Recycled water specification
The recycled water quality specified for the Rosehill Recycled Water Scheme is summarised in the following tables.
The recycled water will meet the quality limits detailed in Table 1.1.
Additional recycled water quality parameters are detailed in Table 1.2.
Table 1.1 specifies the target and maximum levels for the recycled water quality that will be monitored continuously by AquaNet. If, at any time, one of the maximum limits is exceeded the recycled water will be considered to be “out of specification”. AquaNet will immediately stop all recycled water supply and provide advice according to the Operating Protocols. The supply of recycled water will not recommence until the recycled water plant has achieved a minimum of 30 minutes of production within the specified limits.
Table 1.1 – Recycled Water Quality – Continuously Monitored
| Parameter | Units | Target | Limit to Trigger Product Failure |
|---|---|---|---|
| Total Dissolved Solids | mg/L | < 50 | ≥ 60 |
| pH | pH units | 6.5 to 8.5 | < 6.0, > 9.0 |
| Chlorine Residual 1 | mg/L | 1 | < 0.7, > 5.0 |
| Turbidity | NTU | < 0.5 | ≥ 2 |
Notes:
1 The chlorine dosing equipment will be capable of dosing up to 5 mg/L. The chlorine residual may be provided by the presence of chloramines as opposed to “free chlorine” provided the bacteriological and virus limits detailed in Table 1.2 are met at all times.
1 Chlorine levels will be monitored at the Recycled Water Treatment Plant, at the reservoirs and the extremities of the distribution network.
Table 1.2 specifies the 95%ile levels on a 12 month rolling average of other parameters in the recycled water that cannot be reliably measured continuously (on-line). The table includes the frequency that each of these parameters will be analysed by AquaNet. Additional analysis will be undertaken by an independent third party NATA accredited laboratory to verify the AquaNet test results.
If, at any time, AquaNet becomes aware of an exceedance in any of these parameters AquaNet will initiate actions to return the parameter to below the 95%ile level. Additional sampling will be undertaken by AquaNet until the parameter returns to normal levels.
Table 1.2 – Recycled Water Quality – Additional Monitoring
| Parameter | Units | Monitoring Frequency (one 24 hr composite sample) | Recycled Industrial Water Quality (95%ile) (95%ile is calculated on 52 week rolling average) |
|---|---|---|---|
| Alkalinity 2 | mg/L (as CaCO3) | Weekly | <20 |
| Aluminium | mg/L | Weekly | <0.1 |
| Ammonia | mg/L | Weekly | <1 |
| Iron (soluble) | mg/L | Weekly | <0.05 |
| Manganese | mg/L | Weekly | <0.05 |
| Zinc | mg/L | Weekly | <0.1 |
| Biochemical Oxygen Demand | mg/L | Weekly | <2 |
| TDS | mg/L | On-line | <55 |
| pH | pH units | On-line | 6.5 to 8.5 |
| Chlorine residual 3 | mg/L | On-line | 1 to 3 |
| Turbidity | NTU | On-line | < 1 |
| Total Nitrogen | mg/L | Weekly | <10 |
| Total Phosphorous | mg/L | Weekly | <2 |
| E.coli Coliforms | CFU per 100mL | Weekly | <1 in 100ml |
| Total Coliforms | CFU per 100mL | Weekly | <10 in 100ml |
| Virus | Organisms per 50L | Monthly | <1 in 50L |
| Parasites | Organisms per 50L | Monthly | <1 in 50L |
| TOC | Ppm | On-line | < 5 |
| Silica | mg/L | Weekly | <2 |
| Total Iron | mg/L | Weekly | <0.5 |
Notes:
2 Alkalinity levels of less than 20mg/L will be aggressive to certain types of materials and some metals and can result in accelerated corrosion on cast iron, copper and concrete pipes and fittings.
3 Chlorine residual of greater than 1mg/L can result in copper corrosion, this is similar to the situation with Potable Water.
An independent assessment of recycled water quality and use in industrial applications is provided by Dr Nicholas Milne, Institute for Sustainability and Innovation, Victoria University and is available below.
A more detailed report titled Guidance For the Use of Recycled Water by Industry is also available.