Proposed Changes to Trade Waste Acceptance Criteria (Nitrogen and Ammonia)
We’re improving the way we manage trade waste and are proposing some changes to the nitrogen-based trade waste parameters - Total Kjeldahl Nitrogen (TKN) and Ammonia.
The changes will simplify processes for our trade waste customers.
We’re seeking feedback from trade waste customers about the proposed changes, outlined below.
Why the changes?
Various upgrades at Melbourne Water’s Eastern and Western Treatment plants have reduced the risk that nitrogen compounds pose to the sewerage system. The proposed changes in acceptance criteria (limits) of both Total Kjeldahl Nitrogen and Ammonia will more accurately reflect the current risk they pose at the treatment plants.
How was the review done?
A metropolitan water industry working group (Yarra Valley Water, South East Water, Greater Western Water and Melbourne Water) assessed the current nitrogen limits (TKN and Ammonia) against the Eastern and Western Treatment plants’ risk tolerance to nitrogen loads.
The two limits were chosen to minimise costs for processing trade waste and to avoid incurring non-compliance charges and remediation requirements. The proposed increased limits will allow Melbourne Water’s Eastern and Western treatment plants to safely maintain their processes and Environment Protection Authority Victoria licence limits.
What are the proposed changes?
From section 2.3 (Nitrogen) of the Trade Waste Acceptance Criteria
|Current Acceptance Criteria||Proposed Acceptance Criteria|
The Occupier must not discharge trade waste with a concentration of Total Kjeldahl Nitrogen greater than 500 mg/litre.
|The Occupier must not discharge trade waste with a total mass load of Total Kjeldahl Nitrogen exceeding 788 kg/day (expressed as N) unless its concentration is no greater than 500 mg/L.|
The Occupier must not discharge trade waste with a concentration of Ammonia, plus ammoniacal ion (expressed as N) greater than:
i. 50 mg/litre, except as provided by this paragraph.
ii. 200 mg/litre, where -
(A) the trade waste discharge can only be received by Melbourne Water’s Western Treatment Plant
(B) a risk assessment has been conducted
(C) the occupier can comply with a restricted pH range of 6.0 to 8.0, and(D) the Occupier has demonstrated, that commonly available waste minimisation technology has been applied to the best extent possible.
The Occupier must not discharge trade waste with a concentration of ammonia, plus ammoniacal ion (expressed as N), greater than:
(i). 50 mg/L, or(ii). 200mg/L if the pH is within the restricted range 6.0 to 8.0
We’re proposing to have Ammonia limits consistent across both the Eastern and Western Treatment plant catchment areas and to align the Total Kjeldahl Nitrogen limit with the other chargeable parameters (Biochemical Oxygen Demand and Total Suspended Solids) using a combined load and concentration limit.
What are the benefits of these changes?
The benefits will include:
- Reducing the consequence of a trade waste customer breaching trade waste compliance and having to implement improvements and/or capital costs to meet the limit.
- Reduced administrative burden for metropolitan retail water companies, Melbourne Water and trade waste customers where non-compliance is identified and if the customer needs to apply for a Customer Specific Acceptance Criteria (CSAC).
- Elimination of the need to apply for a Customer Specific Acceptance Criteria (CSAC), avoid CSAC processing fees and the requirement to re-apply for a CSAC every three years.
- Easier to understand Total Kjeldahl Nitrogen and Ammonia limits for trade waste customers.
- Consistent and equitable limit requirements for trade waste customers across both the Eastern Treatment Plant and Western Treatment Plant catchment zones.
When will the changes take effect?
For these changes to take effect, the Essential Services Commission requires a customer impact assessment to be completed, based on customer consultation and feedback. All metropolitan water businesses are consulting with customers about the proposed changes and what they mean for them.
It is anticipated that the new Acceptance Criteria will be applicable by the end of 2022, subject to the Essential Service Commission’s approval.
Consultation with our customers is now closed.
Our online survey is now closed for comment. We’ve received positive feedback from our customers about the proposed changes. All customers advised us that they understood why the changes were being made and were supportive of them. Our customers will not be impacted by, and most will benefit from the changes.
We’ll now work with the other metropolitan water authorities to prepare a customer impact assessment. This will be based on all the feedback received from all metropolitan water authorities. Once we’ve completed this assessment, we’ll submit it to the Essential Services Commission in September for approval.