From wastewater to renewable resource

As the population continues to increase, so does its environmental footprint. The potential for negative impacts from poorly managed public systems is a significant risk – particularly when it comes to wastewater.

Managing wastewater streams is a significant environmental problem and an important issue globally. Wastewater treatment has become more complex as denser populations generate increasingly more pollution and waste.

By-products of wastewater treatment – often referred to as “sludge” – are among the most pressing concerns. Managing solid residual waste has presented a particular challenge. The only way to continually safeguard public and ecological health is through the development and evolution of technology to handle these increased pressures.

Instead of amassing ever more sludge and solid residuals, the global trend has moved in the direction of viewing wastewater as a resource. What if we could develop innovative technology to minimize sludge, recover nutrients and reuse wastewater more effectively?

Wastewater experts are working to do just that. A leading-edge, cost-effective integrated system has been developed and patented at the University of British Columbia, Canada (UBC). The system, known as the Microwave Enhanced Advanced Oxidation Process (MW-AOP), applies microwave heat and oxidants (hydrogen peroxide) to break up wastewater sludge and improve and shorten the overall wastewater treatment cycle. This integrated system involves three components: the MW-AOP technology; a struvite crystallizer; and two-phase advanced anaerobic digestion.

WSP subsequently completed a feasibility study of the integrated sludge treatment/resource recovery system for treating dairy manure that included concept design and costing, as well as assessing the economics of the process.

Currently, WSP is collaborating with the UBC research team on pilot projects at two municipal wastewater treatment facilities in the Lower Mainland area of British Columbia. The pilot projects are designed to demonstrate the effectiveness of the integrated system in enhancing treatment of sludge generated at municipal wastewater treatment facilities. WSP was also on the project team for a recent pilot project using the integrated system for treating dairy manure at the UBC Research farm.

In the integrated system, the microwave process (MW-AOP) pre-treats the sludge ahead of anaerobic digestion, liquefying the solids and allowing increased biogas production, higher organic loading to the digester, and smaller digestion reactors with shorter retention times.

Essentially, that means lower operating costs for treating and handling solid residual waste. Solid waste could be reduced by up to 80 percent, based on the most recent test results. 80 percent less solid waste means 80 percent less need to transport and dispose of that waste.

However, the integrated system doesn’t stop at merely reducing solid waste. It also allows for the extraction of byproducts like nitrogen and phosphorus, resulting in the mineral struvite. Struvite is a sustainable slow-release fertilizer that can be used as a replacement for chemical fertilizers. This can generate greenhouse gas credits during production and revenue through the sale of the product.

As new regulations and policies are put in place to manage wastewater and keep our water sources clean, there are opportunities for agencies to develop new business models, work in partnership with others and harness new technologies to meet these emerging challenges.

Making use of innovations like the integrated MW-AOP system is a critical step for governments to meet increasing expectations for environmental protection and integrated management of wastewater.