A pilot-scale partial nitritation-anammox process for treatment of anaerobic sludge digester effluent

In most of the wastewater treatment operational practices with anaerobic sludge digestion, the ammonia rich centrate (>100mg/L) is recycled back to the main treatment line which increases the NH₄⁺-N loading to the treatment by as much as 10–30% (Fan 2020). The partial nitritation-anammox (PN/A) process is a biological process that provides an environmentally, economically, and technically sound solution to treat anaerobic sludge digester effluent. The application of the anammox process in the wastewater system could result in higher nitrogen removal in the digester effluent as there have been related research conducted at lab-scale using synthetic wastewater (Awolusi et al., 2020). However, due to the process sensitivity to operating conditions, there is a need to optimize at pilot scale to emerge as an efficient process, especially in the South African environment as this technology has a possibility to be promoted as an alternative and/or additional bioprocess to be applied in full scale throughout the country.