|
|
Microbes help clean toxic waste dumps |
|
Researchers from the Florida State University (FSU), the
United States, are studying a bioremediation technology to
clean up toxic waste dump sites. Toxic wastes from weapons
manufacturing between 1951 and 1983 have been buried under 243
acres in an East Tennessee valley. These compounds have been
leaching into groundwater, extending in radioactive plumes for
miles from the contaminated site.
During the course of a forthcoming five-year study, FSU
Associate Prof. Joel Kostka and his team will test the natural
method which involves the stimulation of naturally occurring
microbes to promote bacterial growth in the soil sub-surface
that scrub it off potentially deadly radioactive metal. If the
bioremediation process proves successful on the uranium,
technetium, nitrates and other potentially lethal leftovers at
the site, the process should work to mitigate contamination at
more than 7,000 other sites nationwide and do so more
economically and effectively than most conventional methods.
The FSU researchers and other research teams from several
universities and national laboratories across the country are
involved in the clean-up project. Together, these teams will
develop models to help predict the rate at which levels of
contamination drop when using natural and artificial
remediation methods. Sub-surface changes would be closely
monitored using geophysical methods that send acoustic,
electric and other signals into the ground. Prof. Kostkas
team will lead the subsurface microbiology portion of the
project.
Website:
www.joelkostka.net
Website:
www.sciencedaily.com |
|
|
|
|
Permeable reactive barrier technology |
|
A former manufactured gas plant in Southwest England is the
site of an operational gas distribution depot. Application of
conventionally used remediation strategies was not feasible
owing to constraints posed by structures above and below the
surface. A permeable reactive barrier (PRB) specifically, a
SEquential REactive BARrier (SEREBAR) was selected as the
best remediation option for this site.
The SEREBAR is currently treating groundwater contaminated
with cyanide, polycyclic aromatic hydrocarbons and petroleum
hydrocarbons. The system comprises an impermeable bentonite
slurry barrier 200 m long installed across active gas mains to
intercept contaminated groundwater and direct it into the
capture zone of the SEREBAR system. The groundwater flows into
the system through an interceptor and six treatment canisters
that remediate the contaminated water using sequential
anaerobic and aerobic treatments populated by indigenous
bacteria. A back-up system of granular activated carbon is
provided. Monitoring of results since start-up show that the
contaminants in the discharge are significantly lower than the
negotiated clean-up levels.
Website:
www.clu-in.org |
|
|
|
|
Bioremediation for petroleum soil/water
contamination |
|
CW3M Co. Inc., the United States, has patented methods and
compositions that facilitate site-specific bioremediation of
groundwater and soil with petroleum contamination. In situ
bioremediation involves injecting a biomass including
micro-organisms and associated nutrients, minerals and
co-solvents directly into the groundwater or soil
contaminant plume in strategic locations based on geophysical
site characteristics of the sites subsurface. As the biomass
slurry comes in contact with the contaminant, degradation
begins. The micro-organisms trans-form ingredients of the
slurry, plus nutrients from the environment, into
cell-building materials and extracellular by-products such as
water and carbon dioxide.
The concentration of the individual indigenous micro-organism
strains and their relative percentages vary with the
concentration of the pollutants in the soil and groundwater.
Also, the rate of biodegradation is proportional to the types
and concentration of the bacteria available to do the work.
Under normal conditions, the bacteria will double as
frequently as every 15-20 min until they reach a population of
several billion per gram of soil. This method is suitable for
contamination resulting from kerosene, diesel oil, fuel oil or
petrol, with the total petroleum hydrocarbons being below
50,000 ppm. The hydraulic conductivity of the site has to be
greater than 10-7 cm/s.
Website:
www.freepatentsonline.com |
|
|
|
|
Fungal strain aids bioremediation |
|
Researchers in Egypt have isolated a fungal strain that
exhibits high affinity to adsorb and degrade crude petroleum
oil. Nutritional and environmental factors that affect
petroleum degradation were evaluated by applying
Placketl-Burman design, where K2HPO4, inoculum size and pH
were the most significant variables. To optimize the level of
the significant factors, Box-Behnken design was carried out
and a mathematical model created. Further, a maximum petroleum
oil degradation of 98.8 per cent has been proved.
Contact: Mr. Gaballa/Mr. Hussein/Mr. Abdel-Fattah, Mubarak
City for Scientific Research & Technology Applications, New
Borg El-Arab City, Alexandria 21934, Egypt.
Website:
www.wipo.int
|
|
|
|
|
Enhanced control of in situ bioremediation |
|
Gas Technology Institute, the United States, has patented
method for the removal of volatile and semi-volatile
contaminants from groundwater. In this process, the
contaminants are stripped from the groundwater by sparging
with an inert carrier gas. The stripped contaminants are then
transported to a bioactive zone into which at least one
gaseous oxidant and one nutrient are independently injected,
to stimulate at least one microbial culture associated with
the bioactive zone to remove the stripped contaminants from
the bioactive zone.
By decoupling the sparging of the groundwater from the
introduction of oxidants and nutrient feed gases into the
bioventing bioactive zone of the subsurface, the oxygen and
nutrient inputs to the bioactive zone can be adjusted (or
carburetted) and controlled independently from the hydrocarbon
input to the bioactive zone to achieve good kinetic
performance in the bioactive zone while avoiding the problems
of plugging of groundwater sparging due to biofilm and
precipitate formation.
Website:
www.freepatentsonline.com
|
|
|
|
|
Vermiculture for eco-friendly remediation |
|
Researchers at the Institute for Ecosystem Studies, Italy,
have studied, in laboratory scale, the effects of some
bioremediation treatments on polluted soil and the use of
specific parameters to study the evolution of biochemical
processes that take place during soil decontamination. The
bioremediation treatments were: compost; compost plus
earthworm, Eisenia fetida; and a cocktail of micro-organisms,
enzymes and nu-trients. Soil without treatment was used as the
control.
Chemical, physico-chemical, biolo-gical and biochemical
parameters were determined to assess the efficiency of the
processes involved in the degradation of hydrocarbons.
Investigations revealed an intense microbiological activity
expressed as carbon dioxide (CO2) generation. The two compost
treatments had the highest CO2 release, indicating the
availability of organic substrate characterizing the compost.
The organic substrate reduction decreased hydrolytic enzyme
activities representative of carbon (-glucosidase), nitrogen
(protease) and phosphorus (phosphatase) cycles. The enzyme
activities showed their highest values in the treatments with
compost. The greatest hydrocarbon reduction was found in the
treatments with compost, particularly with earthworms.
Contact: Dr. Grazia Masciandaro, Institute for Ecosystem
Studies, Soil Chemistry Research Unit, Via Moruzzi 1, 56124
Pisa, Italy. Tel: +39 (50) 3152 481; Fax: +39 (50) 3152473
E-mail:
grazia.masciandaro@ise.cnr.it
Website:
www.ingentaconnect.com
|
|
|
|
|
Bioremediation of water with chemical
contamination |
|
Shell Oil Co., the United States, has developed a process and
apparatus for the in situ bioremediation of aquifers
contaminated with chemicals, particularly oxygenated chemicals
such as MTBE and t-butyl alcohol (TBA). The process involves
injecting a microbial culture into the aquifers to degrade the
said chemicals. The process uses:
- A bacterial culture for the aerobic degradation of
target chemicals
- An apparatus for continuously or intermittently
delivering bacterial culture to the sub-surface without
backflow of soil and other materials; and
- An oxygen delivery system that injects an
oxygen-containing gas at a pressure of at least 5 psig above
the hydrostatic pressure at each delivery point, by pulsed
injection, at a frequency range of one per week to 10 per
day.
Website:
www.freepatentsonline.com
|
|
|
|
|
Rhizosphere remediation process |
|
Researchers at Han-Yang University in the Republic of Korea
have developed a process for treating soils contaminated with
explosive materials like TNT or DNT. The low-cost and
high-efficiency enhanced rhizosphere remediation technology is
different from conventional processes such as phytoremediation.
Indigenous bacteria having the ability to decompose explosives
were isolated and identified. By adding these to certain
native plants, the team developed a biological treatment
process that could effectively treat explosive-contaminated
soil. It was found that micro-organisms KT22 exhibited the
highest removal efficiency in TNT-contaminated soil, for both
liquid and solid contaminants.
Contact: Hanyang University, Republic of Korea.
E-mail:
w3master@ihanyang.ac.kr
Website:
www.hanyang.ac.kr
Website:
www.apec-vc.or.kr
|
|
|