  Microbially-Induced Carbonate Precipitation (MICP) involves a series of
bio-geochemical reactions whereby microbes alter the surrounding aqueous
environment and induce calcium carbonate precipitation. MICP has a broad range
of applications, including in-situ soil stabilization. However, the reliability
of this process is dependent on a number of environmental conditions. In
particular, bacterial growth, bacterial activity, and precipitation kinetics
all depend on temperature. Batch test and microfluidic chip experiments were
performed in this study to investigate the effects of temperature on bacterial
density and activity and the MICP processes occurring at different temperatures
(4-50{\deg}C). Spatial and temporal variations in the formation and development
of calcium carbonate precipitates, including their amount, type, growth rate,
formation, and deformation characteristics, were monitored. Results show that
different types of calcium carbonate precipitates with varying sizes and
quantities were produced by varying the temperature. Low temperature (4{\deg}C)
did not reduce bacterial activity, but limited the final amount of cementation;
low temperature reduced bacterial growth and attachment ratio, as well as
calcium carbonate precipitation rate. High temperature (50{\deg}C) conditions
significantly reduced bacterial activity within a short period of time, whilst
a repeated injection of bacteria before every two injections of cementation
solution increased the final amount of cementation. The findings made from this
paper provide insight into how MICP processes vary across a range of
temperatures and could be valuable for optimising the MICP process for
different applications.
