Recognizing Toxic Chemical Discharges in Wastewater Systems

Illicit chemical discharges can create serious problems for municipal wastewater treatment facilities, particularly smaller rural systems with limited treatment capacity.

Chemicals associated with illegal drug manufacturing can enter wastewater collection systems through sewer connections, septic discharges, RV dump stations, or other unauthorized disposal points.

When these concentrated chemical loads reach a treatment plant, they may severely inhibit or destroy the microbial populations responsible for biological wastewater treatment.

How Toxic Chemical Loads Affect Wastewater Treatment

Both lagoon systems and mechanical wastewater treatment plants can experience biological failure following a significant toxic discharge.

Potential impacts include:

• Sudden loss of biological activity
• Reduced BOD removal
• Loss of nitrification
• Elevated ammonia concentrations
• Failure to meet discharge permit limits
• Significant changes in wastewater color
• Strong or unusual odors
• Extended biological recovery times

A rapid and unexplained decline in treatment performance may indicate that a toxic substance has entered the wastewater system.

Warning Signs of a Biological Treatment Upset

One of the clearest indicators of a serious toxic event is a sudden loss of microbial activity.

Operators may notice that treatment performance declines even though normal influent loading and operating conditions have not changed.

Other potential signs include:

• Unexpected changes in lagoon or basin color
• Increased odors
• Poor solids settling
• Reduced oxygen demand from the biomass
• Rising effluent BOD or ammonia
• Loss of nitrification
• Failure to meet discharge requirements

Color changes alone should not be used to identify a specific contaminant, but they can provide an early indication that biological conditions within the system have changed.

Inspect Collection System Debris Carefully

Operators may also notice unusual materials entering bar screens, lift stations, or headworks.

Suspicious debris associated with an unknown discharge should be documented and handled carefully, particularly when accompanied by a sudden biological upset.

If wastewater personnel believe an illegal chemical discharge may have occurred, they should follow facility safety procedures and contact the appropriate local authorities.

Workers should avoid direct contact with unknown chemicals or contaminated materials.

Monitor RV Dump Stations and Septic Discharges

Facilities that accept wastewater from RV dump stations, septic haulers, or other hauled-waste sources may face additional risk from unknown or highly concentrated waste streams.

Wastewater utilities can reduce risk by maintaining clear discharge policies and monitoring incoming waste.

Useful practices may include:

• Documenting hauled-waste sources
• Monitoring unusual discharges
• Restricting unauthorized access
• Inspecting RV and septic receiving areas
• Establishing pretreatment or acceptance requirements
• Training staff to recognize unusual wastewater conditions

Early identification of an abnormal discharge can help operators respond before the contaminant affects the entire treatment process.

Case Study: Restoring a Wyoming Lagoon After a Toxic Discharge

A municipal lagoon system in Wyoming experienced a severe biological upset associated with a suspected illegal chemical discharge.

The treatment system lost biological activity and required rapid intervention to restore wastewater processing.

Operators implemented a recovery program using potassium permanganate and BioLynceus® ProBiotic Scrubber®.

Potassium permanganate was applied at approximately 9.3 pounds per acre-foot of water, while ProBiotic Scrubber® was applied at approximately 0.2 gallons per acre-foot. Both treatments were applied for three days.

According to the case study, the lagoon recovered biological treatment performance in less than 10 days.

The treatment program also helped prevent the biological upset from progressing into the facility's two additional lagoon cells.

The facility was able to maintain compliance with its WYPDES discharge permit during the recovery process.

Restoring Wastewater Biology After Toxic Shock

When a toxic discharge damages a wastewater treatment system, restoring a healthy microbial population as quickly as possible can help shorten recovery time.

A recovery strategy may include:

• Identifying and stopping the contaminant source
• Restoring adequate dissolved oxygen
• Monitoring pH, ammonia, BOD, and other treatment parameters
• Reestablishing beneficial microbial populations
• Using bioaugmentation to rebuild biomass
• Closely monitoring effluent quality during recovery

The appropriate treatment strategy depends on the type of system, severity of the biological upset, wastewater chemistry, and operating conditions.

Bioaugmentation for Wastewater Recovery

BioLynceus® biological products can be used as part of a wastewater bioaugmentation and plant-restart strategy following toxic loading events.

Introducing concentrated microbial populations can help rebuild biological activity and support the recovery of processes such as:

• BOD removal
• Nitrification
• Organic matter degradation
• Biomass development
• Overall wastewater treatment performance

Rapid response and careful monitoring are important when recovering from a significant toxic discharge.

© Rick Allen, BioLynceus® 2012–2013
Mark Court, Circuit Rider, WARWS