RO/NFUF

CAS E STUDY
RO | UF | MBR

Wastewater Treatment
Mirassol, Brazil

Treated Municipal Sewage Achieves High-Quality Discharge Values with Toray
MBR TechnologyINTRODUCTION
Mirassol is a small city located in the countrysideof the São Paulo state in Brazil, with a populationof approximately 60,000 people. The city
produces around 175 L/ s of municipal sewage andhas treated the wastewater through conventional
WWTP. Due to population growth in recent years,
Sanessol, the concessionaire responsible for thewater supply and sewage treatment of Mirassoland part of Igua Saneamento Group, decided
to use a state of the art technology for their newWWTP, Fartura. The plant has the capacity to treat
45 l/s.
One of the plant's challenges was treating thesewage to a high-quality level to discharge it to anearby river. The regulatory agency required theoutgoing BOD to be less than 5 ppm due to theriver's low flow and minimize ecological impact.
Toray MBR technology guarantees the complete
removal of turbidity (< 1 NTU) and pathogenic
bacteria. The membrane pores have a nominal
size of 0.08 µm densely and uniformly distributed
along the surface. Combined with effective
biological treatment, Toray MBR can produce
high-quality effluent and was selected as the newplant's technology.

Table 1 — MBR System
Toray MBR model

TMR140-400DW

Membrane type

Flat Plate MBR

No. of trains

1

No. of modules

10No. of membrane elements

4000

Capacity

144m3/hFiltration Method

Gravity

Figure 1(top):one train MBR tank containing 10 Toray MBR modules

Average Flux

25.7 lmh

Figure 2(bottom): before and after operation of MBR tank

(Gravity or Permeate Pumps)

03-BR-MB3-Marissol-2022051 of 2

MBRChemicals

CASE STUDY
RO | NF | UF | MBR

Treated Municipal Sewage Achieves High-Quality Discharge Values
with Toray MBR Technology
Figure 3: Filtrate BOD and COD

PROJECT DETAILSCOD

The complete treatment scheme consists of a3 mm primary screen, followed by the aerobic
reactor and MBR tank. The MBR system iscomprised of one train with ten TMR140- 400DW
modules in parallel, capable of treating 144 cubic
meters per hour (m³/h).

BOD

80
7060

One module consists of four-element blocks
in a double-deck arrangement for 560 m² oftotal membrane area per module. The doubledeck configuration optimizes the systemfootprint, requiring only 12 meters of length and4 meters of width for the membrane tank. Theair consumption for aeration cleaning is also
equivalent to two-element blocks, further savingenergy costs. The MBR plant operates with anaverage flux of 25.7 lmh.

5040mg/L

30201000RESULTS

102030

40

50

6070

8090100DAYS

Commissioned in 2019, the Mirassol plant has anaverage influent Biological Oxygen Demand andChemical Oxygen Demand of 178 ppm and 407ppm, respectively, a typical municipal sewage
makeup in Brazil. After the commissioning phase,the MLSS has been stable at 10 g/L, with casualfluctuations. Please refer to Figure 3 for thetreated BOD and COD.
Toray flat-sheet technology helped the customer
meet very restricted legislation with simple
construction and easy operation. Toray MBR
configuration does not require a backwash
system or permeate pump. The clean-in-place
procedure without total chemical immersion
also brings easier maintenance and cost savings
compared to other MBR technologies. Today,
Mirassol city collects and treats 100% of theproduced municipal sewage.

Figure 4:TMR140-400DW MBR module by Toray featuring four element blocks in a
double-deck arrangement

TORAY INDUSTRIES, INC.
Head Office: Nihonbashi Mitsui Tower 24th Floor, 1-1, Nihonbashi-Muromachi 2 chome, Chuo-ku,
Tokyo, 103-8666, JAPANwww.water.toray+81 3 3245-4540

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All information presented herein is believed reliable and in accordance with accepted engineering practices. Toray makes nowarranties as to the completeness of this information. Users are responsible for evaluating individual product suitability forspecific applications. Toray assumes no liability whatsoever for any special, indirect or consequential damages arising from thesale, resale or misuse of its products. © 2022 Toray Industries, Inc. Subject to change without notice.

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