The present study was carried out with the
objective of integrating physical and biological methods
for the treatment of polycyclic aromatic hydrocarbons
(PAHs)-contaminated groundwater and to assess its efficiency.
The aquifer in Kirchseeon region, Germany, is
contaminated with PAHs due to product loss of tar oil
which was used in large amounts for treating the railway
sleepers produced in this area. Six pumping wells, two
recharge wells and fifteen observation wells were installed
for this study as a part of the ex situ biodegradation
treatment plant.
Zoogloea
,
Leptothrix
,
Sphingomonas
,
Novosphingobium
and
Comamonadaceae were the indigenous
bacteria that facilitated degradation of the PAHs. In the
bioreactors, 95 % of naphthalene and methylnaphthalene
and 90 % of total PAHs were removed. During this
remediation process, 700,000 m
3 of PAHs-contaminated
groundwater was purified to almost drinking water quality.
Also, 7,000 kg of dense non-aqueous phase liquid
(DNAPL) and 950 kg of PAHs were removed from the
pumped groundwater. The remediated groundwater is
recharged back into the aquifer through two recharge wells
located 600 m from the study site. The observation wells
show a decrease in contamination of up to 95 %. Thus, this
field scale study showed that using indigenous bacteria to
remediate PAHs-contaminated groundwater is a viable
option.
