Wetland technology for the treatment of HCH-contaminated water - Case study at Hajek site

Prévia do material em texto

Science of the Total Environment 930 (2024) 172660
Available online 20 April 2024
0048-9697/© 2024 Published by Elsevier B.V.
Wetland technology for the treatment of HCH-contaminated water – Case 
study at Hajek site 
Miroslav Černík a,*, Jan Němeček a, Martina Štrojsová a,b, Pavla Švermová c, Tereza Sázavská a, 
Petr Brůček d 
a Institute for Nanomaterials, Advanced Technologies and Innovation, Technical University of Liberec, Studentská 2, 461 17 Liberec, Czech Republic 
b Faculty of Science, Humanities and Education, Technical University of Liberec, Studentská 2, 461 17 Liberec, Czech Republic 
c Faculty of Economics; Technical University of Liberec, Studentská 2, 461 17 Liberec, Czech Republic 
d DIAMO s.p., Správa uranových ložisek, 28. října 184, 261 01 Příbram, Czech Republic 
H I G H L I G H T S G R A P H I C A L A B S T R A C T 
• The HCH removal efficiency of 
Wetland+ ranged from 53.5 % to 96.9 
%. 
• Variation of the removal efficiency was 
mainly related to variation in flow rate. 
• Removal efficiency for individual HCH 
isomers exhibited trend: α = γ = δ > β 
= ε. 
• Improved quality of the recipient resul-
ted in increase in biodiversity of 
Diatoms. 
• Sustainability assessment showed that 
Wetland+ outranked conventional 
WWTPs. 
A R T I C L E I N F O 
Keywords: 
Hexachlorocyclohexane 
Lindane 
Biodegradation 
Constructed wetland 
Natural remediation, phytobenthos 
Diatoms 
Bioindicators 
A B S T R A C T 
Hexachlorocyclohexanes (HCH) isomers and their transformation products, such as chlorobenzenes (ClB), 
generate severe and persistent environmental problems at many sites worldwide. The Wetland technology 
employing oxidation-reduction, biosorption, biodegradation and phytoremediation methods can sufficiently 
treat HCH-contaminated water. The treatment process is inherently natural and requires no supplementary 
chemicals or energy. The prototype with a capacity of 3 L/s was installed at Hajek quarry spoil heap (CZ), to 
optimize the technology on a full scale. The system is fed by drainage water with an average concentration of 
HCH 129 μg/L, ClB 640 μg/L and chlorophenols (ClPh) of 16 μg/L. The system was tested in two years of 
operation, regularly monitored for HCH, ClB and ClPh, and maintained to improve its efficiency. The assessment 
was not only for environmental effects but also for socio and economic indicators. During the operation, the 
removal efficiency of HCH ranged from 53.5 % to 96.9 % (83.9 % on average) depending on the flow rate. 
Removal efficiency was not uniform for individual HCH isomers but exhibited the trend: α = γ = δ > β = ε. The 
improved water quality was reflected in a biodiversity increase expressed by a number of phytobenthos (diatoms) 
species, a common biomarker of aquatic environment quality. The Wetland outranked the conventional WWTP 
* Corresponding author at: Technical University of Liberec, Studentská 2, 461 17 Liberec, Czech Republic. 
E-mail address: miroslav.cernik@tul.cz (M. Černík). 
Contents lists available at ScienceDirect 
Science of the Total Environment 
journal homepage: www.elsevier.com/locate/scitotenv 
https://doi.org/10.1016/j.scitotenv.2024.172660 
Received 15 January 2024; Received in revised form 10 April 2024; Accepted 19 April 2024 
mailto:miroslav.cernik@tul.cz
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Science of the Total Environment 930 (2024) 172660
2
in 10 out of the 15 general categories, and it is the most relevant scenario from the socio, environmental, and 
economic aspects. 
1. Introduction 
HCH isomers (α, β, γ, δ, ε) and their transformation products, such as 
ClB generate severe and persistent environmental problems at many 
sites worldwide. α, β and γ-HCH are listed under the Stockholm 
Convention on persistent organic pollutants (POPs), and the use of 
γ-HCH (lindane) was banned in Europe from the end of 2007 under EC 
Regulation No.850/2004. Many studies suggest that HCH production 
across Europe has led to >40 megasites, with the total HCH waste 
exceeding 250 thousand tons (Vijgen and International HCH and Pes-
ticides Association, 2006; Vijgen et al., 2019). In recent decades, 
research has therefore focused on the study of biological, chemical and 
physical methods for treating HCH-contaminated water and soil. 
Among chemical agents, ZVI is recognized for its ability to chemi-
cally decompose HCH. Recently, there has been significant interest in 
utilizing ZVI for HCH remediation, whether in its nano-scale (nZVI; 
Elliott et al., 2008; Soukupova et al., 2015), micro-scale (μZVI; Elliott 
et al., 2009), or macro-scale (mZVI; Lacinová et al., 2013) forms. 
Lacinová et al. (2013) demonstrated that various HCH isomers were 
degraded by nZVI at different efficiencies (α = γ > β > δ > ε). Benzene 
and chlorobenzene are the end products of γ -HCH degradation under 
both anaerobic and aerobic conditions using stabilized nZVI (Wang 
et al., 2009). 
Regarding biological degradation, HCH can be degraded by anaer-
obic bacteria belonging to Clostridium sp., Citrobacter sp., Desulfovibrio 
sp., Desulfococcus sp., and Dehalobacter sp. The primary responsibility for 
aerobic degradation of HCH isomers to less chlorinated benzenes and 
benzene lies with aerobic bacteria, including genera Bacillus, Escherichia, 
Pseudomonas, Rhodanobacter, Sphingobium, Sphingomonas, and Strepto-
myces. Some species, such as Sphingobium, are capable of complete HCH 
mineralization (Badea et al., 2011; Boyle et al., 1999; Lal et al., 2010; 
Qiao et al., 2020; Semerád et al., 2023). 
Organic matter in soil and sediment has a relatively high sorption 
capacity for adsorption of HCH isomers, which reduces their mobility in 
the environment. This capability, expressed as the octanol/water 
partition coefficient (Kow) values, decreases from δ > α = β > γ (Xiao 
et al., 2004). 
Constructed wetlands are designed ecosystems where phytor-
emediation processes are promoted. Phytoremediation utilizes plants 
and root microbiomes to degrade, immobilize, or accumulate contami-
nants (Pilon-Smits, 2005; Vaněk et al., 2017; Vangronsveld et al., 2009). 
The mechanisms are rhizofiltration, rhizodegradation, phytofiltration 
and extraction, phytoimmobilization, phytostabilization, phytode-
gradation, and phytovolatilization (Arthur et al., 2005; Pilon-Smits, 
2005; Vaněk et al., 2017; Košková et al., 2022). The choice of plant 
species for a constructed wetland depends on several factors, including 
the type of water to be treated, the local climate, and the specific 
treatment goals (Shelef et al., 2013). The most common plants used in 
constructed wetlands include genera Typha, Scirpus (Schoenoplectus), 
Phragmites, Juncus and Eleocharis (Vymazal, 2013). 
The proposed Wetland system comprises three sequential steps: 1) 
permeable reactive modules filled with macro-scale zero-valent iron 
(ZVI), 2) a biosorption/biodegradation module and 3) an aerobic 
wetland module. The treatment process is inherently natural and re-
quires no supplementary chemicals or energy. The system was previ-
ously tested on-site at a small scale, with a flow rate of 90 %. 
This paper thoroughly examines the Wetland technology, a novel 
integrated approach designed to tackle HCH contamination through 
remediation mechanisms, including chemical decomposition, sorption, 
biodegradation, and phytoremediation. These mechanismsare stimu-
lated within a three-stage system, including a permeable reactive barrier 
with ZVI filling, a biosorption/ biodegradation module, and an aerobic 
wetland, as detailed in Section 2.1. 
Traditionally, the efficiency of a treatment technology is evaluated 
based on the relative removal of contaminants. Additionally, long-term 
monitoring of changes in the composition of benthic diatom commu-
nities, among others, can be a suitable tool to assess the impact of 
treatment technology on restoring the environmental functions of water 
bodies. Benthic diatoms, microscopic unicellular algae (Bacillar-
iophyceae), are common in almost all types of water. Because they are 
sensitive to and affected by various environmental factors, they are 
common indicators of water quality. 
It has also been suggested that diatoms can be used as good in-
dicators of pesticide pollution in water (Morin et al., 2009; Rimet and 
Bouchez, 2011). Several authors have studied how pesticides affect di-
atoms (Goldsborough and Robinson, 1986; Pérès et al., 1996; Berard 
et al., 2004; Schmitt-Jansen and Altenburger, 2005; Debenest et al., 
2008; Rimet and Bouchez, 2011). The effect of pesticides on diatoms can 
be different, e.g. maleic hydrazide caused an increase in deformed 
diatom frustules (Debenest et al., 2008), and diuron, azoxystrobin, and 
tebuconazole affected diatom life forms (Rimet and Bouchez, 2011). 
There is only a little information in the literature about the effect of HCH 
on diatoms, but it is known that diatoms can accumulate HCH 
(Łukowski and Ligowski, 1987; Bystrzejewska et al., 1993; Lukowski 
et al., 1997). 
2. Materials and methods 
2.1. The site 
The project’s pilot site is the former uranium mine and its spoil heap 
in Hajek, located in the western part of the Czech Republic (50◦17′31.5″ 
N 12◦53′35.2″ E). In the 1960s (until 1971), uranium was mined on the 
site. The overlying soil was dumped in a nearby spoil heap. Between 
1966 and 1968, the state authorities decided to dispose of about 
3000–5000 t of the ballast HCH isomers and waste ClB from the 
chemical production of lindane (γ-HCH) there. These substances were 
placed in various parts of the spoil heap in drums, paper packaging, or 
bulk. 
Later, the spoil heap was dewatered by the construction of a drainage 
system consisting of subhorizontal wells. Since January 1989, HCH 
isomers and ClB have been monitored and documented at the drainage 
system outlet and its recipient - the Ostrovský Creek. Nowadays, the 
long-term average concentrations of HCH, ClB and ClPh at the drainage 
system outlet are 129 μg/L, 640 μg/L, and 16 μg/L, respectively. 
2.2. The wetland technology 
Based on the pilot project results, a full-scale system was designed 
and installed within the EU LIFE project LIFEPOPWAT in 2021. The 
system (Fig. 1) has four sections. The inlet section (section A) collects 
water from individual subhorizontal wells of the Hajek spoil heap and 
feeds the subsequent reactive compartments. Three parallel branches 
form the permeable reactive barrier (module B), each comprising two 
basins in series. The basins were filled with ZVI. Here, the treated water 
loses dissolved oxygen and gains a low redox potential (ORP) necessary 
for HCH dechlorination. In this step, the most persistent β- and ε-HCH 
M. Černík et al. 
Science of the Total Environment 930 (2024) 172660
3
isomers (among other isomers) are decomposed. The total area of 
module B is 540 m2 and the total volume is 360 m3. The iron chips have a 
relatively high porosity of 45 %; therefore, the total volume of water is 
approximately 160 m3. The residence time of water in module B is 
approximately 15 h in case of all three parallel branches operation and 
10 h in case of two (for the flow rate of 3 L/s). 
The treated water continues to the two parallel compartments – the 
biosorption modules (modules C), filled with a mixture of peat (40 %), 
crashed stones (30 %), loamy soil (20 %) and wooden chips (10 %). Reed 
canary grass (Phalaris arundinacea) and common reed (Phragmites aus-
tralis) were planted there. The total area of the tanks is 650 m2, and the 
total water volume is 115 m3. The residence time of water in this 
compartment is approximately 10 h (for the flow rate of 3 L/s). Massive 
precipitation of Fe oxyhydroxides occurs on the substrate surface in 
modules C, resulting from the change in redox conditions from module B 
to C. 
The aerobic wetland system (module D) is the final treatment step. 
The wetland is characterized by a high biodiversity of plants partly 
reintroduced from the surrounding wetland reserves and adjacent na-
ture. The most represented species in module D are the macroscopic alga 
Chara sp. and wetland plants Glyceria fluitans, Juncus articulatus, J. 
effusus, Scirpus sylvaticus, Spargamium erectum, and Typha latifolia. 
The aerobic wetland system consists of one compartment with a total 
area of 2700 m2 and a water volume of 700 m3. The water level is limited 
to a maximum of 25 cm. The bottom of the wetland was filled with 
loamy soil (50 %), crashed stones (30 %), compost (10 %), and wooden 
chips (10 %). This module serves for the final removal of organic sub-
stances, suspended substances, and decomposition products of HCH, 
especially chlorobenzenes. The residence time of water in this 
compartment is approximately 65 h (for a flow rate of 3 L/s). 
2.3. Sampling 
The water samples for chemical analyses were collected at outflows 
of each Wetland module. The physical-chemical parameters of water 
were measured directly on-site by temperature, pH, electrical conduc-
tivity, redox potential, and dissolved oxygen concentration WTW probes 
connected to the Multi 3430 SET C (WTW, Weilheim, Germany). All 
samples were transported to the laboratory in a cooled box. Water 
samples for dissolved metals were filtered through a 0.45 μm membrane 
filter and fixed by HCl in the field. 
Diatom samples were collected along the Ostrovský Creek, the 
recipient of the system outflow (Fig. 2), in August 2021 (before the 
Wetland prototype commissioning), in August 2022 and August 2023 (i. 
e., approximately a year and two years after commissioning) as well as in 
the modules of the Wetland treatment system in August 2022 and 
August 2023. An uncontaminated tributary of the Ostrovský Creek was 
chosen as a reference point (the Reference Creek in Fig. 2) and sampled 
in August 2021 and August 2023 (in August 2022, the creek was dry). 
Diatom samples were taken from submerged stones, from various sur-
faces (submerged plants, leaves, and branches of trees and shrubs), and 
from the mud surface layer with fine detritus when no stones or plants 
were present. Samples were taken in 100 mL plastic bottles and trans-
ported to the laboratory in cool and dark conditions. Once in the labo-
ratory, a microscopic analysis of live samples was performed, and 
permanent slides of diatoms were prepared. The remaining samples 
were preserved with formaldehyde solution to a final concentration of 3 
% and archived. 
2.4. Chemical analyses 
The concentration of HCH isomers, ClB and ClPh, in water was 
determined using two GC–MS assemblies according to Wacławek et al. 
(2019) method. HCH, ClB and ClPh were measured by the RSH/Trace 
1310/TSQ 8000 Evo GC–MS array (ThermoFisher Scientific, USA) with 
a Scion-5MS column for HCH and ClB (Scion Instruments, Goes, The 
Netherlands) and benzene and monochlorobenzene by the CombiPal/ 
CP3800/Saturn2200 RSH/Trace 1310/TSQ 8000 GC–MS array (PAL, 
Zwingen, Switzerland; Varian, Palo Alto, ThermoFisher Scientific USA) 
using a DB-624 Rxi-624Sil Ms. (Restek, USA) column (Agilent, Santa 
Clara, USA). Samples were extracted using the headspace SPME tech-
nique, either with a PDMS/DVB fibrewith a coating thickness of 100 μm 
(Supelco, Bellefonte, USA) or via direct injection of the sample in static 
headspace mode. Before extraction, samples were derivatized to form 
acetylated chlorophenols (following EN 12673). Isotopically labelled 
compounds (γ-HCH D6, pentachlorophenol 13C6, 1,3,5-trichloroben-
zene D3, toluene D8) were used as internal GC–MS/MS analysis 
standards. 
Concentrations of dissolved calcium (Ca), magnesium (Mg), sodium 
(Na), potassium (K), iron (Fe) and manganese (Mn) were measured by 
an Optima 2100 inductively coupled plasma optical emission spec-
trometer (ICP-OES; Perkin Elmer, USA), according to standard proced-
ure ČSN EN ISO 11885 (2007); chloride (Cl− ), nitrate (NO3
− ) and 
sulphate (SO4
2− ) by ion chromatography (type Dionex ICS-2100, Thermo 
Fisher Scientific, USA) according to ČSN EN ISO 10304-1 (2007); and 
bicarbonate (HCO3
− ) and carbonate (CO3
2− ) by titration according to ČSN 
EN ISO 9963-1 (1994). Quality control procedures for the chemical 
analyses followed requirements for the laboratory accredited according 
to norm ČSN EN ISO/IEC 17025:2018. 
2.5. Diversity of benthic diatoms 
The diatom species’ determination and diatom valves’ counts were 
processed by permanent slides using a light microscope (Optika, B- 
383PL, Italy) equipped with a camera (Optika, C–B1, Italy) at a 
magnification of 1000. Diatom taxa were identified using standard 
literature (Lange-Bertalot et al., 2017). The relative abundance of di-
atoms (the proportional representation of different diatom taxa within 
the community) was evaluated by enumeration of frustules. The number 
of given species was obtained by calculating individuals in a random 
sample in the ocular fields of a microscope. A minimum of 300 diatom 
valves were counted in each sample. In samples of a few individuals 
(〈300), all frustules on two permanent slides were counted. The relative 
abundance data were assigned to seven abundance classes as follows: 0 
= 0 % (absent), 1 ≥ 0 toof individual modules of the 
Wetland prototype are shown in Supplementary Fig. S1. Modules B3 +
B4 have been in operation for a shorter period (since April 2023) and 
were fed by an individual subhorizontal well with a low flow rate, i.e. 
there is a significantly longer water residence time in these modules. 
Therefore, their removal efficiency cannot be compared to one of the 
other B modules and thus is not displayed in the graph. Modules B1 + B2 
and B5 + B6 exhibited similar HCH removal efficiencies of 46 % and 45 
%, respectively. The highest efficiency of 52 % was observed in module 
D, with an increasing trend over time due to the gradual growth of 
wetland plants. Biosorption modules C1 and C2 showed the lowest 
removal rates of 34 % and 25 %, respectively. However, these modules 
are significantly smaller than module D, where the residence time is 
approximately six times longer. It is also essential to notice that the ef-
ficiencies of downgradient modules are affected by the performance of 
upgradient ones. 
The removal efficiency was not uniform for individual HCH isomers 
but exhibited the trend: α = γ = δ > β = ε as shown in Fig. 4a. This trend 
changed the isomer profile of HCH. While δ-HCH isomer dominated the 
inflow, ε-HCH prevailed in the outflow from the Wetland system. 
However, the trend is not the same in the individual modules of the 
Wetland. In modules B (permeable reactive barrier), there is a small 
difference in the removal of HCH isomers (e.g. in modules B5 + B6 from 
34 % for ε-HCH to 47 % for δ-HCH). On the contrary, in biosorption 
modules C1 and C2 and also in module D, lower removal efficiencies 
were observed for β-HCH and ε-HCH isomers in comparison to other 
α-HCH, γ-HCH and δ-HCH, as shown in Fig. 4b. These results support the 
irreplaceable role of HCH chemical reduction in module B for the 
removal of the persistent β-HCH and ε-HCH. 
Fig. 3. HCH total removal efficiency (%) and the flow rate (L/s) as a function of time during the test period. 
Fig. 4. a) Overall removal efficiency of HCH isomers. The mean standard de-
viation for all isomers was 18 %; b) Average removal efficiency of individual 
HCH isomers in modules of the Wetland prototype. The mean standard devia-
tion for all isomers and modules was 24 %. B1 + B2 are the B1 and B2 reactive 
permeable modules in series, similarly for B5 + B6. C1 and C2 are biosorption 
modules in parallel. Module D is an aerobic wetland. 
M. Černík et al. 
Science of the Total Environment 930 (2024) 172660
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The results can be compared with those of other authors to a limited 
extent, as a similar full-scale system has not yet been installed. Chen 
et al. (Chen et al., 2021) investigated β-HCH removal using vertical-flow 
constructed wetlands with different vegetation plantations (Acorus 
calamus, Canna indica, Thalia dealbata, and Pontederia cordata). Their 
efficiency in a small laboratory and full-controlled system was between 
90.86 and 98.17 % but for the much lower β-HCH concentration of 10 
μg/L. Yang et al. (Yang et al., 2022) investigated the fate of HCH and 
dichlorodiphenyltrichloroethane (DDT) in laboratory-scale constructed 
wetlands. The results showed that substrate adsorption (50.55 %–72.74 
%) and microbial degradation (20.38 %–27.89 %) were the main ways 
to remove OCPs. 
3.4. Mass of eliminated pollutants 
The cumulative eliminated mass of HCH and its co-contaminants ClB 
and ClPh were calculated. In 27 months of test operation, the Wetland 
prototype removed approximately 12.8 kg of HCH, 68.5 kg of ClB, 1.2 kg 
of ClPh, and about 2.0 tons of Fe and 212 kg of Mn. 
3.5. HCH mass discharge into the Ostrovský Creek 
The recipient of the dump leachate – the Ostrovský Creek, is a sen-
sitive watercourse as it feeds the Horní and Dolní ̌Stít ponds used for carp 
fish breeding. Before the test operation, HCH mass discharge to 
Ostrovský Creek was between 23 and 25 g/day based on two monitoring 
campaigns performed in April and August 2021. During the whole test 
operation, the HCH mass discharge dropped to 0.3–11.3 g/day (a 
decrease of 51–99 %); see Fig. 5. 
3.6. Diatom diversity 
As depicted in Fig. 6, before the Wetland commissioning (2021), 0 to 
35 species were identified in individual profiles of the Ostrovský Creek. 
Shannon diversity index (H) ranged from 0 to 4.72. There was a general 
increase in the number of species and the Shannon diversity index in the 
direction of surface water flow, obviously due to dilution and attenua-
tion processes that resulted in a gradual decrease in HCH concentration 
from 86.53 μg/L (in profile 1) to 6.91 μg/L (in profile 4). 
In the years 2022 and 2023, significant increases in number of spe-
cies and the Shannon diversity index were observed in profiles 1 and 2 of 
the Ostrovský Creek. In profile 1, the most affected by a discharge of 
HCH containing dump leachate, the number of diatom species increased 
from 0 to 25 and the Shannon diversity index from 0 to 3.62 within two 
years of Wetland operation. As the HCH mass flux into the Ostrovsky 
Creek decreased from the initial value of 23 to 25 g/day to 3.3 g/day on 
average, the increase in diatom biodiversity is an obvious consequence 
of improved surface water quality. 
In downgradient profiles 3 and 4, the number of diatom species and 
the Shannon diversity index showed no noticeable increase. Due to 
natural attenuation processes and sorption, the HCH concentration was 
decreasing along the flow of the Ostrovský Creek even before the 
Wetland operation, and diatom diversity in profiles 3 and 4 was 
comparable. 
The most frequently occurring diatom species in the Ostrovský Creek 
in all three monitoring campaigns were Gomphonema parvulum, Cymbella 
lange-bertalotii, Navicula lanceolata and Nitzschia linearis. The species 
with the highest relative abundance in the reference creek were Eunotia 
arcus, E. botuliformis and Gomphonema parvulum. Both Eunotia arcus and 
E. botuliformis in the reference creek prefer undisturbed, oligotrophic 
and electrolyte-poor freshwater habitats. These species never dominated 
in the Ostrovský Creek. 
Regarding the diatoms in the Wetland prototype, 34 species were 
found in August 2022. The highest number of species (18) was detected 
in section D3 of module D, and no diatoms were observed in the inlet 
sections C1/1 and C2/1 of parallel modules C. Similarly, the Shannon 
diversity index (H) exhibited an increasing trend along the direction of 
water flow from 0 in sections C1/1 and C2/1 to 3.55 in section D4 
(Fig. 7). 
In August 2023, most profiles observed a noticeably higher number 
of diatom species and values of the Shannon diversity index (H). The 
number of diatom species ranged from 5 (section C2/1) to 26 (section 
D4). Correspondingly, the Shannon diversity index increased to a level 
ranging from 0.49 (section C2/1) to 2.66 (section D4). The most 
frequently occurring species in the Wetland prototype were Cymbella 
lange-bertalotii, Achnanthidium minutissimum, Rhopalodia parallela and 
Fig. 5. HCH mass discharge into the Ostrovský Creek (g/day) as a function of time before and during the test. 
M. Černík et al. 
Science of the Total Environment 930 (2024) 172660
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Nitzschia linearis. Cymbella lange-bertalotii was the most resistant species, 
dominating sections C, with the highest HCH concentrations. 
3.7. Sustainability of remediation 
The three alternative water treatment scenarios regarding con-
struction and operation were compared comprehensively for the 
selected relevant environmental,economic, and social criteria. The 
ranked answers were plotted as radar graphs in Fig. 8. In this qualitative 
assessment, Wetland outranked the use of conventional WWTP for 10 
out of 15 general categories, and where it did not outrank, the ranking 
was very similar. In only one category, uncertainty and evidence, did it 
rank behind WWTP, which was entirely predictable for an emerging 
technology compared to an established one. Another result is that while 
the experts in the team mostly agreed in their assessment of the sce-
narios, the external assessors often had very conflicting views, 
depending on their professional interests. The more comprehensive 
consultation provides useful validation for supporting an approach to 
environmental restoration projects. 
4. Conclusions 
The Wetland demonstration prototype has treated drainage water 
heavily contaminated by HCH since its commissioning for 809 days 
(~27 months). During this test operation, the average removal effi-
ciency of HCH, ClB and ClPh was 83.9 %, 95.4 % and 79.4 %, respec-
tively. The efficiency of the HCH removal was lower than expected due 
to higher water flows (over the design capacity of 3 L/s). This efficiency 
will increase in future with the growth of the wetlandś plants. Removal 
for individual HCH isomers exhibited a higher efficiency for α, γ and δ 
than for β and ε. Consequently, while δ-HCH isomer dominated the 
inflow, ε-HCH prevailed in the outflow from the Wetland prototype. 
Regarding removal efficiencies of individual Wetland modules, the 
highest efficiency of 52 % was observed for module D (aerobic wetland), 
which has an increasing trend, most likely due to the gradual growth of 
wetland plants. 
Consequently, the HCH mass discharge to the Ostrovsky Creek 
decreased from about 24 g/day to 0.3–11.3 g/day, marking an 
approximate 51 % to 99 % decrease, depending on the flow rate. Within 
the test operation period, the Wetland prototype treated approximately 
130,800 m3 of contaminated water and removed about 12.8 kg of HCH, 
68.5 kg of ClB, 1.2 kg of ClPh, 2.0 tons of Fe and 212 kg of Mn. The water 
quality in Ostrovsky Creek was improved, reflected in increased biodi-
versity determined by phytobenthos (diatoms). 
The sustainability assessment showed that Wetland technology is the 
most suitable solution, both environmentally, socially, and 
economically. 
Funding 
This work was supported by the EU Life Programme under the 
project LIFEPOPWAT (No. LIFE18 ENV/CZ/000374). 
Fig. 6. Number of diatom species and the Shannon diversity index (H) in the Ostrovský Creek and the reference creek. 
Fig. 7. Number of diatom species and the Shannon diversity index (H) in the 
modules C and D of Wetland. 
M. Černík et al. 
Science of the Total Environment 930 (2024) 172660
8
CRediT authorship contribution statement 
Miroslav Černík: Writing – review & editing, Supervision, 
Conceptualization. Jan Němeček: Writing – original draft, Conceptu-
alization. Martina Štrojsová: Writing – original draft, Methodology. 
Pavla Švermová: Investigation, Data curation. Tereza Sázavská: 
Formal analysis. Petr Brůček: Investigation. 
Declaration of competing interest 
The authors declare no conflict of interest. The funders played no 
role in the design of the study; in the collection, analysis, or interpre-
tation of data; in the writing of the manuscript, or in the decision to 
publish the results. 
Data availability 
Data will be made available on request. 
Appendix A. Supplementary data 
Supplementary data to this article can be found online at https://doi. 
org/10.1016/j.scitotenv.2024.172660. 
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	Wetland technology for the treatment of HCH-contaminated water – Case study at Hajek site
	1 Introduction
	2 Materials and methods
	2.1 The site
	2.2 The wetland technology
	2.3 Sampling
	2.4 Chemical analyses
	2.5 Diversity of benthic diatoms
	2.6 Removal efficiency
	2.7 Sustainability of remediation
	3 Results
	3.1 Physicochemical parameters and chemical composition of inlet water
	3.2 Flow rate, amount of treated water
	3.3 Pollutant removal efficiency
	3.4 Mass of eliminated pollutants
	3.5 HCH mass discharge into the Ostrovský Creek
	3.6 Diatom diversity
	3.7 Sustainability of remediation
	4 Conclusions
	Funding
	CRediT authorship contribution statement
	Declaration of competing interest
	Data availability
	Appendix A Supplementary data
	References