At Unbok office, manager Jongki Lee guided us through the facilities and
we had an interview. The office has tackled domestic sewage from the
residential complex near the airport. During the interview, he
emphasized the burden of the increasing cost of chemical reagents and
filters. He mentioned that the price is especially burdensome these
days, as the price of raw materials increased. This could be one of the
reasons for the application of gene modification in wastewater
treatment. Gongchon and Namhyang offices have treated the same types of
wastewater as Unbok office. Three offices had similar characteristics.
From visits to four wastewater treatment offices, we acknowledged some
points to improve in wastewater treatment. In all facilities,
microorganisms are utilized for the degradation of organic matter. This
process is called activated sludge. It basically functions by
encouraging the growth of microorganisms, with altering environments for
dominantly growing different types of microorganisms at each stage. We
noticed that the distinction among microorganisms is too simple. It has
been simply distinguished depending on the preferred growth environment,
such as the aerophile and the anaerobe. We felt a necessity of strain
selection. If we select specific strains and allow to culture them
dominantly rather than pre-existing organisms, the performance will be
improved and that is the starting point of the application of gene
modification.
Basic concept: Microalgae and Consortia
In terms of strain selection, we investigated applicable methods to this
idea. Consortia between algae and bacteria were chosen as a good option.
According to prior research, better growth of both organisms can be
expected through signal and nutritional exchange. Especially, microalgae
is an ideal organism since it efficiently decreases TN, TP, and
concentration of heavy metals. (Li, 2022) and has a high content of
neutral lipids, which is a raw material of biofuel. Indeed, we found
that visited offices have just wasted cellular pellet from the activated
sludge, or they simply used it as the solid refuse fuel recovered fuel.
From the perspective of the net cost reduction, recycling the pellet to
the bio-material is an attractive option. On the other hand, we started
to doubt why microalgae are not used in the current wastewater treatment
system.
We had a meeting with prof. dr. ir. Di Wu, whose research field is
wastewater engineering. During the meeting, he answered our question:
Why are microalgae not used in Korea? He said that microalgae are not
suitable organisms for the removal of organic matters, and it demands
larger surface area to optimally culture with the sunlight, since it is
autotroph. He said microalgae is suitable for treating daily wastewater
rather than domestic and industrial wastewater. In the meeting, we also
realized that microalgae are inappropriate to apply in Korea since the
annual temperature difference in Korea is large.
Based on the accumulated knowledge from interviews, we started to
investigate whether gene modification could complement the disadvantages
of microalgae. First, it is identified that some strains living in
Antarctica synthesize antifreeze protein, which is applicable to the
Korean climate. (Gwak, 2014) Prior research also showed heterologous
gene introduction of mercuric reductase into microalgae (Huang, 2006),
which supports the removal of heavy metals. In addition, there have been
many studies to improve biomass yield through gene manipulation. Our
concept, consortia, is also a good choice to balance the performance
between the degradation of organic matter and the removal of nitrogen
and phosphorus. (Li, 2021)
Policy
In fact, the meeting with prof. Di Wu reminded us of an interview at one
of the wastewater offices. We briefly introduced our plan and the staff
advised us that convincing the Ministry of Environment is mandatory
since there is a difference of interests between the field staff and the
administrator. According to the advice, field staffs have an interest in
the secondary benefits that are not covered by the standard, such as the
degradation of microplastics. On the other hand, administrators have
only an interest to satisfy the standard of purification. Everything
else not covered does not matter to them. In addition, the current
policy restricts offices to create additive values from recycling. This
was why the valuable cell pellets were not recycled. He mentioned that
it will take a long time to convince administrators of the
implementation.
The result of gene manipulation is bound to the regulation of the use of
genetically modified organisms. The policy in Korea demands the risk
assessment to use Living modified organisms (LMO). LMO is monitored by
Korea Disease Control and Prevention Agency. In case of the wastewater
treatment, the authority will demand documents before its
implementation. (Korea Disease Control and Prevention Agency, 2021)
The required documents are below:
① Application for permission to install and operate production
process use facilities (LMO Act Enforcement Regulations, Attachment
No. 34)
② Design drawings or copies of production process use facilities
③ Documents proving the scope of production process use
facilities and rights related to their ownership or use
④
Basic design drawings of hazard prevention facilities or copies
thereof
⑤ Equipment, technical capability, manpower and safety
management regulations required for the use of LMM
⑥
Equipment, technical capability, manpower and safety management
regulations to prevent human and environmental risks of LMM
⑦
Safety Management Standards for Operation of Production Process
Utilization Facilities
After submission, Healthcare & Safety committee in the agency will
evaluate and announce the result in 60 days by issuing the permit for
installation and operation of production process use facilities.
Current biocontainment
In terms of disinfection process, wastewater treatment facilities
already had some process for biosafety. They have mainly used
chlorination or UV-radiation to purified water. We studied whether
current bio-containment system still can be used for microalgae. In
fact, microalgae has insensitive to chlorination and UV-radiation.
According to research, while 99% of bacteria in the sludge will be
killed with less 10kJ/m2 of UV-C radiation for seconds (Roeber, 1975),
over 10kJ/m2 for minutes is reported to be enough to function for
microalgae (Pfendler, 2018). In case of chlorination, it is revealed
that microalgae accelerated to grow while bacteria is inhibited to grow
at low free chlorine concentration. (Hu, 2020) From prior research, we
concluded that more secure bio-containment system or sensitive biosensor
is needed to application of gene manipulation into wastewater treatment
in the wastewater treatment offices.
Market
In the case of Gyeonggi-do Research Institute of Health and
Environment, which developed a wastewater purification system by
raising microalgae as a single unit without genetic manipulation, it
was able to reduce 50% of the electricity cost used in the existing
sewage and wastewater system, and received love calls from many
companies.
Economic value is the best drive to implement an idea. The size of the
domestic water treatment market increased by 3% for 5 years from 91
billion dollars to 106 billion dollars. One of the most grown markets,
sections of the infrastructure, and the process have shown great
improvement from 30 billion dollars to 38 billion dollars. Furthermore,
the sewage market constantly raises 5% of the investment to develop the
efficiency of sewage purification.
In the case of Gyeonggi-do Research Institute of Health and Environment,
it developed a wastewater purification system with microalgae. After the
introduction of the system, it can reduce 50% of the electricity cost
used in the existing sewage and wastewater system, and this system
became known to its potential customers. Furthermore, since ESG
management draws attention and the regulation for the environment
becomes stricter, there is a clear demand for eco-friendly sewage and
wastewater treatment process systems.
References
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