3. “The trade-off is slightly elevated permeate salinity. In many cases the salinity will still be within WHO expectations.”
And this highlights the desalination crux: “We are always trying to make the membrane more permeable in RO, but at the same time reject unwanted salts. So we are always looking for new chemistries. What industry wants is to meet the required specification, whether for potable water or ultrapure water. Once you can meet this, you then look at the cost of water production. So we work with companies such as Siemens, Veolia and many others to try and find solutions that optimize the cost of the water coming out of the system,” says Martz.Targeting industry
Pall, East Hills, N.Y., also sees industrial water treatment as a growing business. “In the last year we have set up a dedicated engineering applications group within our industrial water section. So we’re definitely gearing up for it,” says Thomas H Wines, senior marketing manager.
Figure 2. Combining microfiltration and reverse osmosis, this system can cope with significant variations in feedwater. Source: Pall Corp.
In particular, Wines points to growing interest in the company’s Integrated Membrane System (IMS) technology (Figure 2). “The point here is that a technology originally developed for municipal drinking water has moved into the industrial water sector and is a growing business,” he explains.
Origin Energy, one of the leading energy providers in Australia, New Zealand and the Pacific, is an early IMS beneficiary. One of the company’s main products, coal seam methane (CSM), is expected to produce 90% of the total gas required in Queensland, Australia. To recover the gas, however, requires water to be pumped from the coal seams to reduce the pressure and allow large volumes of gas to flow. This water traditionally has been difficult to treat with membrane technologies because of its wide variety of contaminants. To add to the challenge, the company’s Spring Gully development near Roma in central Queensland is in a drought-affected region of Australia where water management is especially critical.
So Pall was asked to develop and trial an IMS that utilizes microfiltration (MF) and RO systems specially designed to deal with CSM water. Following success with this, Origin early in 2007 contracted Pall to supply a full-scale IMS facility at Spring Gully.
This IMS comprises four MF racks, each containing 56 0.1-µ Microza modules, an RO system, a pre-strainer, chemical dosing, compressed air systems, plus interconnecting pipework and motor control centers.
Although implementation was complicated by the remoteness of the Spring Gully site and the high degree of process customization, the IMS facility was successfully brought online in December 2007. The current production capacity is nine million liters per day (MLD) day, and the IMS can be expanded to support up to 15 MLD.
IMS has already garnered a lot of interest from other sites, both in Australia and North America.
“Note that another new application of this technology is in ethanol production, where lots of water is used to generate the steam required in the distillation process. We are breaking into this market now. It’s not a standard technology on all new ethanol plants, but it is the future technology so we are leading the way here,” adds Wines.
Interest is also burgeoning in the company’s ceramic-based MF units. These allow smaller flocs of bacteria to circulate, resulting is a very clean permeate and thus no need for a clarifying stage.Singapore success
Meanwhile, Siemens, Erlangen, Germany, which owns USFilter, in June received a $3-million grant from Singapore’s Environment and Water Industry Development Council (EWI) to develop innovative seawater desalination technology that relies on an electric field to remove salts. The aim is to reduce energy consumption by 50% compared with existing desalination methods. Siemens will use the funding for work at the company’s global R&D center in Singapore.
The process integrates electrodialysis, ion exchange softening and a final desalting step that uses a novel continuous electrodeionization process to drive salt separation with minimum energy demand. EWI’s challenge required demonstration of energy consumption of 1.5 kWh/m3, which is about half of what has been achieved with the best available technology. Operating desalination plants typically consume as much as 10 kWh/m3.
Siemens is also moving ahead on the commercial front. In March, it acquired the Chemitreat Group, Singapore, which had sales of more than $40 million last year, employs 240 people and provides water-treatment technologies and services in Singapore, Thailand, Malaysia, the Philippines and China.Cooling water challenges
At many plants, water plays a key role in cooling process streams. Cooling systems routinely are pushed to capacity. When stressed to their technical limits, upset conditions result in expensive operational problems such as scale, corrosion and fouling.
This has offered a growing opportunity to Nalco, Naperville, Ill., for its 3D Trasar (Figure 3). This technology measures key system parameters, detects upsets, takes appropriate corrective action and communicates with system users. According to the company, it provides reliability under high stress operating conditions and delivers the lowest possible total cost of operation (TCO) for cooling operations.
Figure 3. Before and after shots show dramatic improvement provided by scale control program. Source: Nalco Co.
And the numbers back up the claims. For example, the operator of a petrochemical plant in France was struggling to overcome scale and corrosion problems. Implementation of a 3D Trasar program led to use of a more effective corrosion inhibitor and a better control strategy. Visual inspections of heat exchangers and corrosion coupons verified significant improvement: an overall reduction of $206,000/yr. in TCO, including $63,000/yr. in heat exchanger cleaning, retubing and repair costs.
Another example is a Gulf Coast chemical plant where calcium phosphate fouling in one critical heat exchanger led to a $250,000 revenue loss. After implementing a 3D Trasar program, total inorganic phosphate was reduced by 50% to 10 ppm from 20 ppm and the critical heat exchanger operated at near-design cleanliness for 11 months. This led to record production runs for the unit through the hottest months of the summer — boosting revenue by more than $250,000 — and an elimination of semi-annual cleanings.
In recognition of these and other successes, the White House honored 3D Trasar technology with a 2008 Presidential Green Chemistry Challenge Award.Continued role for chemicals
Meanwhile, the traditional industrial-water treatment-chemicals market remains healthy. Palo Alto, Calif. revenues should grow from $2.3 billion in 2006 to $2.8 billion in 2013, according to the most recent market analysis in North America by Frost & Sullivan (F&S).
“The Clean Water Act gave the Environmental Protection Agency (EPA) the authority to implement pollution control programs by setting strict standards for wastewater discharged from industries,” says K. Deepan Kannan, F&S research analyst. “This is expected to minimize the effect of effluent discharge on the environment, while increasing the need for industrial water treatment chemicals.”
The report notes that, despite the availability of more advanced technologies, water treatment chemicals stand out for their cost efficiency.
This conclusion undoubtedly resonates with suppliers, which include some of the largest chemical companies.
BASF Specialty Chemicals, Ludwigshafen, Germany, offers a range of treatment chemicals including complexing agents, defoamers and biocides. For instance, its Trilon B complexing agents can remove deposits of calcium sulphate, calcium carbonate, calcium phosphate and other sparingly soluble salts that form scale in boilers, evaporators, heat exchangers and filters.
Meanwhile, DuPont, Wilmington, Del., provides a chemical to rehabilitate the flow efficiency of water wells. Typically, efficiency decreases with time. According to the company, its glycolic acid is being used extensively in such wells because it can remove hard water scale caused by calcium, magnesium and manganese salts, along with various iron deposits and polysaccharide deposits. And, compared to rival treatments, it reportedly boasts low corrosion to metal parts in wells, low toxicity and odor and ease of handling.