Among the diverse biological wastewater treatment methods,
aerobic processes, especially activated sludge, dominates. Thus,
most of the new toxicity assays that have been developed focus
on their application to activated sludge. Recent advances in membrane
technology have made anaerobic wastewater treatment a
very attractive process [5]. However, anaerobic processes, especially
their methanogenic components, are very sensitive to toxic
compounds [6]. Well-known toxic compounds including ammonia,
sulfide, volatile fatty acids, metal ions and organics, can disrupt
the anaerobic digestion processes to varying degrees. Despite the
general recognition that prompt detection of toxic compounds is
vital to the smooth operation of anaerobic processes, there has
been little advance in measuring toxicity to anaerobic process in
the past three decades. Meanwhile, research and development
within the domain of biosensors has bloomed [7–10], and some
of these biosensors clearly have the potential to be used in the
context of biological WWTPs. This review will cover toxicity measurement
methods for both aerobic and anaerobic processes, and
present a range of promising biosensors that may be adopted for
use in WWTPs. Although ecotoxicological assays – such as those
based on the growth inhibition of algae or plants, the mortality of