Sewage Treatment with Anammox

TLDR

Sewage treatment must remove organic matter and nitrogen to protect water bodies, but conventional processes are energy‑inefficient and rely on aerobic conditions; anammox bacteria offer a lower‑energy alternative that can also potentially recover energy from organic matter. The study investigates process innovations to accelerate anammox and maximize energy recovery from organic matter. The authors examine how to speed up the anammox process and utilize all organic matter for energy generation.

Abstract

Organic matter must be removed from sewage to protect the quality of the water bodies that it is discharged to. Most current sewage treatment plants are aimed at removing organic matter only. They are energy-inefficient, whereas potentially the organic matter could be regarded as a source of energy. However, organic carbon is not the only pollutant in sewage: Fixed nitrogen such as ammonium (NH4+) and nitrate (NO3−) must be removed to avoid toxic algal blooms in the environment. Conventional wastewater treatment systems for nitrogen removal require a lot of energy to create aerobic conditions for bacterial nitrification, and also use organic carbon to help remove nitrate by bacterial denitrification (see the figure). An alternative approach is the use of anoxic ammonium-oxidizing (anammox) bacteria, which require less energy ( 1 ) but grow relatively slowly. We explore process innovations that can speed up the anammox process and use all organic matter as much as possible for energy generation.