Innovative engineer uses bacteria to remove nitrogen from wastewater

Posted 14 August 2017

Dr Raj KurupNitrogen removal is set to become quicker and cheaper for Australian utilities as a result of a new process developed by Western Australian engineer Dr Raj Kurup. 

Environmental Engineers International CEO Dr Raj Kurup independently developed the EEI anammox process, an approach to removing nitrogen from wastewater that utilises bacteria present in activated sludge without the need to add pure anammox bacteria. The achievement led to Kurup becoming one of a number of water specialists being named as Engineers Australia’s Most Innovative Engineers of 2017.

Kurup’s variation on conventional processes is based on anaerobic ammonium oxidation and was developed through his work with a client aimed at treating abattoir wastewater.

“After running an abattoir effluent treatment system for 50 years, we upgraded the treatment plant to a conventional biological nitrification-denitrification system,” Kurup said.

“But it became highly impractical to use the conventional system, because of the high level of ammonia associated with the influent BOD [biochemical oxygen demand]. There was a high nitrogen to BOD ratio.”

The plant was adding methanol to treat the nitrate levels, but the costs were escalating and Kurup was asked to find a better solution to the problem.

“To our understanding, there are no working wastewater treatment plants that employ the anammox process for nitrogen removal,” Kurup said. 

“The international firms that are currently trialling and promoting anammox technology state that in order to implement the anammox process, they have to import the pure bacteria from overseas. It then takes about two years for the bacteria to reach a steady state condition for substantial nitrogen removal; it’s a very slow growing bacteria.  

“The conventional belief is that you need to have an isolated batch of anammox bacteria to inject into the treatment plant. But our hypothesis was that the anammox bacteria should be inherent in any conventional wastewater treatment system, such as an activated sludge plant”. 

Rather than import the pure bacteria from overseas, which is expensive and time consuming, Kurup tested for inherent anammox bacteria in his client’s effluent system. 

“We did some laboratory tests and found that anammox bacterial biomass was available within the existing system. We then had the confidence to achieve the anammox process without any importing from overseas,” Kurup said.

“We introduced the anammox process and found that our anammox bacteria was working. Within a few months’ time we completely stopped the addition of methanol, making the process completely anammox.

“We’re still meeting the regulatory requirements, much below in fact; the target is 45mg/L of nitrogen, but we get a flow of 15mg/L for nitrogen in the treated effluent.”

Developing the new process did not come without challenges. Kurup said the sensors needed to track the process were initially unavailable, making it difficult to analyse results. 

“It took about a year to get all the sensors we wanted. We worked with the available sensors we had and used some surrogate measures to understand the impact of the ones we did not have. In a way, our testing was partially blind,” Kurup said.

“We worked with the available facilities we had. But we actually achieved the results before we got all the sensors and they then validated our findings.”

This process has been proven to save power costs by up to 55%, as well as saving time and money from importation. 

“The system is much more robust [than those being used overseas]. In Chinese and European examples, they claim that they have to use a pure bacteria, whereas we didn't see that as necessary. That saves millions of dollars for a larger system,” Kurup said. 

“Furthermore, the delay through customs in getting the bacteria from an overseas country takes a lot more time than implementing bacteria from your own system.”

Kurup also pointed out that the anammox technology being used overseas is difficult to operate in during winter. 

“Our process has been operating without any difficulty in temperatures lower than 10oC. This eliminates the requirements of heating the treatment plants or shifting to the conventional nitrification-denitrification system in winter months.

“We think that wastewater industry in Australia can definitely benefit from implementing this technology.”

Kurup was far from the only engineer recognised for his or her work in the water sector. UNSW Pro Vice-Chancellor Professor Ana Deletic was recognised for her work in developing Green-Blue Walls, a low-energy, low-cost vegetated water filter aimed at reducing phosphorus concentrations in light greywater and urban stormwater.

Meanwhile, Logan City Council Maintenance Engineer Gregory Kelly made the list thanks to his Flooded Roads Smart Warning System, an autonomous system capable of not only warning local drivers of impassable roads but also updates emergency services and local authorities.

BMT WBM Senior Flood Engineer Carrie Dearnley also earned a spot on the list by addressing the communication gaps between the agencies involved in flood planning and those in charge of emergency responses. Her Flood Decision Support System is an intuitive system aimed at allowing emergency responders access to information on things such as flood levels on evacuation routes.