Sustainable Water Use in a Fruit Processing Plant: Evaluation of Microbiological and Physicochemical Properties of Wash Water after Application of a Modular Water Recovery System

: The reuse of wash water in the agri-food industry is in line with sustainability goals through the reduction of the water footprint. Depending on the production process and raw material type, wash waters may exhibit severe biological and physicochemical contamination. The use of traditional methods of chlorine disinfection of water may be linked to the formation of hazardous by-products. The recycling of contaminated water should be supported by the evaluation of physicochemical and microbiological parameters before and after application of a treatment to validate the process. This study aimed to assess physicochemical and microbiological properties of rinse water from a post-harvest processing plant before and after applying an innovative modular water treatment system. The test material was washing water after apple rinsing obtained from a post-harvest processing plant (Northern Poland). The water recovery system included a wash water tank, a sand pre-ﬁlter, an ultraﬁltration system, and an ozonation tank. No microorganisms were found in the treated water. The physicochemical properties of the water were also improved: pH, conductivity, turbidity, ammonium ion, bromide, and nitrate content. The results indicate that rinse water from the fruit industry may be effectively puriﬁed using the tested puriﬁcation system and reused in production processes.


Introduction
Anthropogenic climate change presents a substantial risk to aquatic ecosystems, which are crucial reservoirs of water for human use.At present, over 25% of the global population faces the looming challenge of inadequate drinking water supply, leading to adverse impacts on human health, animal well-being, and agricultural productivity [1,2].The food industry stands out as one of the most water-intensive sectors in the economy.Specifically, the fruit and vegetable sector requires significant water volumes for the pre-treatment of raw materials, with agricultural activities alone accounting for 70% of the world's freshwater resources consumption [3][4][5].Water in fruit and vegetable processing plants is mostly used for pre-cleaning raw material to remove soil and impurities and rinsing the peeled raw material.According to estimates, processing 1 kg of fruit and vegetables requires the consumption of 5 L of water in post-harvest processing plants.Consequently, this implies the generation of wastewater with varying physicochemical and biological properties based on the processed raw material.It is worth noting that not all plants engage in the recycling of wash water.This lack of recycling contributes to the inefficient use of resources and incurs additional costs, potentially adversely affecting the economic viability and competitiveness of businesses [6,7].Therefore, it is necessary to increase investments, funds, and efforts that contribute to the reduction of water consumption through the implementation of sustainable development principles in agri-food production.
Applying the concept of water footprint (WF) to evaluate freshwater consumption and contamination enables effective modeling perspectives in water resource management [3,8,9].WF, defined as a virtual indicator of the total amount of water used to produce goods and services consumed per person (or group of persons), is gaining popularity and is becoming the focus of new studies [9].WF reduction is one of the goals of sustainable development, and the implementation of circular economy (CE) principles is an effective tool for achieving it [10].At its core, the concept of circular economy (CE) entails the restorative use of resources, aiming to decrease energy consumption and minimize waste production [11].Maximizing resource utilization, with a concentrated effort on minimizing waste generation, necessitates an integrated approach across all facets of production.Simultaneously, sustainable development must not only meet economic objectives but also extend to environmental and social dimensions, ensuring benefits for both present and future generations [12].
One of the challenges in treating wash water in agri-food plants is the presence of a substantial amount of particulate and organic matter in the post-process water from the agri-food industry.This significantly affects the purification processes [7].Conversely, rinse water may be an environment for periodic residence and growth of a significant number of microorganisms, making its treatment costly [13].Microbiological monitoring of rinse water is preventive, addressing the potential for cross-contamination between batches of raw material.Pathogen contamination, particularly in minimally processed products, can lead to outbreaks that pose a serious threat to public health.Furthermore, rinse water may contribute to the propagation of saprotrophic organisms, negatively impacting the final product's quality [14,15].The utilization of classical chlorine disinfection methods, especially in water with a substantial organic carbon load, may be linked to the formation of hazardous and carcinogenic by-products known as trihalomethanes.Employing chlorinefree water treatment methods helps mitigate the adverse effects associated with chlorine use [16].One potential solution involves the implementation of a modular water treatment system, incorporating flocculation, pre-filtration, ultrafiltration using filter tubes, and ozonation.This comprehensive approach ensures the treatment of post-process water for both physicochemical and microbiological properties [17].
The study assesses the effectiveness of purification of wash water from the agri-food industry by the water recovery system that complies with the latest standards and recommendations related to circular economy and sustainable development.To evaluate the effectiveness of purification by a modular water treatment system, selected physicochemical and microbiological properties of wash water collected from a fruit and vegetable processing plant before and after treatment were analyzed.Analysis of system performance through the investigation of microbiological and physicochemical properties of water can contribute to the adoption and promotion of effective sustainability and closed-loop economy solutions in fruit and vegetable processing plants.This, in turn, lead to a reduction in water footprint and bring about environmental, social, and economic benefits.

Description of the Collection Site and Water Samples
The study material consisted of apple rinsing water, sourced from an agri-food processing plant situated in the Kuyavian-Pomeranian voivodeship (Northern Poland).The plant adheres to Integrated Fruit Production principles in the cultivation of raw materials.Equipped with controlled atmosphere cold stores, the facility conducts ongoing monitoring of temperature, relative humidity, oxygen, carbon dioxide, and ethylene levels during storage.Employing the SmartFresh quality system, the plant extends the shelf life of food products without altering the consumer quality of the fruit.The fruit-growing area spans approximately 200 hectares, with an annual production reaching up to 10,000 metric tons.Apple varieties cultivated include Piros, Delicates, Lobo, Cortland, Elstar, Shampion, Boskop, Gloster, Idared, Ruby, Jonagold, Jonagored, Jonica, and Decosta.Samples were collected from three water channels: the sorting channel (sample ID: S), the collecting channel (sample ID: C), and the packing channel (sample ID: P) in July 2022.The channels constituted a connected water system; consequently, samples for physicochemical analysis were pulled and tested collectively.The raw material underwent washing with tap water devoid of any disinfectant additives.The research was conducted three times to ensure the reliability of the results.For the microbiological analysis, the detected colony values were averaged and presented in the form of a table.

Microbiological Analysis
Samples for microbiological tests were collected according to the Polish Standard (PN- EN ISO 19458:2007).After collection, the test materials were transported to the laboratory of the Department of Microbiology and Food Technology, Bydgoszcz University of Science and Technology (Bydgoszcz, Poland).Subsequently, the water was subjected to microbiological analyses via membrane filtration using a 3-station filter unit (Sartorius, Göttingen, Germany).The following groups of microorganisms were isolated on appropriate culture media: Escherichia coli (and Enterobacteriaceae family), (medium: Agar Endo, Merck), Staphylococcus aureus (and Staphylococcus spp.), (Chapman-agar, Merck), Pseudomonas aeruginosa (Pseudomonas Selective agar, Merck), Legionella sp.(Legionella CYE-Agar, Merck), Enterococcus spp.(Kanamycin esculin azide agar, Merck), Salmonella spp.(SS agar, Merck), total microorganism number (Standard I Nutrient Agar, Merck).After the incubation period, the grown colonies typical for a particular group were counted to determine the cfu/100 mL.Subsequently, pure bacterial cultures were established, and species identification was performed using spectrometry with a MALDI Biotyper apparatus (Bruker Daltonik GmbH, Bremen, Germany) with CE and IVD certification (compliance with Directive 98/79/EC [18]).Identical microbiological tests were repeated for the water after treatment.

Physicochemical Analysis
The wash water for laboratory testing was collected in accordance with PN-ISO 5667-5: 2017-10 [19] guidelines.Polypropylene bottles were filled to overflowing.Then, the bottles were sealed.After collection, the water was labelled for subsequent identification.Physicochemical testing of the water was carried out under laboratory conditions using the following standards for the determination of water parameters: - The physical and chemical results were subjected to statistical analysis.One-way ANOVA was used to evaluate significant statistical differences.Comparison of means was performed using Tukey's method.Statistical calculations were performed in Microsoft Excel 2016.Significance was defined as p < 0.05.

Water Recovery System
The study utilized an innovative closed-loop wash water treatment system.A detailed description of this system was previously incorporated in our own investigation on the properties of swimming pool water [17].Approximately 80% of the water quantity is recovered within this system, which is significant for advancing sustainable and resource-efficient water management.The system encompasses the processes of flocculation, prefiltration, ultrafiltration, and ozonation (Figure 1).The flocculation stage occurs within the wash water tank.Following this, the water is drawn in by a circulation pump and transferred to a pre-filter filled with sand.This pre-filter effectively eliminates mechanical contaminants, suspended solids, and colloidal particles.The sand filter is subsequently linked to the ultrafiltration system.The ultrafiltration system was constructed using 60 hemodialysis tubes.Following their medical application, the filters undergo a cleaning, sterilization, and assembly process to purify water under pressure.Each filter tube comprises thousands of fibers, with each fiber operating as a nephron, effectively eliminating up to 99.9% of bacteria, viruses, organic materials, matting agents, suspended particles, and colloids from the water.The final stage of the process involves water disinfection with ozone, with the ozonator demonstrating an efficiency of up to 5 g × h −1 .
ANOVA was used to evaluate significant statistical differences.Comparison of means was performed using Tukey's method.Statistical calculations were performed in Microsoft Excel 2016.Significance was defined as p < 0.05.

Water Recovery System
The study utilized an innovative closed-loop wash water treatment system.A detailed description of this system was previously incorporated in our own investigation on the properties of swimming pool water [17].Approximately 80% of the water quantity is recovered within this system, which is significant for advancing sustainable and resourceefficient water management.The system encompasses the processes of flocculation, prefiltration, ultrafiltration, and ozonation (Figure 1).The flocculation stage occurs within the wash water tank.Following this, the water is drawn in by a circulation pump and transferred to a pre-filter filled with sand.This pre-filter effectively eliminates mechanical contaminants, suspended solids, and colloidal particles.The sand filter is subsequently linked to the ultrafiltration system.The ultrafiltration system was constructed using 60 hemodialysis tubes.Following their medical application, the filters undergo a cleaning, sterilization, and assembly process to purify water under pressure.Each filter tube comprises thousands of fibers, with each fiber operating as a nephron, effectively eliminating up to 99.9% of bacteria, viruses, organic materials, matting agents, suspended particles, and colloids from the water.The final stage of the process involves water disinfection with ozone, with the ozonator demonstrating an efficiency of up to 5 g × h⁻ 1 .

Results of Microbiological Tests
The results of the microbiological analyses are presented in Table 1.The highest microbiological contamination was observed in water samples collected from the packing channel at a concentration of 5.1 × 10 4 cfu/1 mL.E. coli, an indicator bacterium for water quality, was detected in the tested water at levels of 1.3 × 10 1 (channel S) and 1.2 × 10 2 cfu/100 mL (channel C).Representatives of the Enterobacteriaceae family were identified in samples from water channels S and C. Additionally, potentially pathogenic bacteria of the

Results of Microbiological Tests
The results of the microbiological analyses are presented in Table 1.The highest microbiological contamination was observed in water samples collected from the packing channel at a concentration of 5.1 × 10 4 cfu/1 mL.E. coli, an indicator bacterium for water quality, was detected in the tested water at levels of 1.3 × 10 1 (channel S) and 1.2 × 10 2 cfu/100 mL (channel C).Representatives of the Enterobacteriaceae family were identified in samples from water channels S and C. Additionally, potentially pathogenic bacteria of the genus Enterococcus were present in all channels at concentrations of 2.24 × 10 2 , 2.2 × 10 2 , and 2.7 × 10 2 cfu/100 mL, respectively (Table 1).
The analyzed water samples did not exhibit the presence of S. aureus; nevertheless, representatives of this genus were identified in all investigated water channels (S, C, and P), with corresponding abundances of 1.5 × 10 1 , 2.1 × 10 2 , and 1.5 × 10 1 cfu/100 mL.Comparable tests performed on the water after the treatment process did not confirm the presence of the tested bacterial groups.Based on a mass spectrometry (MALDI-TOF MS) identification, it was found that opportunistic bacterial species were present among the detected bacteria in the raw water: Myroides odoratimimus, Serratia fonticola, Raoultella ornithinolytica, Bacillus pumilus and Staphylococcus xylosus.Among the determined species of enterococci, Enterococcus durans was the predominant species (Table 2).

Results of Physicochemical Tests
Based on the results, all water parameters were improved as a result of the treatment process.Beneficial changes occurred both in general parameters, such as pH or turbidity, and in specific differences relating to ionic and chemical content.In addition, all tested parameters fulfilled the standards for drinking water after treatment.
The decrease in the pH level of the test water is an outcome of the reduced concentration of alkaline ions during the treatment process (Figure 2).The pH level in the purified water decreased on average from pH 7.71 to 7.32.The water conductivity was also reduced, attributed to a decrease in the overall number of dissociated substances in the water (Figure 3).Based on the obtained results, it can be affirmed that the conductivity of the purified water decreased by 25.6%.1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
Water treatment had no effect on water hardness.The difference between the wash water and the treated water falls within the margin of measurement error.No statistically significant difference was observed before and after the implementation of the modular water treatment system (Figure 4).Changes in pH level before and after the treatment process (* for definitions of A and B, see Table 1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
The water conductivity was also reduced, attributed to a decrease in the overall number of dissociated substances in the water (Figure 3).Based on the obtained results, it can be affirmed that the conductivity of the purified water decreased by 25.6%.The water conductivity was also reduced, attributed to a decrease in the overall num ber of dissociated substances in the water (Figure 3).Based on the obtained results, it can be affirmed that the conductivity of the purified water decreased by 25.6%.1; LSD-least significant difference; significance of differences tested with Tukey's tes at p ≤ 0.05).
Water treatment had no effect on water hardness.The difference between the wash water and the treated water falls within the margin of measurement error.No statisticall significant difference was observed before and after the implementation of the modula water treatment system (Figure 4).Changes in conductivity before and after the treatment process (* for definitions of A and B, see Table 1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
Water treatment had no effect on water hardness.The difference between the wash water and the treated water falls within the margin of measurement error.No statistically significant difference was observed before and after the implementation of the modular water treatment system (Figure 4).1; LSD-least significant difference; n.s.-not significant; significance of differences tested with Tukey's test at p ≤ 0.05).
The raw rinse water exceeded the turbidity level by more than one NTU; carrying out the treatment process resulted in an average value of 0.79 NTU (Figure 5).Changes in turbidity level before and after the treatment process (* for definitions of A and B, see Table 1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
The results show an average decrease in ammonium ion content of 65.86% (Figure 6).In addition, similar changes were observed for nitrate and bromide concentrations, which decreased by 63.04% and 65.27%, respectively (Figures 7 and 8).The raw rinse water exceeded the turbidity level by more than one NTU; carrying out the treatment process resulted in an average value of 0.79 NTU (Figure 5).The raw rinse water exceeded the turbidity level by more than one NTU; carrying out the treatment process resulted in an average value of 0.79 NTU (Figure 5).Changes in turbidity level before and after the treatment process (* for definitions of A and B, see Table 1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
The results show an average decrease in ammonium ion content of 65.86% (Figure 6).In addition, similar changes were observed for nitrate and bromide concentrations, which decreased by 63.04% and 65.27%, respectively (Figures 7 and 8). .Changes in turbidity level before and after the treatment process (* for definitions of A and B, see Table 1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
The results show an average decrease in ammonium ion content of 65.86% (Figure 6).In addition, similar changes were observed for nitrate and bromide concentrations, which decreased by 63.04% and 65.27%, respectively (Figures 7 and 8).
The most substantial average changes, exceeding 60%, were observed (in order of decreasing magnitude) for bromide and ammonium ion concentrations followed by turbidity and nitrate levels, concerning the physicochemical properties of the water (Figure 9).The most substantial average changes, exceeding 60%, were observed (in order of decreasing magnitude) for bromide and ammonium ion concentrations followed by turbidity and nitrate levels, concerning the physicochemical properties of the water (Figure 9).

Discussion
This study represents the first use of the studied modular wash water recovery system in the agri-food industry, focusing in particular on post-harvest processing plants.Previous studies carried out by our team have mainly focused on pool water [17,27].
The conducted tests revealed the absence of indicator bacteria commonly employed in evaluating the microbiological purity of water, including S. aureus, P. aeruginosa, Legionella spp., and Salmonella spp.However, E. coli was detected in the samples.It is worth noting that the tested water originated from apple washing processes; the presence as well as the quantity of E. coli and coliforms may vary depending on the raw material undergoing processing [28].The identification of E. coli in the water samples confirms its status as a common indicator of water quality, signifying the potential presence of fecal contamination and serving as a significant epidemiological factor.Moreover, from an industrial perspective, E. coli bacteria could serve as a source of cross-contamination for the processed raw material [13].The presence of other members of the Enterobacteriaceae family in water poses a significant threat.It is important to highlight that a prevalent resistance mechanism within the Enterobacteriaceae family involves the hydrolysis of clinically important β-lactam antibiotics, including third generation cephalosporins (such as cefotaxime, ceftazidime, and others) [29].The study revealed the absence of Salmonella bacteria, which are commonly isolated from production environments in the food industry [4].The identification of enterococci in water is subject to regulation based on the standards specific to each country [30].Our own studies confirmed the presence of Enterococcus spp.; however, species identification using mass spectrometry indicated the presence of E. durans, which is not a typical representative of this genus such as E. faecalis and E. faecium.Nonetheless, this microorganism has the potential to cause opportunistic infections in humans, making its presence in rinse water undesirable [31,32].Myroides odoratimimus is a bacterium commonly associated with both soil environments and contaminated water

Discussion
This study represents the first use of the studied modular wash water recovery system in the agri-food industry, focusing in particular on post-harvest processing plants.Previous studies carried out by our team have mainly focused on pool water [17,27].
The conducted tests revealed the absence of indicator bacteria commonly employed in evaluating the microbiological purity of water, including S. aureus, P. aeruginosa, Legionella spp., and Salmonella spp.However, E. coli was detected in the samples.It is worth noting that the tested water originated from apple washing processes; the presence as well as the quantity of E. coli and coliforms may vary depending on the raw material undergoing processing [28].The identification of E. coli in the water samples confirms its status as a common indicator of water quality, signifying the potential presence of fecal contamination and serving as a significant epidemiological factor.Moreover, from an industrial perspective, E. coli bacteria could serve as a source of cross-contamination for the processed raw material [13].The presence of other members of the Enterobacteriaceae family in water poses a significant threat.It is important to highlight that a prevalent resistance mechanism within the Enterobacteriaceae family involves the hydrolysis of clinically important β-lactam antibiotics, including third generation cephalosporins (such as cefotaxime, ceftazidime, and others) [29].The study revealed the absence of Salmonella bacteria, which are commonly isolated from production environments in the food industry [4].The identification of enterococci in water is subject to regulation based on the standards specific to each country [30].Our own studies confirmed the presence of Enterococcus spp.; however, species identification using mass spectrometry indicated the presence of E. durans, which is not a typical representative of this genus such as E. faecalis and E. faecium.Nonetheless, this microorganism has the potential to cause opportunistic infections in humans, making its presence in rinse water undesirable [31,32].Myroides odoratimimus is a bacterium commonly associated with both soil environments and contaminated water [33].While M. odoratimimus rarely causes opportunistic infections in humans, its increasing multiresistance in recent years has garnered attention, posing challenges for effective treatment [34].Also, water-associated Serratia fonticola can be an opportunistic etiological agent of biliary tract infections, urinary tract infections and endocarditis [35][36][37].Raoultella ornithinolytica, widely distributed like the microorganisms mentioned earlier, has the potential to pose a threat to individuals with compromised immune systems [38].Individual strains of the soil-associated species Bacillus pumilus can function both as plant growthpromoting microorganisms and as plant pathogens.Additionally, they may rarely serve as the etiological agent of human diseases [39].The variety of wash water depends on the process and the type of raw material [4].All isolated microorganisms are able to produce a biofilm and may exhibit multiresistance [32,34,36,38].At present, to the best of our knowledge, there are few studies on bacteria residing in rinse water in the agri-food industry.
Our study demonstrates an alternative to traditional water disinfection methods.Chlorine-based compounds are usually added to the water to prevent cross-contamination of the product [40]; however, in the case of this study, disinfectants were not added.Additionally, as noted by Gao et al., the incorporation of antimicrobial agents enables effective control of cross-contamination [41].Also, the use of peracetic acid makes it possible to effectively reduce the concentration of bacteria, including Listeria monocytogenes [42].Despite the strong microbial load of the test water (total number of microorganisms, 36 ± 2 • C after 48 h), the use of a modular water treatment system allowed for the complete elimination of cfu/1 mL.These results correspond with previous in-house studies related to the treatment of swimming pool rinse water, where a reduction in microorganisms of more than 99% was found [17].It is worth noting, however, that due to environmental stress, many bacterial species can enter a viable but nonculturable (VBNC) phase, rendering them unidentifiable using classical culture methods [43].On the other hand, each module of the water treatment system carries out processes with properties that reduce the number of microorganisms.The use of coagulation, flocculation, and sedimentation is usually one of the first stages of water treatment, which contributes to mechanically 'trapping' some of the bacteria in the solid fraction [44].As noted by Xiangli et al. the implementation of coagulation prior to the use of full-scale ultrafiltration is an effective method in the production of drinking water [45].The subsequent module, sand filtration, similarly contributes to diminishing the number of microorganisms in the treated water.Investigations into the implementation of slow-flow sand filtration reveal that it selectively reduces specific groups of microorganisms in the treated water [46].Ultrafiltration of water is a widespread method of water treatment.A study by Hembach et al. reported a decrease of an average of 5 log units in the number of both facultative bacteria and antibiotic resistance genes in the water tested, which originated from a wastewater treatment plant [47].An in-vitro study by Mota et al., indicated that the usage of ultrafiltration membranes effectively removed fish pathogens, including viruses, which may find wider application in aquaculture [48].These results confirm the high effectiveness of the use of ultrafiltration membranes.The use of inactivating mechanisms for bacteria and viruses through the implementation of water ozonation finds application in many industries, medicine and drinking water production, demonstrating effectiveness against, among others, water quality indicator bacteria [49].The incorporation of an ozone station as the last biocidal agent therefore contributes to the effective validation of the system.
One of the significant factors influencing the primary contamination of the examined water is the amount of suspended and dissolved solid fractions originating from the washed raw material.As noted by Mundi et al., the implementation of mathematical models as predictive tools for pollution can be an effective method for managing the production process, particularly concerning suspended solids, total solids, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, total nitrogen, total phosphorus, ammonia, and electrical conductivity [7].In the case of our study, the tap water used for rinsing met the requirements for drinking water, as indicated by the normative levels of chemical parameters (e.g., ammonium ion, bromide level, pH level).The apple rinsing process noticeably influenced the introduction of a significant amount of solid fraction, contributing to water turbidity.As noted by Farrel et al., a high level of turbidity can lead to the aggregation of particles with bacteria, negatively impacting the effectiveness of disinfection processes [50].Despite the relatively low turbidity level in the apple rinse water, the application of the modular system resulted in an improvement in this parameter.Nevertheless, further tests are warranted to assess the system's performance under conditions of high particulate load in water.A study conducted by He et al. suggests that the emphasis in water treatment processes should be primarily on controlling the number of particles smaller than 5 µm to enhance water clarity [51].As highlighted by López-Gálvez (2019), the influence on the physicochemical quality of post-process rinse water is not solely determined by the type of fruits and vegetables being cleaned but can also vary based on the implemented washing system [28].The substantial variations in water properties can pose a challenge to developing an integrated approach to management and implementing sustainable production principles in fruit and vegetable processing plants [52].
In the context of the potential implementation of this system, it is crucial to ensure control over the entire process to counteract factors that could disrupt the effective water treatment process.As highlighted by Gombas et al., elements of the water treatment process that are variable and can be controlled include factors such as the rate of product delivery, water pH, water replenishment rate, product-to-water ratios, organic and mineral substance content, as well as the quantity of solid substances [53].Prior research has demonstrated that water treated through the use of a modular system can be safely employed for irrigation purposes.The findings affirm the effectiveness of the water treatment process and its ability to deliver water with high safety standards, which holds significant importance in the context of environmental preservation and sustainable water resource utilization [27].

Conclusions
This pilot study serves as a prelude to further research associated with the implementation of water recovery systems in fresh-cut processing plants.The utilization of a pilot modular rinse water treatment system contributed to the effective elimination of microorganisms, whose presence could negatively impact the production process as well as public health.This is particularly significant since species identification, using mass spectrometry, indicated the presence of potentially opportunistic pathogens in the rinse water before implementation of the treatment.
The results of the study also point to an improvement in the physicochemical parameters of the water, enabling its potential reintegration into production processes.Considering these aspects, the examined system can be employed as a tool to reduce the water footprint and implement closed-loop economy practices in fruit and vegetable processing facilities.The implementation of a modular water recovery system not only translates into environmental benefits but also yields economic advantages for the company due to reduced water consumption and wastewater generation.
The comprehensive use of coagulation, sand filtration, ultrafiltration, and ozonation mechanisms holds potential for broader applications in the industry, influencing effective and sustainable water resource management.However, attention should be given to the need for further research to analyze the efficiency of treating rinse water under various conditions (type of raw material, water contamination level, facility location, adopted processing model, type of fruit and vegetable processing line, etc.).

Figure 3 .
Figure 3.Changes in conductivity before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 2 .
Figure2.Changes in pH level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 3 .
Figure 3.Changes in conductivity before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's tes at p ≤ 0.05).

Figure 3 .
Figure 3.Changes in conductivity before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 4 .
Figure 4. Changes in water hardness before and after the treatment process (* for definitions of A and B, seeTable 1; LSD-least significant difference; n.s.-not significant; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 5 .
Figure5.Changes in turbidity level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 4 .
Figure 4. Changes in water hardness before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; n.s.-not significant; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 5 .
Figure5.Changes in turbidity level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 5
Figure5.Changes in turbidity level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 6 .
Figure 6.Changes in ammonium ion level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).

Figure 9 .
Figure 9. Percentage decrease in physicochemical water parameters after water treatment.

Figure 9 .
Figure 9. Percentage decrease in physicochemical water parameters after water treatment.

Table 1 .
The results of studies with the use of membrane filtration.
* Abbreviations: A-water sample before treatment, B-water sample after treatment, n.d.-bacteria not detected.

Table 1 ;
LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Changes in nitrate level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Changes in ammonium ion level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).
Figure 6.Changes in ammonium ion level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Figure 7.Changes in nitrate level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Figure 7. Changes in nitrate level before and after the treatment process (* for definitions of A and B, see

Table 1 ;
LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Changes in bromide level before and after the treatment process (* for definitions of A and B, see Table1; LSD-Least Significant Difference, significance of differences tested with Tukey's test at p ≤ 0.05).
Figure 6.Changes in ammonium ion level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Figure 7.Changes in nitrate level before and after the treatment process (* for definitions of A and B, see Table1; LSD-least significant difference; significance of differences tested with Tukey's test at p ≤ 0.05).Figure 8.Changes in bromide level before and after the treatment process (* for definitions of A and B, see Table1; LSD-Least Significant Difference, significance of differences tested with Tukey's test at p ≤ 0.05).Figure 8.