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Nature-Based Solutions Using Natural Coagulants from Urban Parks as a Strategy for Intelligent Adaptation Systems to Address Sanitation and Water Scarcity in Catalonia�Infante, Nury1, Hernández del Amo, Elena2, Amante, Beatriz1, López, Victor1, Beatriz, Escribano1, Morató, Jordi1, Sánchez, Olga2�1 Polytechnic University of Catalonia, Terrassa, Spain�2 Autonomous University of Barcelona, Cerdanyola del Vallès, Spain�E-mail contact: nury.gineth.infante@upc.edu

Water stress in Catalonia

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Total coliforms

E. coli

Plant species with coagulant properties and antimicrobial activities related to sustainable water management

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FEMS MICRO Milan 2025: Congress & Exhibition

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INTRODUCTION

METODHOLOGY

RESULTS AND DISCUSSION

RESULTS AND DISCUSSION

CONCLUSIONS

REFERENCES

Phase 1

Phase 3

Phase 1

Phase 2

Phase 3

Water stress in Catalonia

Current status of urban parks (physicochemical and microbiological characterization)

Water and Sediment health

Objective

Catalonia is experiencing increasing levels of hydric stress, driven by the combined effects of prolonged droughts, rising temperatures, altered precipitation patterns, and intensified water demand, Fig 1.

Fig 1. Changes in Water Stress between January and September 2024 in Catalonia.

This critical situation directly impacts the availability of surface and groundwater resources, which are essential for all productive sectors, including ecosystem services.

In response, Nature-Based Solutions (NbS) offer a resilient, low-impact alternative by leveraging natural processes and biodiversity to address water quality and availability, Fig 2.

Fig 2. Mitigation and Adaptation Strategies for Water Conservation

Biocoagulants (Blue Economy)

Raw material: bioactive extracts (seeds, leaves, and barks)�Sustainable processes: NADES extraction�Application: sustainable water treatment

Natural coagulants derived from resilient urban represent a promising NbS for sustainable water. These plant-based biopolymers are biodegradable, effective and aligned with circular economy principles, Fig 3.

This study aims to address these challenges by evaluating the effectiveness of natural antibacterial agents and plant-based coagulants derived from species in Parc Sant Jordi, Terrassa, for potential biotechnological applications in sustainable water management. The research aligns with the European Union's "Water Smart Society" vision.

Fig 3. Valorization of Plant Species from Urban Parks for Sustainable Water Management

A total of 30 samples from 5 different sites will be analyzed (15 water samples, 15 sediment samples from five representative urban parks monitored across four climatic seasons in Catalonia, Fig 4.

Table 1. Antibiotic Groups Used for AMR Test

In-situ Parameter Analysis

Physicochemical Parameters

pH

Dissolved oxygen

Electrical conductivity

Temperature

In-vitro Parameter Analysis

Microbiological Parameters:

Group

Antibiotic

Code

Concentration (µg/mL)

Tetracycline

Tetracycline

TC

2

Minocycline

MC

2

Beta-lactams

Ampicillin

AMP

8

 Polymyxin

Ceftazidime

TZ

8

Colistin

CO

2

Sulfonamides

sulfamethoxazole

SXT

4

Antimicrobial resistance bacteria (AMR) was assessed using the following groups of antibiotics, as presented in Table 1.

Fig 4. Urban parKs: Vallparadis ParK (VP), Sant Cugat (SC), Fluvial del Besòs (BP), Ciutadella (CP) and Pegaso (PP).

Seed bank: Creation of a seed bank and database with high potential as new coagulants and antimicrobials

Database provided by the City Council

Extraction and purification of aqueous seed extracts.

Determination of antibacterial and coagulant activity

Creation of a seed location map with potential for water treatment

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Optimization of the use of plant-based coagulants from urban parks and gardens in Terrassa

🡪 Jar Test Process :

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Rapid Mixing

200 rpm

2 min

Slow Mixing

30 rpm

20 min

Settling

-

30 min

 Calibration Curve

To accurately correlate absorbance readings with turbidity concentrations in the jar test samples.

Current status of urban parks: Physicochemical parameters analysis

Physical and chemical parameters

a

b

c

d

Physicochemical analyses were performed to evaluate seasonal variations in water quality across urban parks in Catalonia. Elevated total nitrogen concentrations were detected in autumn and winter, likely due to increased runoff and reduced biological uptake under low temperatures. In contrast, total organic carbon (TOC) peaked in spring up to 30 mg/L in Besòs and Sant Cugat, linked to intensified vegetative activity and anthropogenic inputs. Ciutadella and Pegaso exhibited the highest electrical conductivity and total dissolved solids (TDS), suggesting mineral accumulation and possible impacts from urban maintenance and reduced water exchange, Fig 5 .

Fig 5. Evaluation of physicochemical water parameters during different climatic seasons: autumn 2024 (a); winter 2025 (b); spring 2025 (c) and all seasons (d).

Ciudadella Park had the highest concentration of fecal coliforms and E. coli in sediment compared to water.

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Vallparadís Park had the highest concentration of fecal coliforms and E. coli in water compared to sediment.

Isolation and characterization AMR bacteria from urban parks

Current status of urban parks: Microbiological analysis

Total Coliform and E. coli Concentration

Autumn 2024 Sampling Campaign

New potential coagulants and antimicrobials active compounds

We found a total of 165, 168 and 96 isolates resistant to TZ, SXT and TC, respectively. In addition, a total of 65 lactose fermenting organisms from the isolates obtained in the R2A and TSA plates supplemented with CO using the McConckey agar. The data show two interesting findings: The first is higher number AMR bacteria against all the screened antibiotics that were obtained from the PC samples. The PC AMR isolated bacteria accounted for around a 48, 34 and 59% of the total abundance of AMR bacteria against TZ, SXT and TC, respectively. The other is that the number of TC resistant bacteria is much lower than to other antibiotics, especially if we focus on PP, PV and PSC, Fig 6.

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Fig 6. 1a, 1b, 2a, 2b, 3a, 3b, 4a and 4b. Figures 1a–3a show the total number of AMR bacteria resistant to a particular antibiotic, broken down by urban park, sample type, and culture medium. Figures 1B–3B show the percentage of isolates obtained from each park. Figures 4a and 4b show the same information but only for re-inoculations onto MacConkey agar plates.

1a

1b

2a

2b

3a

3b

4a

4b

44 ornamental plant species provided by the Terrassa City Council and collected from Sant Jordi Park, 14 species demonstrated promising coagulation-flocculation potential and antimicrobial activity.

 

Species

 

Parts Used

 

Extraction Method

 

Dosage 10% (v/v)

Initial Turbidity (NTU)

Final Turbidity (NTU)

Removal percentage

(%)

 

 

 

NCC

 

 

 

Seeds

 

 

Salt Solution

1000

1000

16,8

98,32

500

36,8

92,64

100

100,5

0,00

500

500

37,1

92,59

100

500

54,3

89,15

100

43,8

56,22

 

 

 

NC1

 

 

 

Seeds

 

 

Salt Solution

1000

1000

296,0

70,40

500

175,3

64,94

100

61,5

38,54

500

500

328,6

34,29

100

500

243,9

51,22

100

34,4

65,61

 

 

 

NC2

 

 

 

Seeds

 

 

Salt Solution

1000

1000

365,1

63,49

500

172,8

65,44

100

49,0

50,97

500

500

359,5

28,10

100

500

250,5

49,90

100

35,7

64,30

 

 

 

NC3

 

 

 

Seeds

 

 

Salt Solution

1000

1000

338,2

66,18

500

171,3

65,74

100

62,3

37,73

500

500

267,0

46,60

100

500

340,0

31,99

100

40,1

59,90

Table 3, shows the natural extracts selected with the highest turbidity removal efficiencies in synthetic water containing kaolin. Among them, one species exhibiting both high turbidity removal and strong antibacterial properties was further investigated to optimize its inhibitory effects using various solvents, including hexane and ethanol, as shown in Fig 7. Ethanol extracts showed superior performance, attributed to the presence of bioactives such as tannins, flavonoids, saponins, alkaloids, and phenolic acids. These compounds enhance turbidity removal by promoting particle destabilization and floc formation, while also exhibiting significant antibacterial activity, particularly against E. coli and S. aerius as is shown in Fig 8.

Fig 8. Minimum Inhibitory Concentration (MIC). 1a, 1b, 2a, 2b, 3a and 3b. Figures 1a and 1b show the bacterial inhibition by NCC. Figures 2a and 2b show the inhibition by NC1 and NC1H. Figures 3a and 3b show the bacterial inhibition by NC1 and NC1E.

Fig 7. Turbidity removal percentage using CN1 with hexane and ethano solvents

1a

1b

2a

2b

3a

3b

Table 1. Turbidity removal efficiency using plant-based coagulants

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  • Seasonal changes significantly influenced water quality, with high nitrogen in colder months and elevated TOC in spring due to vegetation and urban activity. EC and TDS peaks suggest anthropogenic impact and poor water circulation.

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  • Antimicrobial-resistant bacteria were prevalent, especially in Ciutadella Park, with the highest resistance observed against ceftazidime, tetracycline, colistin and sulfamethoxazole.

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  • Ethanol plant extracts showed high turbidity removal and strong antibacterial activity, supporting their potential as sustainable, plant-based coagulants for urban water treatment.
  • Deikman, J., Petracek, M., & Heard, J. E. (2012). Drought tolerance through biotechnology: improving translation from the laboratory to farmers’ fields. Current Opinion in Biotechnology, 23(2), 243–250. doi:10.1016/j.copbio.2011.11.003
  • Liguori, K., Keenum, I., Davis, B. C., Calarco, J., Milligan, E., Harwood, V. J., & Pruden, A. (2022). Antimicrobial Resistance Monitoring of Water Environments: A Framework for Standardized Methods and Quality Control. Environmental Science & Technology, 56(13), 9149-9160. https://doi.org/10.1021/acs.est.1c08918
  • Nimesha, S., Hewawasam, C., Jayasanka, D. J., Murakami, Y., Araki, N., & Maharjan, N. (2022). Effectiveness of natural coagulants in water and wastewater treatment. Global Journal of Environmental Science and Management, 8(1), 101-116. https://doi.org/10.22034/GJESM.2022.01.08

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