Aug 23, 2018

The Pains of Pigment

Prescreening & electrocoagulation for paint & pigment wastewater

Prescreening & electrocoagulation for paint & pigment wastewater

The paint and pigment industry is a large consumer of process and wash water to be used in various water-based paint pigment products. The water usage for this industry is estimated at 75 to 85 million gal per day, with the majority of this water coming from municipal or public supply, followed by well and surface water sources.

Only about 4% of the total water used in paint production is recycled worldwide. Nearly 70% of the total wastewater is untreated discharge with nearly 25% not discharged, but rather disposed of by evaporation or some other method.

Most of the wastewater generated in paint and pigment production facility operations results from cleaning the equipment used to manufacture water-based paints. The types of equipment most frequently cleaned are mixers, thinning tanks, and tinting and filling machines. Wastewater also is generated from cleaning the equipment used in the preparation of resins, solvent-based paints and other products as required.

Paint & Pigment Wastewater Composition

The wastewater composition generated by the paint and pigment industry tends to vary in concentrations of biological oxygen demand (BOD) or chemical oxygen demand (COD), suspended solids, toxic compounds such as volatile organic compounds (VOC) and color. The levels of BOD and COD can range from 500 ppm to 13, 000 ppm.

The discharge of such wastewater into the environment impedes light penetration, damages the quality of the receiving streams, and may be toxic to treatment processes, food chain organisms and aquatic life.

Reuse & Sustainability

Over the past few years, there has been several changes due to environmental regulations and consumer preference for paints containing lower VOCs, with no smell, and with reduced toxic heavy metal solvent coatings.

Sustainability efforts will continue to focus on opportunities to reuse the process water and wash water in applications such as cooling tower water or process water for paint and pigment production.

Waste minimalization is making significant inroads into paint and pigment manufacturing facilities. Because equipment washing is the largest source of wastewater production in the industry, utilization of a sustainable wastewater treatment reuse solution, such as the a specialized electrocoagulation (ECG) system, can enable water reuse. This water could be utilized for cooling towers or other ongoing process water treatment requirements in the facility. This process could result in potential savings of more than 40% over previous water and solids disposal costs.

As companies in this industry move toward pursuing sustainability goals to reduce operational costs and comply with increasingly stricter regulations, it is becoming apparent that water reuse is one of the key components of these initiatives.

Paint and pigment companies often produce wastewater containing elevated levels of suspended solids and color from their operations, in addition to non-biodegradable contaminants. Based on the levels of constituent contaminants discharged, the municipal wastewater disposal surcharge costs for the paint manufacturer may rise. Reusing this water can provide a significant return on investment for paint and pigment producers, not only through the removal of these wastewater surcharges, but also through the reduction of the cost to purchase freshwater.

Genesis Water Technologies specialized ECG wastewater treatment solutions demonstrate value in installations in paint and pigment industry water reuse applications by eliminating or reducing chemical costs and reducing sludge disposal costs and consumable expenses for secondary and tertiary treatment equipment.

Future Trends

Water reuse and sustainability will continue to be important goals for environmental pollution prevention or reduction practices in the paint and pigment industry.

The paint and pigment industry will continue to choose and utilize advanced innovative water treatment solutions to reduce not only its operating costs, but also its water footprint and ecological impact from wastewater discharge and solids sludge generation on the surrounding ecosystem.

Wastewater treatment process optimization will continue to be a key focal point for paint and pigment companies as the costs of wastewater disposal and freshwater consumption continue to escalate due to issues involving water scarcity.

An increasingly growing and progressively affluent global population and its demands on global water resources will necessitate higher water costs and stricter regulations. This is propelling paint and pigment companies and their discharging municipalities to re-evaluate their practices and push toward a more sustainable future.

Optimizing more efficient methods coupled with advanced treatment solutions to treat and reuse wastewater and process water will remain one of the most important points of paint and pigment manufacturing companies around the world.

Solving Sludge Buildup

A large paint and pigment company specializing in organic paints and pigment coating for cars and commercial applications wanted to reduce its operating and discharge costs to meet stricter discharge standards. The company had been using chemical coagulants and flocculants; however, this approach has generated substantial sludge volumes and discharge costs. Therefore, it sought a sustainable solution that could meet discharge requirements while reducing operating and sludge discharge costs. The initial COD levels prior to treatment were reaching 12,040 mg/L composed mainly of color and organic constituents.

Prescreening Paints & Pigment

GWT, with its local partner, designed and provided a solution to effectively handle its water streams.

The raw effluent was prescreened and pumped from a primary holding tank to remove coarse organic solids. This prescreened influent was sent to a GWT specialized ECG system, which was followed by secondary clarification via a settling clarification using GWT Zeoturb flocculant medium.

Tertiary treatment included post micron-filtration to remove any remaining coagulated color and particulates in the water.

Benefits & Results

Ultimately, this created a 70% reduction in discharge costs. Additional operating cost savings resulted from the reduction of fresh water consumption from cooling and cleaning water usage. The water was reused for cooling tower water treatment and cleaning and wash water applications in the facility.

Discharge compliance will be maintained in the clients operation with a reduction in sludge disposal costs over previous treatment approach, which increased the client’s return on investment.

The results after treatment were reported by a third-party laboratory analysis to be 406 mg/L, a reduction of almost 97% in this application.

About the author

Nick Nicholas is technical sales manager for Genesis Water Technologies. Nicholas can be reached at [email protected]

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