Water & Wastewater Asia May/Jun 2021

FOCUS WATER & WASTEWATER ASIA | MAY/JUNE 2021
Items Permeate Concentrate
Productivity, t/day 192 58
TDS, ppm < 100 108,000
Hardness, ppm 10 2150
COD, ppm 12 1300
Ammonia-N, ppm 0.34 85
Total Ni, ppm Non-detected 4.1
Total Cr, ppm Non-detected 13.2
Electricity consumption, kWh/ t of permeate ~4.8
Spent steam consumption, t of t of permeate ~0.3
Clean and Dry in Place cycle, days 60
Table 3. MD running data in ZLD project
Items Permeate Concentrate
Productivity, t/day 96 79
Sulfuric acid, % Non-detected 20
(Al) 2
(SO 4
) 3
, % Non-detected 20
HCl, ppm 5 11000
Oil, ppm Non-detected < 11
Electricity consumption, kWh/ t of permeate ~4.2
Spent steam consumption, t of t of permeate ~0.23
Clean and Dry in Place cycle, days 180
Table 4. MD running data in volume reduction of spent acid
employed in an industrial application in ZLD
process and water recycling of spend acid
wastewater. For the same treating capacity,
the MD is more compact than MED and
MVR, and OpEx is much lower than those
of MED and MVR because it utilises lowgrade
heat or surplus heat such as spent
steam and hot water; the recovered water
can be reused in respective manufacturing
processes and productivity is easily adjusted
according to needs of downstream process.
Wetting channel design of the CSRE MD
substantially elongates the Clean and Dry
in Place cycle, which makes the CSRE
MD more feasible in practical industrial
applications.
References
Gao, Y., Shanmugasundaram, T., Wang, M., Singh, G. and Prince,
J. (2017) Membrane Distillation (MD) Based Zero Liquid Discharge
(ZLD) System. 8th IWA Membrane Technology Conference &
Exhibition for Water and Wastewater Treatment and Reuse.
Singapore.
Gao, Y., Shi, Z. (2020) Techno-Economic Analysis of Membrane
Distillation in ZLD of FGD Waste Water of Coal-Fired Power Plants.
Huadian Technology 42, 25-30.
MVR with the same evaporating capacity;
the Clean and Dry in Place cycle is up to
180 days, which is due to acid property of
wastewater and wetting channel design
of MD system. In addition, the MD system
can be integrated with the diffusion dialysis
process to recover sulfuric acid: the part of
the sulfuric acid is recovered by the diffusion
dialysis process and the recovered diluted
sulfuric acid is concentrated for reuse in
manufacturing process by MD.
CONCLUSION
The developed CSRE MD systems were
Schwantes, R., Chavan, K., Winter, D., Felsmann, C. and
Pfafferott, J. (2018) Techno-economic comparison of membrane
distillation and MVC in a zero liquid discharge application.
Desalination 428, 50–68.
Thomas, N., Mavukkandy, M. O., Loutatidou, S. and Arafat,
H.A. (2017) Membrane distillation research & implementation:
Lessons from the past five decades. Sep. Purif. Technol. 189,
108-127.
Figure 4: Water recycling plant of sulfuric acid wastewater
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