Water/Wastewater / Environmental Health & Safety / Water/steam

Conservation: Water Wins Wider Attention

Chemical makers strive to cut consumption and improve treatment

By Seán Ottewell, Editor at Large

A combination of tougher regulations and the need to manufacture in water-stressed parts of the world is spurring chemical companies to focus as never before on their water usage strategies. One effect of this is that water optimization technologies originally developed for the power industry increasingly are gaining traction in the chemical industry. At the same time, chemical manufacturers such as Bayer, BP and Dow are developing their own, sometimes nonconventional, approaches.

GE Power & Water, for one, is finding growing interest outside the utility industry for its technology — vertical-tube falling-film brine concentrators and evaporators (Figure 1) that can recycle wastewater into a high purity distillate suitable for boiler and cooling tower makeup, flue-gas desulfurization blowdown, NOx control and process use. According to the Trevose, Pa., firm, 15 to 20 years ago, 80 to 90% of demand for this kind of technology came from the power sector. Today, that figure is around 10% as demand rises in non-conventional oil and gas development, chemicals and other sectors.


“We’ve seen increasing demand from the chemical sector, particularly in the face of regulatory changes covering water use and wastewater discharge. Demand is strongest from companies located in areas where there is high population density and water stress — so, for example, much of the current demand is from companies in India and China in the chemical processing and coal-to-chemicals industries,” says Bill Heins, general manager, thermal systems — water and process technologies, GE.

He cites the example of a new Lanxess chemicals and intermediates plant in India. That site also uses GE’s zero-liquid-discharge crystallizer technology to reduce the brine concentrate to a dry solid.

The increasing popularity of evaporation for wastewater treatment is a sure sign of changing times, Heins believes. With certain notable exceptions such as steam-assisted gravity drainage heavy oil recovery, you typically wouldn’t put in an evaporation system solely for economic reasons, he explains.

“Reverse osmosis (RO) is less expensive per m3 of water treated, unless you have a highly saline, contaminated wastewater stream where RO is not technically viable. In the chemical industry, we are typically seeing waste streams from processes that are very hard to treat due to highly scaling constituents and high levels of organics and total dissolved solids. We can recover and recycle the water from these,” Heins notes.

An added advantage is that GE can treat mixed wastewater streams from different processes such as boiler blowdown, demineralizer regeneration waste, RO reject and chemical processes. Such integrated solutions often include wastewater preconcentration with membranes prior to thermal treatment.

The company currently is working with two clients to develop the next generation of thermal technology. It particularly is focusing on optimizing the integration of evaporation technology with different waste-treatment methods such as membrane separation, electrocoagulation, and physical-chemical treatment. “Our focus is on lowering their capital cost, reducing their power needs, maximizing reliability and reducing wastewater volumes as much as possible. Even a small change in water recovery results in a large impact in waste volume. For example, increasing from 98 to 99% water recovery at the tail end of the process means cutting the amount of water discharged in half. So from the user’s perspective, it means better water quality and better, more-efficient waste recovery,” notes Heins.

Another innovation is the introduction of a mobile evaporation unit. Originally designed for use by the unconventional gas industry, it now is finding wider applications — including with chemical companies that have waste ponds that need processing or that have filled more rapidly than expected due to high rainfall. GE is considering expanding its fleet in the face of growing demand.

MODULAR CONCEPT
Meanwhile, Bayer, Leverkusen, Germany, has developed a systematic and comprehensive process analysis called Resource Efficiency Check to uncover potential reductions in resource consumption, emissions and waste.

This modular concept enables the company to focus on specific issues relevant to production plants, for example raw materials’ use, packaging waste and water consumption. It also helps to identify possibilities for process-oriented optimization in boosting yields, recycling, utilizing byproducts and treating wastewater or waste air, so that these potential savings can be fully exploited.

First tested in pilot projects in 2011, the methodology now is being applied more widely to help Bayer companies optimize their water use. For example, Bayer CropScience currently is employing it on the synthesis processes involved in the production of trifloxystrobin, the active ingredient in the crop protection product Flint.

Bayer HealthCare also has used it to successfully finish the reorganization of rainwater management at its Bergkamen site in Germany. This facility produces intermediates, active ingredients and bulk pharmaceutical chemicals for steroid hormones via chemical and microbiological synthesis.

A clarifying and collecting tank, two pumping stations and a 1,500-m long subterranean tunnel have been installed at the site. The centerpiece of the project is the 12,500-m3 collecting tank. Water either can be pumped from here into the nearby river Lippe or used for operational purposes, mainly in refrigeration systems and air scrubbers.

Strategies such as this helped the company cut its overall water consumption by 20 million m3, or 6%, in 2013 — and also raised to 36 the number of Bayer sites where treated wastewater or steam-condensate recovery water is reused as process water.

In addition, last November Bayer’s main group board set a new water target within its resource efficiency program. This aims to establish a water management system at all sites in water-scarce areas by the end of 2017.

LESS WATER INTAKE
For its part, BP, London, reports a drop in freshwater withdrawal from 347 million m3 in 2012 to 312 million m3; last year. Refining, chemical and lubricant manufacture and storage terminals account for around 94% of this use.

Last year, the company began the systematic upgrading of wastewater treatment plants across the group. Now, 12 major sites — including the Gelsenkirchen and Lingen refineries in Germany, the Castellón refinery in Spain and the Rotterdam refinery in the Netherlands — are benefiting from new treatment plants. These systems were designed ahead of the introduction of new European Union refining standards due this year. New wastewater units also are in the works for the Whiting refinery in Indiana.

The growth of its manufacturing operations in water-stressed areas also has driven BP into developing new processes that have less impact on local fresh water supplies.

For example, the company’s Zhuhai 2 purified terephthalic acid (PTA) plant, Zhuhai City, China, which started operations in 2008, today generates 75% fewer water discharges, 65% fewer GHG emissions and 95% less solid waste than a similar plant equipped with conventional technologies.

The company says that proprietary, but undisclosed, recycling technology allows it to reuse much of its water on-site, reducing the amount of freshwater required for operations. Many of these modifications were made during a 20% capacity increase that was carried out in 2012; elements of this approach are being introduced at other facilities around the world.

One such facility is JBF Industries’ 1.25-million mt/y PTA unit currently under construction in Mangalore, India, that’s slated for commissioning by the end of 2014. The Mumbai, India, firm cites the BP process’s water and energy optimization technologies as key to its decision to license the process.

Meanwhile, BP itself currently is building a larger facility at Zhuhai. This plant, scheduled for 2014 startup, will be the first to incorporate the newest generation of its PTA technology — leading to further gains in efficiency and environmental performance, says the company.

NOVEL WASTEWATER TREATMENT
For Dow Chemical, Midland, Mich., constructing wetlands to treat wastewater at its Seadrift, Texas, plant has brought benefits in excess of $200 million so far.

Seadrift is a large complex containing several manufacturing units involved in the production of plastic resins and other organic chemicals. Originally, wastewater from the facility and storm water captured in containment areas were routed through a system consisting of primary (anaerobic/aerobic biological) treatment, secondary treatment and a shallow tertiary pond. The tertiary pond, covering approximately 267 acres with water depth ranging from 1 to 4 ft, operated as a solar stabilization pond with no active mixing.

However, lower organic loads and long retention time within the aerobic section and tertiary pond resulted in ideal conditions for phytoplankton and their floating algae blooms to thrive. This, in turn, caused the plant to exceed its 40-mg/l discharge permit criterion for total suspended solids (TSS) and required extensive pH adjustments. Eventually, it became clear that the site needed to upgrade its wastewater treatment plant — at an estimated cost of about $40 million — if it was to meet TSS regulations.

Fortunately, an engineer’s ingenuity and the willingness of site and business leadership to consider alternatives resulted in a very different solution: constructing wetlands for water treatment.

“The pioneering engineer based at the site, Mike Uhl, introduced the novel approach from projects he had seen previously outside of Dow,” notes Mark Weick, director, sustainability programs and enterprise risk management. “At the time, green infrastructure was not a commonly considered approach and took some convincing among peers. Uhl proposed the alternat[iv]e plan to leadership and found a champion who supported pursuing the idea for consideration — a key part of the plan’s success.”

A one-year pilot-scale constructed wetland project was completed successfully and later implemented on a full scale in roughly 18 months (Figure 2). It remains in full operation today and not only allows the facility to meet all discharge requirements for TSS but also has eliminated algal bloom issues and the need to adjust the pH of wastewater. Just as significantly, the initial capital cost was reduced from $40 million to $1.5 million, with additional savings in labor, maintenance and supplies.

“A financial analysis was completed in 2013 and showed the net present value of this project to be $200 million, significantly higher than the initial capital savings, while providing the added benefits of wildlife habitats and educational opportunities,” adds Weick.

Dow faced several challenges as it conceptualized this project, not least the lack of staff with the requisite skills or support from the culture necessary to bring this category of technology to scale.

“Given this lack of integration into technology capabilities, capital reviews or assessments, champions are required in today’s organizations to investigate and drive these non-traditional cost-advantaged solutions. ‘It’s hard to sell a swamp to an engineer,’ was a key message from the project team. Leadership emphasis and cultural change are needed more than further pilot projects,” notes Weick.

“Opportunities for green infrastructure and other, more sustainable solutions abound, and we are always looking into options for how to enhance the sustainability of our operations at sites around the world. Further implementations of engineered natural technologies are expected to increase total return on investment,” he concludes.

In another example of this approach, Dow is using trees to remediate dioxane in groundwater at its Terneuzen site in the Netherlands and elsewhere. (see: “Sustainability Gets the Spotlight").