Application Study of Hydraulic Turbochargers in Landfill Leachate
Treatment Systems
Tong Liu
1
, Yunguang Ji
1
, Hongtao Li
1
, Shu-qi Xue
1*
, Mike Oklejas
2
and Shouzhi Yang
3
1
College of Mechanical Engineering, Hebei University of Science and Technology ， Shijiazhuang 050018 ， China
2
Oklejas Turbo Solutions LLC, Ann Arbor, MI 48103, USA
3
Shijiazhuang Haikuojieneng Technology Co., Ltd ， Shijiazhuang 050018 ， China
*Corresponding author e-mail:
x
Keywords: Landfill Leachate Treatment, Pressure Energy Recovery, Hydraulic Turbocharger, Energy Consumption, Seal.
Abstract: Based on the two-thousand-ton per day landfill leachate treatment process, a new system with energy
recovery device was designed by using a hydraulic turbocharger to replace the circulation pump of the
existing system. Energy consumption and equipment failure rate was decreased and system stability was
improved by using hydraulic turbocharger. This study can provide a good reference for design and integration
of energy recovery systems in landfill leachate treatment process.
1 INTRODUCTION
Landfill leachate is one kind of complex organic
liquid produced in the process of landfill garbage
storage, and it will cause serious environmental
pollution if it is not treated before discharge. With
the change of filling ages, the BOD/COD5 value and
pH value of landfill leachate will increase and it is
difficult to use biochemical method merely to meet
the emission standards for the treated liquid. Reverse
osmosis (RO) process is little influenced by the
factors such as composition and temperature, and it
ensures the stability of water quality and has great
advantages in the treatment of landfill leachate with
high concentration of salt (
ZHANG Lina, 2016), so
biochemical treatment and/then RO process has
become the mainstream technology in landfill
leachate treatment. However, in the usually used disc
tube reverse osmosis (DTRO) treatment system, the
pressure energy is wasted because that the high
pressure brine is discharged through pressure release
valve directly after the first stage RO process. In this
paper, a hydraulic turbocharger is used to replace the
electric circulating pump in existing DTRO system
to recycle the brine pressure energy, which may
provide a reference for design and configuration of
energy recovery systems in landfill leachate
treatment process.
1.1 Existing Landfill Leachate DTRO
Treatment Process
As shown in Figure 1, in the current landfill
leachate treatment process, after pre-treatment,
landfill leachate is pumped through the first stage
DTRO membrane and the left brine will be
pressure-reduced by a pressure release valve and
returned the concentrated tank; the filtered liquid by
the first stage DTRO membrane is then pumped
through the second stage DTRO membrane and the
left brine in this stage will be returned back and then
pumped through the first stage membrane again.
Liquid filtered by two-stage DTRO membrane may
enter the stripping tower and tank, and can be
discharged if its quality meets the emission standard
requirements. This process has been applied in a
waste landfill of China and the measured liquid
quality data of the inlet and outlet of the system are
shown in Table 1. The operation data show that the
recovery rate of the first and second stage DTRO
membrane is 77% and 90% respectively and the
overall recovery rate of the system is 75% (
ZUO
Junfang, et al., 2011
).
Landfill leachate treatment process has high
fresh water recovery rate and low flowrate and high
pressure with the circulation brine, but the pressure
energy is not recycled and reused, and it requires
high sealing performance for circulating pumps.
110
Liu, T., Ji, Y., Li, H., Xue, S-q., Oklejas, M. and Yang, S.
Application Study of Hydraulic Turbochargers in Landfill Leachate Treatment Systems.
In 3rd International Conference on Electromechanical Control Technology and Transportation (ICECTT 2018), pages 110-113
ISBN: 978-989-758-312-4
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

Table 1: Water quality parameters of landfill leachate treatment systems.
COD
(mg.L-1)
BOD5
(mg.L-1)
SS
(mg.L-1)
NH3-N
(mg.L-1)
TN
(mg.L-1)
pH value conductivity
Inlet ≤20000 ≤6000 ≤1000 ≤2000 ≤2500 6~9 ≤20000
Outlet ≤100 ≤30 ≤30 ≤25 ≤40 6~9 -
Figure 1: The existing landfill leachate treatment process
(numbers refer to positions in Table 3).
1.2 Circulating Pump Used in the
Existing System
In the existing process, the circulating pump shown
in Figure 2 is used to pressurize the second stage
brine to return to the first stage DTRO membrane
and its inlet port pressure is 35bar, outlet pressure is
65bar, head is 300m. The high pressure of the inlet
put strict requirements for the mechanical seal of the
pump shaft connecting with the motor. High pressure
mechanical seal is expensive, and the maintenance
cost is high in the operation due to its low mean time
between failures (MTBF).
Figure 2: Internal structure of the circulation pump.
2 STRUCTURE OF HYDRAULIC
TURBOCHARGER AND ITS
APPLICATION IN DTRO
PROCESS
2.1 Structure of Hydraulic Turbocharger
As shown in Figure 3, structure of hydraulic
turbocharger is similar to that of automotive engine
turbocharger, where turbine section and pump
section are connected by a central shaft. It can be
used for pressure recovery and is widely applied in
RO desalination system. Compared with the
existing booster hydraulic turbine, hydraulic
turbocharger has the advantages of simpler structure,
higher efficiency, less leakage, and then higher
reliability and longer operation time. The
flow-through parts of the turbocharger are
calculated by one dimension method firstly, and
then key parameters are optimized by CFD
numerical simulation, finally design efficiency is
verified by experiments and testing (JI Yunguang et
al., 2017). The central bearing in pump section
bearing provides radial support, and the thrust
bearing on the turbine section is used to balance the
axial force between the turbine section and the
pump section pressure difference which points to
the turbine section. The bearing is self-lubricated so
as has more compact and simple structure. Figure 4
is the hydraulic turbocharger prototype.
In the landfill leachate treatment system, in
order to adapt to the corrosiveness of the high
salinity medium, stainless steel SS2205 is used for
the impellers and case of the turbocharger, and
polyether ether ketone (PEEK) material is used for
the thrust bearing.
Figure 3: Internal structure of the hydraulic turbocharger.
2.2 Design Parameters and Energy
Recovery Efficiency of
Turbocharger
Table 2 is the design parameters of the hydraulic
turbocharger for a two thousand ton landfill leachate
Application Study of Hydraulic Turbochargers in Landfill Leachate Treatment Systems
111

treatment system.
Table 2: Parameters of the turbocharger used in a
2000-ton/day landfill leachate treatment system.
Parameters Values
Turbine Section Flowrate, Q
T
11.3 m
3
/h
Inlet pressure of turbine section, P
t,in
6 MPa
Outlet pressure of turbine section, P
t,out
0.5 MPa
Pump section flowrate, Q
p
6.75 m
3
/h
Inlet pressure of pump section, P
p,in
3.5 MPa
Outlet pressure of pump section, P
p,out
6.5 MPa
Overall-energy-recovery-fficiency, η
32.6%
Figure 4：The prototype of the hydraulic turbocharger.
The energy recovery efficiency of the hydraulic
turbocharger can be calculated by the following
equation:
)(
-
,,
outP,inP,P
outTinTT
PPQ
PPQ
−
=
）（
η
(1)
2.3 Energy Recovery Process of
Hydraulic Turbocharger
As shown in Figure 5, in the new process the
circulating pump is replaced by hydraulic
turbocharger cycle, and the discharge pipeline is
connected to the turbocharger. The pressure energy
of the first stage brine then can be recycled and
pressure of second state can be boosted by the
hydraulic turbocharger.
Figure 5 ： Landfill leachate treatment process with a
turbocharger.
Different from the RO desalination system, the
flowrate of the first state is larger than that of the
second stage in landfill leachate treatment process,
and the available flowrate in the turbine section is
greater than that needed for the pump section.
Therefore, only a part of pressure energy in first
stage brine is used to provide pressure for the
second state circulating, then a pressure relief valve
is designed to adjust the flowrate of turbine section.
Compared with the existing system, the new system
does not require a motor to provide mechanical
energy, where the energy exchange between the first
stage and second stage brine can be performed by
the hydraulic turbocharger.
3 COMPARISON OF ENERGY
CONSUMPTION
Hydraulic turbocharger energy recovery system is
widely used in RO seawater and brackish water
desalination,, petrochemical and other
industries(Alisha Cooley, 2016). In this study,
application of hydraulic turbocharger energy
recycling device in landfill leachate DTRO
treatment system is firstly proposed in China.
Table 3 lists flowrate and pressure on each
position in the process of 2000-ton/day landfill
leachate DTRO treatment system. The energy
consumption the whole process is that of the pumps
for providing pressure:
g
Q
TH
W
=
(2)
where W is energy consumption of high pressure
pump per hour (kWh), Q is flowrate (m
3
/h), T is
time (H), H is pump lift (m), g is gravity constant.
Effective work W1 of high pressure water pump
FP is
WTHQW 147.17kg
111
== ρ
(3)
Effective work W
2
of boosting pump FP-2 is:
WTHQW 75.49kg
222
==
ρ
(4)
Effective work W
3
of circulating pump RP is
WTHQW 5.68kg
333
==
ρ
(5)
Total energy consumption per hour of the
existing system is
kWWWWW
new
292.5///
332211
=++=
η
η
η
(6)
where η
1
is the efficiency of the high pressure pump
FP; η
2
is the efficiency of boosting pump of FP2, η
3
is the efficiency of the circulation pump FP3.
Table 4 shows the flowrate and pressure of the
landfill leachate DTRO treatment system with a
hydraulic turbocharger.
ICECTT 2018 - 3rd International Conference on Electromechanical Control Technology and Transportation
112

Table 3: Flowrate and pressure of existing landfill leachate treatment process.
Position 1 2 3 4 5 6 7 8 9 10
Flowrate/
m
3
· 83.3 83.3 90.3 20.77 20.77 69.5 69.5 6.95 6.95 62.6
Pressure/MPa
0.1 65 65 60 0.5 0.1 40 35 65 0.5
Table 4: Flowrate and pressure of landfill leachate treatment process with hydraulic turbocharger.
Position 1 2 3 4 5 6 7 8 9 10 11
Flowrate/m
3
h
-
1
（
m3/h
）
83.3 83.3 90.3 20.77 11.35 69.5 69.5 6.95 6.95 62.6 20.77
Pressure/M
P
0.1 65 65 60 60 0.1 40 35 65 0.5 0.5
Energy consumed by the new system is
WWWW 278.32k//
2211new
=+=
η
η
(7)
Electricity power saved every hour
WWW 14.2k-
new
=
(8)
It is seen from the calculated results that
hydraulic turbocharger used in the new process
reduces the energy consumption by 14.2 kW or 5%
compared with the existing landfill leachate DTRO
treatment system.
4 CONCULUSIONS
A new system with energy recovery device is
presented by using a hydraulic turbocharger to
replace the circulation pump of the existing landfill
leachate system. Calculation shows that the new
system has lower energy consumption and failure
rate, and higher operation stability due to no
mechanical dynamic seals in the turbocharger. This
study can provide a good reference for integration of
hydraulic turbocharger energy recovery systems in
landfill leachate DTRO treatment system.
However, the pressure energy is not recycled
completely by the hydraulic turbocharger because
the flowrate of the second stage brine is relative low
in the two-stage landfill leachate treatment system,
in this case a electricity generator may be integrated
in the turbocharger as shown in Figure 6 (Tamer A.
EI-Sayed et al., 2016), where the extra energy can be
recycled and transformed to electricity power, which
will be presented in the future research.
ACKNOWLEDGMENTS
This work was financially supported by key project
of science and technology research of Hebei higher
Figure 6: Hydraulic turbocharger with generator.
education institutions (ZD2015090); science and
technology project of Hebei province, China
(17394505D); 100 Talents Program of Hebei
province, China (E2016100006); and introduction
of foreign intelligence project of the year 2017 of
Hebei province, China.
REFERENCES
ZHANG Lina, 2016. Process design of two-stage DTRO
system for landfill leachate treatment. China Water,
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ZUO Junfang, et al., 2011. Application of DTRO
technology in the treatment of landfill leachate.
Membrane Science and Technology, 2011,31 (02):
110-115 (in Chinese).
JI Yunguang, et al., 2017. Application study of fluid
pressure energy recycling of decarbonization
process by C4H6O3 in ammonia synthesis systems
by hydraulic turbochargers. Modern Chemical
Industry, 37 (11): 158-161 +163 (in Chinese).
Alisha Cooley, 2016. Turbocharged cost savings in RO
systems. World Pumps, 6:36-41.
Tamer A. EI-Sayed et al., 2016. Performance of hydraulic
turbocharger interated with energy management in
SWRO desalination plants. Desalination, 379:
85–92
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