Agriculture Reference
In-Depth Information
It has been realized that the design and operation of the MBR technology are the
key for its successful applications in water treatment. To meet the needs of different
processes, achieve further improvement in the water quality of the effluent, and
accomplish a better utilization of water resources, MBR is often combined with
other traditional methods. For example, MBR +A/O process can improve the
removal of organic matter and NH
3
-N from sewage; MBR + aerobic/anoxic/oxic
(A/A/O) process can strengthen the performance of nitrogen and phosphorus
removal; MBR + PAC (powdered activated carbon) process can reduce membrane
fouling during operation; and MBR + efficient strain process can be used for the
treatment of refractory organic wastewater.
Cleaning is the last step in membrane technology applications. Reasonable
membrane cleaning can not only restore membrane flux effectively and improve
the efficiency of the system but can also extend the life of the membrane and reduce
investment costs as well as operation expenses. The cleaning methods applied to
MBR membrane include physical cleaning, chemical cleaning, and a combination
of both. Physical cleaning includes aeration, water rinse with a high velocity,
backwashing, ultrasonic cleaning, etc. Among them, aeration and backwashing
can be easily and automatically controlled and are more common. In addition,
shortening or extending the pumping period is also effective in reducing membrane
fouling. As a new technology developed in recent years, ultrasonic cleaning pro-
duces excessive disturbance, strong shock waves, and microjets on the membrane,
accelerating the separation of contaminants on the surface of the membrane.
However, further studies are needed to determine whether ultrasonic cleaning
produces any harmful effects on the membrane. In the past, MBR studies basically
used activated sludge and pressurized flat membrane, and the types of wastewater
were mainly sewage and fecal sewage. Currently, MBR technology is being
successfully applied in waterways sewage treatment, fecal sewage treatment, land-
fill leachate treatment, and other wastewater treatments.
12.13 Combined Use of Microorganisms and NF
for Exhaustive Drip Irrigation Water Treatment
The Israel Peres Peace Center had developed MBRs with new NF membrane
technology as the core and a supporting reclaimed water irrigation technology
model. Among them, the NF membrane products are the core of the MBR compo-
nents. When compared with the membrane flux and NaCl interception of the current
commercial NF membranes such as polypiperazine amide, cellulose acetate, and
NTR-7450 sulfonated polysulfone, those of the new NF membrane are 48 and 1.8
times higher, reaching values of 2,358 L/m
2
/h and 31 %, respectively, at the same
pressure (10 bar). Thus, application of MBR can significantly improve the effi-
ciency of sewage treatment.
