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Real-time Identification of Prohibited Organic Compounds in Sewers

Challenge Statement

How might we identify and quantify the presence of specific prohibited organic compounds in wastewater for timely intervention? 

Challenge Owners

Water Reclamation (Network) Department, Discharge Quality Branch

Background & Current Practice

The presence of prohibited organic compounds in wastewater may affect health and safety of workers maintaining our public sewerage system as well as the treatment processes of downstream used water treatment plants.

These compounds are prohibited under the First Schedule of the Sewerage and Drainage (Trade Effluent) Regulation [SD(TE)R]​ and are already being monitored routinely by PUB. However, many prohibited organic compounds cannot be rapidly detected, identified and quantified using existing available detection systems like the Photoionisation Detectors (PID) currently in use.

Areas of Opportunity

PUB is interested in acquiring systems and/or sensors that can identify prohibited organic compounds individually or as groups (e.g. functional groups). Such sensors and measuring devices would be deployed at the sewers and potentially even at industrial premises to closely and efficiently monitor, identify and facilitate source tracing of an illegal discharge. 

The solution would ideally be able to detect, identify and quantify, through direct measurement or through indirect methods, the entire range of 30 prohibited organic compounds stipulated in the First Schedule of the Sewerage and Drainage (Trade Effluent) Regulation [SD(TE)R]. We wish to understand from innovators the detection effectiveness and cost implications of such a solution to consider practical adjustments to its specifications. 

To supplement the above, PUB is also interested to detect the following compounds:
●  Acetone
●  N-cyclohexyl-pyrrolidone
●  N,N-Dimethylacetamide (DMAc)
●  Cyclopentanone
●  Dibutyl Phthalate, and
●  Octadencenamide / Oleamide

Key Considerations & Challenges

●  The proposed solution must be able to differentiate and identify individual or groups of compounds within the list of prohibited organic compounds 
●  The following is the sewerage condition that the solution must be able to cater for:
​​​     ○  Mixture of compounds present, either as liquid or gaseous state
     ○  High levels of total suspended solids
     ○  Presence of Hydrogen Sulfide (H2S)
     ○  Poor sanitation issues, e.g. smell​
​●  Th​​​e solution would ideally be able to detect prohibited organic compounds at concentrations of 1ppm or lower, depending on the location they are installed.
●  If the detection cannot be done continuously, the solution should carry out detection or sampling at intervals of not more than 5 minutes.
●  The solution would ideally be able to detect the compounds when present in the wastewater (i.e. in liquid state) rather than detecting the compounds from the air space above the wastewater. If pre-treatment is required for the solution, it should be included as part of the provided system, with details indicated in the proposal.
●  The operation of the solution should be automated and unmanned with low maintenance
●  The maintenance frequency of the solution would ideally be once every quarterly or less.
●  The solution would ideally have low power requirements, but power sources of up to 500W could be made available if needed.
●  The solution would ideally have a footprint of less than 1m2.
●  The solution would be deployed at sewers, at a depth of up to 15m. The solution would monitor mixed trade effluent from a cluster of 15 to 50 industrial premises, or the effluent directly from an industrial premise.
●  PUB is open to solutions that analyse the extracted samples outside the sewer. For such a set-up, your proposal should include details of the sample extraction process.
●  Cost is a consideration, as low-cost sensors would allow PUB to deploy them more widely.
●  Solutions that do not rely on a direct method of detecting prohibited organic compounds but instead achieves the same level of sensitivity, specificity and accuracy of a sensor may be considered if the solution can demonstrate an equivalent level of performance.
 ●  A proposal for system integration is not necessary at the current stage, but PUB is interested to understand what you have considered.

Current Technology Status

Existing Photoionisation Detectors (PID)
●  Can only measure the total VOC in its gaseous state. Semi-volatile organic compounds (SVOCs) are not detectable.
●  Unable to identify any of the 30 prohibited organic compounds individually.

Expected Timeline

Total project period: less than 18 months
Solution development and deployment: up to 9 months
Solution testing and data analysis: up to 6 months

Expected Outcomes

A prototype sensor or equivalent system, validated in simulated environments, is demonstrated to be effective for detection and quantification of some or all of the prohibited organic compounds. If proven to be effective, the prototype system will be further validated in test sewer sites to determine the detection effectiveness under real operating conditions. If the pilot is successful, the solution would be provided to PUB through a leasing model. ​