These wastewater are treated prior to their disposal, effectively reducing the amount of elements, sulfates and nitrates. In that scenario, valuable metals such as copper, nickel and cobalt are lost. But what about finding a way to both treat the wastewater and recover the valuable metals?
Based on that idea, two groups at LTU (Biochemical Process Engineering and Mineral Processing) combined their forces to develop a novel approach to treat mining wastewater that will enable the recovery of valuable metals in the form of metal sulfide nanoparticles. The team consists of Dr. Leonidas Matsakas, Dr. Yousef Ghorbani and Dr. Alok Patel. Recently they got granted a SEK 500 000 project by CAMM2 to work on their idea and investigate the potentials of biological systems to treat mining wastewater and convert the metal present there to metal sulfide nanoparticles.
Use of specific fungal cells or their enzyme extracts can react with the sulfate that is present in the mining wastewater, converting it to sulfide. In turn, sulfide reacts with different metals such as copper, nickel, silver, cobalt and lead and form the corresponding metal sulfides. These metal sulphide are usually insoluble and can be separated from the wastewater leading to their recovery. What is more important? That under specific conditions nanoparticles, nanodots or nanowires can be formed. Such products not only facilitate to recover the metals but also find high-end applications such as biomedical imaging, optoelectronics and semiconductors among others.
"If we manage to establishment such a process, we will not only offer a sustainable method for the treatment of mining wastewater but we will also recycle valuable metals that otherwise they would get wasted and most importantly generate materials that will offer additional revenue", says Leonidas Matsakas. In that way, we will convert a waste to a new resource.
"Given the significance and scale of acid mine drainage issue, which the UN has even labeled it the second biggest problem facing the world after global warming, it is important to explore the novel approaches in treatment, not only to neutralize the AMD, but also aim to turn it into a value", says Yousef Ghorbani.
The project Microbial Valorisation of acid mine drainage sludge (ValorAMD) is funded by the Center for Advanced Mining Technology and Metallurgy (CAMM2) at Luleå University of Technology as part of the High-risk projects annual call.