The definition and impacts of trade waste

Trade waste is the term used for all liquid waste generated in industrial or commercial premises and discharged to the sewer. This includes contaminated groundwater, contaminated surface water and water used for business activities such as cooling towers, kitchens, industrial processes or cleaning plant.

Trade waste does not include sewage or domestic waste water produced by humans or from residential premises.

Depending on the jurisdiction, trade waste can also be referred to as liquid waste, industrial waste, industrial wastewater or trade wastewater.

The impact of trade waste discharges

Trade waste can contain contaminants such as fats, oils and grease (FOG), chemicals, heavy metals, nitrogen and phosphorus, suspended and dissolved solids and biological oxygen demand (BOD). If not managed properly, these contaminants can damage the sewer network, the biotreatment process and the environment, as well as harm the health and safety of those who work at sewage treatment plants and the general public.

For this reason, authorities and water utilities throughout Australia enforce controls on the concentration of contaminants in trade waste discharged to the sewer. These controls are specified in water utilities’ trade waste management procedures and trade waste agreements or consents.

Removing contaminants before discharge trade waste

Some premises are required to pre-treat wastewater to minimise trade waste contaminants being discharged. A variety of wastewater pre-treatment facilities are commonly used onsite, such as:

• Silt traps, screens or strainers (to remove suspended solid waste)
• Oil-water separation systems (to remove oil and water-immiscible organics)
• Grease traps or arrestors (to remove grease from kitchens or food-processing)
• Triple interceptors (to remove suspended solid waste and water-immiscible organics)

Protecting the sewer system with a trade waste agreement

If a business discharges trade waste to the sewerage system from an industrial, commercial, laboratory, commercial kitchen or trade process, then it needs to get approval from its local water utility. This approval is called a trade waste agreement or trade waste consent and may also be referred to as a trade waste permit or trade waste authorisation in other jurisdictions. A list of some of these businesses, also known as trade waste customers, can be found at the end of this post.

A trade waste agreement or consent outlines conditions for discharging trade waste to the sewer. These will usually include, but not limited to:

• daily discharge limits for one or more substances
• how the business will be charged for trade waste discharges
• acceptance criteria for trade waste discharges including contaminant thresholds for particular metal ions, organics and other waste characterisitics.

Depending on the type of business and trade waste produced, there also may be a requirement to regularly sample and analyse the trade waste discharge, and the agreement or consent will specify what testing or analysis is required, and how often sampling is required.

Failure to apply for a trade waste agreement or consent may incur a fine or other legal action.

The cost of trade waste disposal

Water utilities charge businesses to dispose their trade waste, and these charges can usually be found on the water bill. The cost of trade waste disposal is often dependent on the concentration of certain contaminants such as nitrogen, suspended and dissolved solids and BOD.

Charges will generally be higher if the site has previously been found to be non-compliant with any of the approved acceptance criteria specified in the trade waste agreement or consent.

Trade waste volumes may be metered but they are usually estimated as a percentage of the incoming water. If your charges are estimated from your water meter readings, and your site “consumes” a significant proportion of the incoming water (eg. in products, as irrigation or through evaporation from cooling towers – essentially incoming water that is not subsequently discharged to the sewer), you may be able to apply for a reduction – we have achieved this for a number of our clients.

We also recommend that you establish how your trade waste volume is actually calculated.  For example, it may be calculated as a percentage of an agreed water usage quantity, based on previous years water usage.  If this is so, and your water usage has been reduced due to water-saving initiatives, then you may be paying more than you should.  Again, we can help with this.

Manage trade waste contamination with cleaner production

If contaminants in your trade waste (e.g. organics causing high BOD) are adding significantly to your trade waste charges, there may be opportunities to reduce these charges by reducing contamination levels.

Cleaner production actions, such as reducing the amount of liquid waste generated, recycling or repurposing liquid waste or working with less toxic substances, can help reduce wastage of raw materials that contribute to contaminants. This not only reduces trade waste charges it also promotes more environmentally sustainable practices.

Waste management hierarchy

Another way to reduce trade waste contamination is by implementing the waste management hierarchy. This is the hierarchy published by EPA Victoria:

1. Avoidance
2. Reuse
3. Recycling
4. Recovery of energy
5. Containment
6. Disposal

Like all forms of waste, the ideal option for trade waste or wastewater is to not generate so much of it in the first place. Repurposing the trade waste or wastewater is the next preferred option, with the least effective option being to dispose the waste to the sewer.

Inorganic contaminants

Most of the inorganic contaminants in trade waste are not extracted at the sewage treatment plants and end up in the natural water or land environment. If possible, such inorganic contaminants should be prevented from entering the sewerage system and disposed of as hazardous waste, where it will be taken to commercial waste treatment plants and the harmful contaminants removed from the wastewater.

Who are trade waste customers?

Businesses discharging trade waste are trade waste customers. Trade waste customers are generally categorised as commercial customers or industrial customers depending on the type of business, industry, activity or trade waste discharged.

Commercial customers

Commercial customers generally discharge liquid waste deemed low risk like oils, food scraps and cleaning chemicals. Some of these customers include:

• retail food – Restaurants, cafes, takeaway/fast food establishments, hospital and nursing home kitchens, bakeries and butchers
• automotive – Mechanics, car wash, panel beaters, service stations
• commercial laundries – laundromats, dry cleaners, hospital and nursing home laundries
• shopping centres
• swimming pools and aquatic centres
• commercial businesses with cooling towers

Industrial customers

Industrial customers may discharge high risk liquid waste. Some of these customers include:

• food and beverage processing and manufacture
• paper and cardboard manufacture
• chemicals and other manufacturers
• businesses undertaking pharmaceutical and cosmetic activities
• businesses working with cement, stone and abrasives