Sustainability Matters has partnered with Aquacell to promote onsite water reuse. Please visit the November Newsletter, Risk Management 101.
What’s the most important question we can ask ourselves when designing an onsite wastewater recycling scheme?
How can we be sure every ounce of treated water is safe for reuse?
Nothing is more important than public safety. I think we can all agree on that. If we’re going to fully engage decentralized wastewater reuse as a water conservation strategy in the decades to come, we need to approach implementation with public health at front of mind. This all begins with risk management – putting in place the proper mechanisms to minimize or eliminate the risk of contaminated water entering the supply.
Onsite Water Reuse Risk Management 101
Validation (Can it Work?) is a desktop exercise where you prove with science the scheme will achieve the specified water quality. This takes place prior to installation.
Verification (Is it Working Now?) is a means to determine in real-time if the system is functioning according to water quality objectives.
Ongoing Sampling (Did it Work?) is ‘end of pipe’ sampling and water quality testing to ensure the system is working as prescribed.
You’ll notice the title of this segment is ‘Risk Management: Reactionary or Preventative?’ Seems like a pretty obvious answer you may say. Who wouldn’t choose preventative measures over reactionary measures? Sure doctor, I’ll be looking forward to that bypass surgery as opposed to preventative medication now. Silly right? Well unfortunately, the answer hasn’t been so obvious for regulators who oversee wastewater reuse. Sadly, most US states (if not all) still take a reactionary approach to risk management when it comes to treated water quality. Consequentially, the majority of existing onsite reuse schemes cannot promise every ounce of treated water is safe. Current regulations for onsite reuse schemes call for ongoing monitoring or ‘end of pipe’ sampling as the principle risk management element. End of pipe sampling means someone goes to site and takes frequent water quality samples to make sure the treated water quality is safe. The sample is then taken to a lab and water quality results will be conveyed to the system operator days, sometimes weeks later. So what if the sample comes back and the water quality was not safe for reuse? Whoops… too late! You can see how this approach is reactionary. And considering the technology we now have at our disposal, I would argue it’s antiquated as well.
The ‘Verification’ step is the necessary element for preventative risk management. Not to undermine the two other elements – as these are extremely important for successful risk management – however, they do not encompass the ability to ensure every ounce of water is safe for reuse. The verification measure does just that by continuously monitoring a number of different water quality indicators within the treatment process in real-time. These ‘Critical Control Points’ or ‘CCP’s’ within the treatment process will then trigger corrective action automatically (again, in real-time) if monitoring reveals the water quality is outside parameters set by system operators. Thus, you’ve eliminated the risk of sending contaminated water back into the supply – fully protecting public health. This risk management methodology is called HACCP (Hazard Analysis and Critical Control Points) and is borrowed from the food and beverage industry. Learn more about HACCP here.
More Safe, Less Cost
Current US policy for onsite water reuse is silent on the issue of preventative risk management. The real issue with current policy is that we’re relying on end of pipe sampling to protect public health. To compound the safety implications, it should also be noted that the excessive amount of end of pipe sampling required often derails decentralized projects due to lab expenses – and the implication on operational costs. It’s important to understand that not only does the preventative approach make onsite reuse schemes more safe and reliable; it also makes them more economically viable. Because you have the real-time monitoring and verification element in place, your scheme requires less end of pipe sampling. Instead of relying on the end of pipe sampling as your only water quality indicator, it simply serves as confirmation that the scheme ‘did work.’
In a nutshell: Real-time verification = Less end of pipe sampling = Less operational cost = More safe, Less cost. Now that’s innovation. And that’s what America is all about – we like cheaper but better, don’t we?
Sustainability Matters welcomes your comments and questions as your informational resource for Aquacell Water Recycling Solutions.