A Cleaner Exit: The Case for Direct Discharge

Overtreating Clean Water 

For many industrial facilities, non-contact cooling tower blowdown (or clean water that’s been used to help cool equipment in industrial systems) is routinely sent to municipal wastewater treatment plants for disposal. But this practice often results in unnecessary costs and inefficiencies, specifically because the water being treated is already clean. 

“Most cooling blowdown is cleaner than the wastewater plants designed to treat it.”

Non-contact cooling tower blowdown typically utilizes potable water as an input and isn’t exposed to process contamination. It lacks organic material, nutrients, or solids that wastewater treatment plants are built to remove. Publicly Owned Treatment Works (POTW) depend on those contaminants to maintain process treatment efficiency. 

Direct discharge is a lesser-used but highly effective disposal method for non-contact cooling tower blowdown. It offers compelling environmental and economical advantages. With the right planning and risk mitigation, it can benefit both industry and public infrastructure.

A Cleaner, Smarter, More Cost-Effective Path

Direct discharge involves sending blowdown water directly into a receiving body of water — such as a river or lake — under a state-issued permit under the National Pollutant Discharge Elimination System (NPDES). This permitting approach maintains rigorous monitoring and water quality provisions which ensure that the permitted discharge does not adversely degrade water quality in the receiving water.

Since treated blowdown water doesn’t typically contain the common contaminants that exacerbate treatment cost and environmental concern, the main consideration is often temperature. However, with proper engineering controls and more efficient cooling systems, discharge temperature can be maintained at or below ambient temperature in the receiving water.

The Primary Advantages

1. Cost efficiency. Direct discharge eliminates surcharges tied to metrics that don’t apply to clean water. This also avoids wastewater treatment volumetric rates, which are structured to cover the costs of eliminating contaminants not present in non-contact cooling tower blowdown.
2. System alignment. Avoids straining wastewater plants designed for dirty water, which operate less efficiently when receiving clean influent.
3. Environmental benefit. Reduces demand on municipal systems while returning usable water back into the environment, often keeping the benefits of clean water flows more localized to the point of use.

De-Risking Direct Discharge

The perceived regulatory burden of direct discharge can deter some operators. But with early engagement, a clear permitting strategy, and strong technical design, this risk can be managed. De-risking strategies include: 

• Regulatory alignment. Work proactively with state agencies to secure NPDES permits. Agencies are often more collaborative than assumed, especially when environmental benefits are clear. 
• Advanced treatment and monitoring. Leverage technologies like pH adjustment, chlorination, UV disinfection, and real-time sensors and sample points (pH, turbidity, heavy metals, PFAS, etc.).
• Environmental safeguards. Conduct ecological risk assessments and mixing zone analysis to ensure clean water discharge meets the need of the receiving water.
• Stakeholder transparency. Share data openly with regulators, communities, and NGOs, and invest in Corporate Responsibility (CSR) initiatives. Develop rapid response plans and regularly train staff on handling reputational risks.
• Legal and financial protections. Secure appropriate liability coverage and include indemnification clauses in third-party contracts.

For certain facilities not ready to manage a permit directly, there is an option to partner with third-party operators who hold a discharge permit. While this structure offers many of the same benefits without the compliance burden, it’s only available in certain states. 

Ultimately, by integrating advanced treatment, rigorous monitoring, stakeholder engagement, and proactive risk management, the direct discharge option can be de-risked significantly. The key aims are to exceed regulatory requirements, ensure transparency, and demonstrate environmental stewardship to protect both ecosystems and corporate reputation.