Textile mills that use wet processing: final summary report

Textile mill effluents (TMEs) are wastewater discharges from textile mills produced during wet processes such as scouring, neutralizing, desizing, mercerizing, carbonizing, fulling, bleaching, dyeing and printing. They are complex mixtures of chemicals, whose composition varies over time and from one mill to another. Untreated TMEs may include high concentrations of nonylphenol and its ethoxylates (NP-NPEs), suspended solids, metals, and other organic substances. Untreated TMEs can also exhibit extreme pH variations and elevated temperatures.

Assessments of NP-NPEs and TMEs found that they were entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity. As a result, in 2002, NP-NPEs and TMEs were added to the List of Toxic Substances in Schedule 1 of the Canadian Environmental Protection Act, 1999 (CEPA 1999).

Prior to the publication of the notice requiring the preparation and implementation of pollution prevention (P2) plans in respect of effluents from textile mills that use wet processing (TMEs) and NP-NPEs, NP-NPEs constituted a major class of surfactants used in the textile wet processing industry. It was estimated that the textile sector was responsible for 18% of the NP-NPEs released annually in Canada.

Pollution prevention planning

In 2002, Environment and Climate Change Canada published a risk management strategy in respect of effluents from textile mills that use wet processing (TMEs) and NP-NPEs Under CEPA 1999. The strategy, which was revised in 2005, outlines the risk management objectives as well as the recommended risk management instrument, which was P2 planning.

P2 planning notices are instruments that require specified persons, including companies, to prepare and implement P2 plans. P2 encourages pollution reduction at the source rather than treatment and is defined as “the use of processes, practices, materials, products, substances or energy that avoid or minimize the creation of pollutants and waste, and reduce the overall risk to the environment or human health” (CEPA 1999).

P2 planning notice requirements

Environment and Climate Change Canada published the notice in the Canada Gazette on December 4, 2004. Persons subject to the notice included all wet processing textile mills that discharged their effluents to a municipal wastewater treatment system and had a daily effluent flow greater than 30 m³/day, based on average annual discharge, at least 1 year between 1999 and 2003.  Affected persons were required to prepare and implement a P2 plan that took into consideration the following 2 objectives:

• reducing, by 2009, the annual use of NP-NPEs by at least 97%, relative to the annual use for the base year (1998 for most mills)
• reducing the toxicity of TMEs to a level equivalent to or greater than 13% IC₅₀ (50% inhibiting concentration) by 2009

Subject mills

Over 60 mills submitted declarations that plans were prepared and being implemented, identifying themselves to be subject to the notice. The majority of these mills were located in Quebec (59%) and Ontario (38%). The remainder were located in Nova Scotia (3%). As of December 2011, 21 of these mills have closed or ceased wet processing activities.

A mill may perform 1 or several types of wet processing activities. The percentage of mills performing each wet processing activity, according to their declarations of implementation, can be seen in Figure 1 below.

Figure 1: textile mill wet processing activities

Results achieved

The NP-NPE reduction target of 97% has been surpassed; NP-NPE use was reduced by 99.99% from the base year (1998 for most mills) to the implementation year (2009 for most mills). The amount of NP-NPEs used declined from 207 069 kg in the base year to 20.2 kg in the implementation year, as can be seen in Figure 2 below.

Figure 2: quantities of NP-NPEs used by textile mills

Mills were required to reduce their toxicity (TME) to a level equivalent to or greater than an IC₅₀ of 13%. A minimum of 4 toxicity tests were to be performed throughout the year in order to determine if this objective was met. However, where mills performed less than 4 toxicity tests, they were considered by Environment and Climate Change Canada to have met the objective if all toxicity results were equal to or above 13%. This assumption introduces some uncertainty to the results. Where mills took more than 4 toxicity tests, those that passed at least 4 tests were considered to have met the objective. The 4 mills that did not provide any toxicity test results are now closed.

According to Environment and Climate Change Canada’s analysis of active mills, the majority (61%) were considered to have met the objective and a further 31% demonstrated that they passed some, but not all, of their toxicity tests. Therefore, 92% of active mills were considered to have met or partially met the requirements. Eight percent of mills did not pass any of their toxicity tests. However, overall TME toxicity levels have improved since the notice was published.

Conclusion

The notice has largely been successful. The risk management objective for NP-NPEs was surpassed and although the risk management objective for TMEs was not fully achieved, it was met or partially met by 92% of mills.

NP-NPEs will continue to be monitored in wastewater treatment plant effluents to determine if further risk management of other sources is warranted.

NP-NPEs are not solely responsible for TME toxicity, as can be seen from the results achieved. Other substances contribute to TME toxicity including: phosphates, dyes and solvents. Currently, many substances that are used by textile manufacturers are being assessed under the chemicals management plan (CMP). If it is determined that any of these substances are considered harmful to human health or the environment, risk management actions can be taken to contribute to further reducing TME toxicity. Additionally, the Wastewater Systems Effluent Regulations established under the Fisheries Act include mandatory minimum effluent quality standards that can be achieved through secondary wastewater treatment. It is anticipated that these regulations will have a further effect on reducing the impact of TMEs on the environment.

Sources

• Risk management strategy in respect of effluents from textile mills that use wet processing (TMEs) and nonylphenol (NP) and its ethoxylates (NPEs) under CEPA 1999