Water treatment and reuse is the key strategy to address the problems of water shortages. To facilitate communication and application of technology and research in water reclamation, the National Conference on Water Treatment and Reuse of China was held annually from 2017 by the Committee of water treatment and reuse, Chinese society for environmental sciences.

The theme of the 5th conference was water recycling and low-carbon development. The conference, held from April 16th to 18th in 2021, brought together researchers working in different areas related to water treatment and reuse from China, USA, Australia, Ireland and many other countries and regions. More than 12,00 researchers from universities, institutes and companies attended the conference.

The conference covered 20 main topics:

  • 1.

    Physical separation theory and technologies

  • 2.

    Chemical transformation theory and technologies

  • 3.

    Biological purification theory and technologies

  • 4.

    Natural treatment theory and technologies

  • 5.

    Water treatment theory and technology based on microalgae

  • 6.

    Chemical risk and control

  • 7.

    Disinfection and microbial risk control

  • 8.

    Standard and risk control of reclaimed water environment reuse

  • 9.

    Reclaimed water storage and reuse

  • 10.

    Water quality detection and water characteristic research methods

  • 11.

    Standards and policy for water quality control and water resource management

  • 12.

    New materials, reagents, and equipment for water treatment

  • 13.

    Design and intelligent operation of water treatment process

  • 14.

    Urban water system and water recycling

  • 15.

    Industrial water system and water recycling

  • 16.

    Rural water system and water recycling

  • 17.

    Pollution control and utilization of rainwater runoff

  • 18.

    Water environment constructing and regional water recycling

  • 19.

    Watershed environment remediation and water recycling

  • 20.

    Desalination technology and processes

In this special issue of Water Reuse, 10 papers that focus on cutting-edge technology and system for water treatment and reuse, were selected among papers presented at the 5th National Conference on Water Treatment and Reuse of China. This special issue is sponsored by CSCEC Scimee Sci. & Tech. Co., Ltd to cover the article processing charges.

Each of these 10 papers focuses on a certain link of water reclamation and reuse, together forming the entire chain of treatment-distribution-detection-utilization. The first six articles focus on water treatment and risk control. Zhou et al. (2021) investigate the performance and mechanism of organic pollutants degradation in a photoelectrochemical system. Yin et al. (2021) study the removal efficiencies and mechanism of atrazine degradation by peroxymonosulfate activated with CuCo2O4 nano-particles. Hu et al. (2021) present a study on diatrizoate degradation by ozone and the formation of disinfection byproducts in the sequential chlorination. Yi et al. (2021) investigate the effect of commercial probiotics immobilized by various carriers on the remediation of aquaculture water and sediment. Yu et al. (2021) design a powder-activated carbon pre-coating membrane unit as a pretreatment for ultrafiltration system to alleviate membrane fouling and improve performance. Ren et al. (2021) investigated the efficiency of micro-flocculation as a pretreatment approach in alleviating ultrafiltration membrane fouling caused by organic matters in treated wastewater.

Further, two articles are related to distribution and water quality monitoring. Xu et al. (2021) report the effects of five pipe materials on water quality deterioration of reclaimed water produced by reverse osmosis process in large pilot-scale distribution systems by long-term running tests. Mao et al. (2021) propose a potential rapid and simple method for bacterial detection in water by excitation-emission matrix (EEM) fluorescence spectroscopy.

Lastly, two articles provide new insights to water recycling and watershed environment remediation. Liu et al. (2021) study the effects of mixed irrigation using brackish water and reclaimed water on a soil-crop system. Jiang et al. (2021) analyze the effects of large-scale compound ecological engineering system on pollution control of the estuary of a lake.

This special issue deals with various problems and investigates different treatment technologies concerning water reuse. In response to the challenges of severe water shortages and the deterioration of water quality, the focus of cutting-edge technology and system for water treatment and reuse is fast-growing worldwide. Progress is needed to provide high quality reclaimed water, minimize the risks to environment and human health, and support use of non-conventional water resources.

Hu
C.-Y.
,
Ren
S.-C.
,
Lin
Y.-L.
,
Zhang
J.-C.
,
Zhu
Y.-Y.
,
Xiong
C.
&
Wang
Q.-B
, .
2021
Kinetics of diatrizoate degradation by ozone and the formation of disinfection by-products in the sequential chlorination
.
Water Reuse
11
(
4
),
560
571
.
Jiang
Y.
,
Xu
X.
,
Wu
W.
,
Wang
B.
,
Sun
Y.
,
Chen
X.
,
Shen
Z.
&
Huang
T
, .
2021
Analysis on the effect of large-scale compound ecological engineering system on pollution control of the estuary of a lake
.
Water Reuse
11
(
4
),
649
659
.
Mao
Y.
,
Chen
X.-W.
,
Chen
Z.
,
Chen
G.-Q.
,
Lu
Y.
,
Wu
Y.-H.,
&
Hu
H-Y
, .
2021
Characterization of bacterial fluorescence: insight into rapid detection of bacteria in water
.
Water Reuse
11
(
4
),
621
631
.
Yi
M.
,
Wang
C.
,
Wang
H.
,
Zhu
X.
,
Liu
Z.
,
Gao
F.
,
Ke
X.
,
Cao
J.
,
Wang
M.
,
Liu
Y.
&
Lu
M.
2021
The in situ remediation of aquaculture water and sediment by commercial probiotics immobilized on different carriers
.
Water Reuse
11
(
4
),
572
585
.
Yin
H.
,
Li
J.
,
Yan
H.
,
Cai
H.
,
Wan
Y.
,
Yao
G.
,
Guo
Y.
&
Lai
B
, .
2021
Activation of peroxymonosulfate by CuCo2O4 nano-particles towards long-lasting removal of atrazine
.
Water Reuse
11
(
4
),
542
559
.
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