Inorganic chloramines and chlorinated wastewater effluents: performance report

 

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Inorganic chloramines and chlorinated wastewater effluents were found to be toxic under the Canadian Environmental Protection Act, 1999 (CEPA 1999). This pollution prevention (P2) planning notice was selected as the instrument to respond to the requirements of CEPA 1999 for these toxic substances, with the recognition that these substances would be further addressed as part of a harmonized national approach to wastewater management. 

The objective of this notice is to achieve reductions in releases of chlorine in wastewater effluents. Results indicate that 80% of the facilities met the risk management objective of the notice and releases of chlorine in wastewater effluents were effectively reduced by 85% using P2 techniques. The most popular P2 actions taken by the facilities involved process modifications which included the use of dechlorination and ultraviolet disinfection.

Pollution prevention planning notice requirements

In December 2004, Environment and Climate Change Canada published a P2 Planning Notice in the Canada Gazette. The persons subject to this notice are owners or operators of wastewater systems that in either 2004 or 2005 discharged, to surface waters, 5 000 cubic metres per day or more of effluent with a total residual chlorine concentration of greater than 0.02 mg/L. 85 wastewater systems in Canada met these criteria and were required to prepare and implement a P2 plan that takes into consideration reducing their total residual chlorine concentrations to 0.02mg/L or lower by December 15, 2009. Owners of wastewater systems (in other words, municipalities) were required to submit information to the federal Minister of Environment once their P2 plan was prepared and again once they had fully implemented the activities outlined in their P2 plan. These submissions are made available to the public and the information presented in this document is derived from these submissions.

Information reported for the notice

The Minister of Environment has received declaration of implementation submissions from 69 facilities that declared they have fully implemented their P2 plan, while an additional 2 facilities have been granted time extensions to implement their plans for which the deadlines have not yet passed. The remaining 14 facilities have not submitted their declarations of implementation.

Methods used to meet objectives of the notice

There are several alternative technologies available to disinfect treated wastewater effluents while effectively protecting the environment and human health. The P2 planning notice allows owners of wastewater systems some flexibility to choose the disinfection technology that best suits their facility in order to meet the risk management objective of the notice which is to reduce the concentration of total residual chlorine to 0.02 mg/L.

Overall achievement of the notice

To date, 80% of wastewater systems met the risk management objective of the notice; that is, they implemented P2 plans that considered actions to achieve and maintain a concentration of total residual chlorine that is less than or equal to 0.02 mg/L in the effluent released to surface water. Based on information reported in the declaration of implementation submissions, the concentration of total residual chlorine discharges have been reduced by 85% compared to the 95% anticipated reduction reported in the declaration of preparation submissions.

Chart 1 illustrates the reduction in the concentration of total residual chlorine discharged to surface water in the preparation year and results achieved in the implementation year for those who implemented their P2 Plans.

In some cases, facilities implemented P2 plans that exceeded the requirements of the notice. For example, 33% of systems that implemented their P2 plan reported a 100% reduction in total residual chlorine by upgrading their disinfection process to ultraviolet irradiation. Furthermore, in some cases, the scope of anticipated and completed actions in the P2 plans go beyond requirements to address “chlorine” and covered water/energy waste, and source control actions for other substances found to be toxic under CEPA 1999 such as mercury and nonylphenol and its ethoxylates.

Looking ahead: environment Canada’s proposed regulatory framework for wastewater

On July 18, 2012, the Government of Canada published the final Wastewater Systems Effluent Regulations in Canada Gazette, Part II. Establishing the regulations is the Government of Canada’s action to implement an agreement reached through the Canadian Council of Ministers of the Environment (CCME) in 2009. These regulations include the country’s first national standards for wastewater treatment. They propose clear standards for wastewater treatment and take a step towards managing overflows from combined sewers.

Background

Over the past century, the use of chlorine has become a common method used to disinfect wastewater effluents. Chlorine is a powerful disinfectant and is easy to use. In Canada, there are approximately 400 wastewater treatment systems that use chlorine and discharge wastewater effluents to surface waters such as rivers, streams, lakes, and oceans. Total discharges are estimated to be approximately 6 million cubic meters/day.

Following detailed scientific assessments, inorganic chloramines and chlorinated wastewater effluents were found to be toxic under CEPA 1999. These scientific assessments demonstrated that either substance may enter the environment in a quantity or concentration or under conditions that may have an immediate or long-term harmful effect on the environment or its biological diversity; or they may constitute a danger to the environment on which life depends.

P2 planning was selected to address inorganic chloramines and chlorinated wastewater effluents as it allows facilities to choose an alternative disinfection technology that best suits their needs in order to meet the risk management objective.