Increasing pressure from the economy, the general public and the law, demand for the adoption of sustainable and environmentally friendly environmental processes has been rising quickly in recent years. When it comes to the monitoring, evaluation, modelling and treatment of contaminated water, air and solid waste streams, biotechnology provides a diverse range of opportunities. Because of their accuracy and consistency, biologically based methods for process modelling and source tracking of environmental pollutants are becoming more and more significant in this context. The various biotechniques that are currently available thus represent both established and emerging biotechnologies, while several elements of their effectiveness still need to be examined. For instance, the application of innovative biocatalysts and reactor designs, the comprehension of the dynamics and mechanisms governing the microbial population within a bioreactor and the evaluation and modelling of the performance of bioreactors during long - term operation. Novel biotechniques may transform how users rebuild technology for the sustainable use of various biological processes for the treatment of wastewater, air and solid waste if these mechanisms are recognized and the obstacles are removed. Over the course of six months, this special issue received 34 research/review submissions, of which 21 excellent papers (or 62%) were chosen for publication after undergoing a double-blind peer review. These papers, which have been approved, focused on the numerous fundamental and applied engineering aspects of various methods and procedures that may have real-world applications in the developing domains of environmental biotechnology. This special issue spotlights some difficult problems with environmental monitoring and pollution reduction that fall into five categories of subject research.