With rapid economic growth, aggravated environmental pollution has become a serious issue worldwide. Therefore, pollution control is imperative for sustainable development and is critical for ecosystem and human health. Excessive chemicals and energy have been used to control pollutants, which causes secondary pollution and side effects.

Biological processes are regarded as promising and sustainable. The bio-parts of pollutants are degraded through microbial activities, where complex organic matters are degraded and nutrients such as nitrogen and phosphorus are removed. Archaea and bacteria are important in such processes. For example, the denitrifying anaerobic methane oxidation (DAMO) process, through which methane is oxidized anaerobically, requires the involvement of archaea. Still, anaerobic ammonia-oxidizing (anammox) bacteria are responsible for nitrogen removal from both engineered and natural water systems. Biological processes are developing quickly with exciting breakthroughs in both theory improvement and technology innovation.

Aside from pollutant removal, biological processes are integrated with energy production and resource recovery. Archaea and bacteria play important roles in converting carbon, nitrogen, phosphorus and other pollutants into energy and valuable chemicals. However, issues behind process efficiency and stability remain unknown, such as microbiome dynamics, metabolic mechanisms, and identification of novel microorganisms. These investigations will optimize current biological processes and innovate emerging technologies.

This Special Issue aims to collate original research and review articles that focus on biological processes for pollution control. We invite submissions from global experts who are specialized in environmental biotechnology. We welcome original and high-quality research articles, short communications, as well as technical perspectives, mini-reviews, and full-length reviews.

Potential topics include but are not limited to the following:

• Emerging biotechnologies for wastewater treatment
• Environmental microbiology for industrial wastewater treatment
• Molecular methods for studying microbial ecology
• Bioreactors for resource recovery
• Identity, physiology, ecology and population dynamics of ammonia-oxidizing archaea in wastewater treatment
• Relationships between ammonia-oxidizing archaea and bacteria and their abundance and distribution in wastewater treatment
• Characteristics, activity and diversity of archaea in denitrifying anaerobic methane oxidation
• Nitrogen removal performance and mechanism through synergy between archaea and bacteria in denitrifying anaerobic methane oxidation
• Simultaneous pollutant removal and methane production in anaerobic digestion
• Competition between methane-producing archaea and sulfate-reducing bacteria in anaerobic digestion