Biological filtration for wastewater treatment in the 21st century: A data-driven analysis of hotspots, challenges and prospects

Biological filtration has been widely used in wastewater treatment around the world, yet achieving satisfactory removal of pollutants remains a challenge due to the complexity of water pollution. In order to reveal the hotspots and trends of biological filtration from the perspective of research innovation, 5454 SCI papers and 14,287 patents collected from the Web of Science Core Collection and Derwent Innovation Index database were analyzed by visualization techniques. The results showed that China ranked first in the number of both papers and patents, while the USA and Japan contributed significantly in papers and patents, respectively. Co-occurrence analysis obtained the mapping knowledge domains and demonstrated distinct associations between contaminants (“nitrogen”, “pharmaceuticals”, “personal care products”), chemicals (“carbon”, “activated carbon”, “media”), process (“biodegradation”, “adsorption” or “ozonation”) and characteristics (“kinetics”, “performance”, “diversity”). Moreover, this review summarized the recent advances of biological filtration media, microorganism and combined process being applied. It was concluded that environmentally friendly biological filtration (“phytoremedi”, “microalga”, “recirculating aquaculture system”), bio-enhanced biological filtration (“bioaugment”, “fungi”, “low augment”) and emerging pollutants (“emerging contamin”, “antibiotic resistance gen”, “organic micropollut”, “trace organic chem”) were the hotspots through data-driven analyses. Technology evolution path of biological filtration generally indicated the transition from conventional biological filtration for nitrogen and phosphorus removal to Fenton-biofiltration combined technology and finally to ozone-biological filtration. Furthermore, the technical innovation direction of the collaborative control of multi-media pollution, the low-carbon biological filtration and short-process technology was prospected. This work can serve as a quick reference for early-career researchers and industries working in the area of biological filtration.