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Article

Performance of Integrated Biofilm-Phytoremediation Process in Reclaiming Water from Domestic Wastewater

by
Fairuz Afiqah Buslima
1,*,
Hassimi Abu Hasan
1,2,3,*,
Jahira Alias
1,
Jaga Sahsiny Jaganathan
1,
Junaidah Buhari
1,
Suriya Vathi Subramanian
1 and
Siti Rozaimah Sheikh Abdullah
1,3
1
Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
2
Research Centre for Sustainable Process Technology (CESPRO), Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
3
Water and Wastewater Treatment Technology Research Group, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
*
Authors to whom correspondence should be addressed.
Water 2025, 17(2), 163; https://doi.org/10.3390/w17020163
Submission received: 25 November 2024 / Revised: 1 January 2025 / Accepted: 7 January 2025 / Published: 9 January 2025
(This article belongs to the Section Wastewater Treatment and Reuse)

Abstract

:
The rapid development of the residential and industrial sectors produces a huge amount of treated domestic wastewater. The treated wastewater is discharged and could affect the environment in the long term. Improving the quality of treated domestic wastewater for water reclamation would benefit both sectors. This study aims to determine the efficiency of the biofilm-phytoremediation integration process in reclaiming domestic wastewater. A cuboid-shaped reactor was filled with 15 L of domestic wastewater, utilizing water hyacinth and a polyethylene carrier as supporting media for the process. The integrated reactor is tested in two phases: the initial adaptation of bacteria with domestic and synthetic wastewater (Phase I) and the integration process of biofilm-phytoremediation, based on the factors of NH3-N concentration and hydraulic retention time (HRT), for 24 to 48 h (Phase II). In Phase II, pollutant removal was observed at varying NH3-N concentrations: C1 (11–13 mg/L), C2 (9–11 mg/L), and C3 (3–5 mg/L). The study’s findings indicate a consistent performance in the first phase, with removal rates for COD and NH3-N ranging between 86.7–100.0% and 79.0–99.6%, respectively. The reactor effectively removed pollutants at varying concentrations of NH3-N, with average removal up to 100% (COD), 99% (NH3-N), and 80% (PO43−). This integrated reactor shows the finest treated water quality outcomes for non-potable water recovery, as well as offers an alternative to resolve water scarcity for use in various sectors.

1. Introduction

Domestic effluent is widely recognized as a significant contributor to river pollution, posing a direct threat to aquatic ecosystems and human health [1]. An increasing number of aquatic ecosystems are threatened by ammonia pollution, of which domestic effluent is a significant source. The presence of ammonia reduces the oxygen content in a water stream [2]. Additionally, an excessive amount of ammonia is harmful to aquatic life [3]. Consequently, it must be removed from domestic effluent before its release into receiving water.
Biological methods such as sand biofilters, membrane bioreactors, and microalgae are the most developed and researched technologies for removing and recovering ammonia [4]. Biological methods have garnered considerable attention owing to their environmentally friendly nature and economic pricing. In contrast to the substantial energy and chemical investment typically required for physical and chemical processes, biological technologies utilize micro-organisms to eliminate contaminants, thereby harmonizing objectives related to the environment and economy [5]. Microbial-based biological processes, such as moving bed biofilm reactors (MBBR), have become a popular method for addressing these issues and removing pollutants [6]. Supported microbial biofilm systems have emerged as appealing, environmentally friendly, and financially advantageous methods. This is because they can prevent further harm to the environment [7]. However, biofilm in reactors typically experiences extended start-up times due to the necessary formation of active biofilms on the carriers [8]. This is particularly challenging for biofilm systems because the start-up period can be significantly longer; it requires time to ensure the formation of a thick biofilm, and the thickness of the active biofilm affects the activity of the system [8]. Nevertheless, as biofilm continues to develop, it will inevitably progress to the aging stage and accumulate on the media carrier surface, hindering the interaction between micro-organisms and pollutants and diminishing the biofilm method’s purification potential [9].
On the other hand, phytoremediation strategies have been employed to address the issue of eutrophication in aquatic habitats caused by low-strength wastewater [10]. The reason for this could be attributed to its benefits, including cost-effectiveness, minimal energy use, simplicity in operation and maintenance, and utilization of natural processes [11,12]. The free-floating plant Eichhornia crassipes (water hyacinth) has garnered much attention due to its rapid growth in wastewater. The accumulated data indicate that E. crassipes plants have a significant impact on the removal of nutrients from wastewater [13]. Lu et al. [14] studied the performance of various aquatic plants in remediating polluted rural rivers. Their findings indicated that water hyacinth had the highest efficiency in removing total nitrogen (TN: 89.4%) and ammonium–nitrogen (NH4+-N: 99%). The study also reported that an increase in hydraulic retention time (HRT) improved pollutant removal. Nevertheless, notable disadvantages of water hyacinth are the lengthy HRT, the significant land area required, and slow treatment methods.
Various combinations of distinct remediation approaches, such as the synergistic interactions between plants and microbes, can enhance the remediation process of several matrices, including air, water, and soil [15]. Ren et al. [16] studied the integration of a two-stage biofilm reactor to treat dispersed domestic wastewater. The outcome showed that the highest removal of chemical oxygen demand (COD) and NH4+-N were 94.2% and 85.7%, respectively. The integrated biofilm process requires a smaller land area and employs many methods, including anaerobic digestion, aerobic digestion, adsorption, and filtering, to effectively treat wastewater. This process is often utilized in decentralized wastewater treatment systems [16]. Song et al. [17] studied the performance of membrane-attached biofilm to treat wastewater. The resulting removal of 90.3% of the nitrogen was achieved. Nevertheless, the issue of membrane fouling is a significant obstacle to the practical implementation of promising membrane bioreactor technology, which is used to treat organic wastes and wastewater [18].
There is a prevailing tendency to employ an integration approach that incorporates at least two distinct processes to reduce the land area required for waste treatment. Unlike a single unit MBBR or phytoremediation process, this study addresses a dual mechanism of biological treatment processes to achieve higher treatment efficiency. Integration of MBBR and water hyacinth is believed to optimize wastewater treatment efficiency. The effluent from this treatment could also, potentially, be used for water reclamation. It is imperative to harness non-traditional water sources in order to maintain a sustainable future water supply. Currently, there is a widely accepted opinion that domestic wastewater should be considered a developing freshwater resource rather than a form of waste [19]. Prior to, and following the incorporation of, these two processes, the efficiency of the developed systems is assessed.
Therefore, the study evaluates the performance of integrated reactors across different phases, including the initial adaptation and process of integrated reactors, as well as ammonia concentrations and HRT. The efficiency is determined by monitoring the variations in several metrics, including COD, ammonia–nitrogen (NH3-N), and phosphate (PO43−). This study also compares the performance of the integration of MBBR and water hyacinth, which is more efficient than a single biological treatment. The MBBR acts as an initial treatment for removing organics and nutrients under varying influent conditions, while water hyacinth serves as a polishing stage to remove any remaining pollutants. This study contributes to knowledge about the integrated water treatment system approach and its implementation in reusable water.

2. Materials and Methods

2.1. Collection of Domestic Wastewater

One hundred liters of domestic wastewater samples were collected in a clean sample container from the Sewage Treatment Plant (STP) at Kolej Keris Mas (KKM) in the University of Kebangsaan, Malaysia (UKM). This STP is equipped with a basic filtration system, including a grit chamber, aeration, retention tanks, a scum skimmer, and a sludge drying area. The samples used for this study comprised raw domestic wastewater that had passed through a grit chamber to remove larger particles and debris. The samples were collected bi-weekly and were characterized.

2.2. Integrated Biofilm-Phytoremediation

The process of integrated biofilm-phytoremediation started with bacterial reproduction until the number of bacteria in the biomass reached the required amount (more than 1500 mg/L) in the reactor. A species of Burkholderia laten (NS2) was prepared before being put in the integrated reactor. In this study, a two-stage acclimatization process was conducted using raw domestic wastewater followed by synthetic wastewater.

2.2.1. Setup of the Integrated Biofilm-Phytoremediation Reactor

The integrated reactor was developed in laboratory scale conditions, combining both fixed and moving biofilm processes in a rectangular tank made up of polyvinyl chloride (PVC) material and with dimensions of 51 cm length × 26 cm width × 30 cm height, as shown in Figure 1. The domestic wastewater samples were stored in a cold room at 4 °C prior to use. The domestic wastewater was changed daily, with HRT set at 48 h and a total working volume of 15 L. The air diffuser was used to supply oxygen to the bacteria in the MBBR, as well as to support aerobic respiration.
Hexafilter media was used as the biofilm carrier for the moving bed biofilm reactor (MBBR), which was made of polyethylene material and designed with a surface area of 1460 mm2, while the height and diameter were 12 mm and 25 mm, respectively. The rough surface of the Hexafilter media provided a surface for bacteria adhesion, and this led to an increased surface area for cell immobilization [20,21]. The filling fraction was 30% of the reactor’s total volume filled with Hexafilter media. In this study, four water hyacinth plants with an average weight of 0.8–1.0 kg were used. The roots of the water hyacinth act as natural biofilm carriers and microbes become attached, absorbing pollutants. The average leaf width is between 8 and 10 cm, and the average number of leaves is 9 to 12. The water hyacinth plants were obtained from Engineering Lake, Faculty of Engineering and Built Environment, UKM. The plants were washed before experimental use.

2.2.2. Performance of Integrated Biofilm-Phytoremediation Reactor

The performance of the integrated reactor was carried out in two phases: I—the acclimatization process, and II—the integration process of biofilm-phytoremediation based on the factors of NH3-N concentration. Before the integrated reactor’s actual operation began, the MBBR’s acclimatization process was crucial for stabilizing the wastewater treatment. The information for each phase is shown in Table 1. This acclimatization process aimed to allow the bacteria to adapt to real wastewater conditions and facilitate the removal of COD and NH3-N. Stage I of the acclimatization involved the usage of real raw domestic wastewater from day 0 to 24, with an HRT of 24 h. During exposure to real wastewater, the microbial community stabilized its growth to the wastewater conditions. The influent for COD and NH3-N ranged from 20–78 mg/L and 0.11–22.82 mg/L, respectively. Next, from day 31 to 114, the second stage of acclimatization was carried out by using synthetic wastewater to accelerate bacterial growth and further acclimatize the microbial community. The influent of synthetic wastewater fed into the reactor consisted of less than 200 mg/L COD and 10 mg/L NH3-N.
Table 2 outlines the study guide details of the operation of an integrated biofilm-phytoremediation reactor in Phase II, from day 166 to 442 of operations. In this setup, domestic wastewater was initially treated in MBBR (R1), where bacteria attached to Hexafilter media facilitated the breakdown of pollutants over 24 h. Subsequently, 12 L of treated water was transferred to a phytoremediation reactor containing water hyacinth (R2), whose roots provided an additional surface area for biofilm growth, further enhancing the removal of pollutants. After the next 24 h in R2, an effluent sample was taken, and the water was continuously replaced with new domestic wastewater. The influent concentration of NH3-N in Phase II varied, with values of 12.66 mg/L (C1), 9.95 mg/L (C2), and 4.05 mg/L (C3), while the influent COD range was 17–123 mg/L. Analysis of pH, suspended solids (SS), COD, NH3-N, and PO43− was determined daily. The analysis of mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) was determined twice a week.

2.3. Analytical Methods

The pH reading was measured using a pH meter (HQ4300, HACH, Berlin, Germany). The DO reading was measured using a portable DO meter (YSI 550A, Yellow Springs, OH, USA). The photometric method (Method 8006, 5–750 mg/L) was used for SS analysis. The Nessler Method (Method 8038, 0.02–2.50 mg/L) was used for NH3-N, and the PhosVer 3 (Ascorbic Acid) Method (Method 8048, 0.02–2.50 mg/L) was used for PO43−. The Reactor Digestion Method (Method 8000, low range: 3–150 mg/L) was used for COD digestion with a COD reactor (DRB 200, HACH, Berlin, Germany). The concentrations of SS, NH3-N, PO43−, and COD were analyzed using a laboratory spectrophotometer (DR3900, HACH, Berlin, Germany).

3. Results and Discussion

3.1. Characterization of Domestic Wastewater

The monthly average values obtained from raw domestic wastewater are presented in Table 3. The initial concentrations of the parameters (pH, SS, NH3-N, COD, PO43−, NO2-N, and NO3-N) were determined before being put into the integrated reactor. From Table 3, it can be seen that the concentrations of NH3-N and COD increased during Q3 and Q4 due to the higher load of organic matter such as human excrement or chemical compounds. The higher load of organic matter can often be linked to seasonal patterns or activities on campus; more people use college facilities during Q3 and Q4, which can lead to increased water consumption and organic waste production. Additionally, it was estimated that the characteristics of domestic wastewater reflect a combination of greywater and blackwater [22].

3.2. Phase I: Acclimatization of the Bacteria in an Integrated Reactor

During the acclimatization process, pH and SS were continuously monitored, with a focus on observing the removal efficiencies of COD and NH3-N. The Phase I summary of the acclimatization process for Stages I and II is presented in Table 4. The pH value of the influent and effluent was about 6 to 8 and 6 to 7 for Stages I and II, respectively. The pH stability reflects the successful adaptation of the bacterial consortium to synthetic wastewater. The effluent SS value is relatively stable between 10 and 50 mg/L in Stage I. During Stage II, there are some fluctuations in the effluent SS value, ranging from 1–60 mg/L. This fluctuation is due to microbial activity, as the micro-organisms gradually adjust themselves to the new environment. The bacteria adjust by forming stable biofilms on the Hexafilter media and their metabolic adjustment toward the process of organic loads in wastewater, which helps the bacteria in the biofilm to survive and increase their activity to degrade organic compounds.
The influent COD concentrations in Stages I and II were in the ranges of 0–78 and 21–200 mg/L, respectively. Figure 2a shows that COD removal during Stage I fluctuates in the range of 0–100%. The effluent COD concentration is not stable and fluctuates significantly due to the adaptation of bacteria to domestic wastewater. After the transition to Stage II, there were initial fluctuations between 50 and 100%, which were most likely due to different compositions of synthetic wastewater, where the microbes are in the earlier stages of adaptation to the new environment. However, during Stage II, the removal seemed more stable, with COD removal up to 100%. This stability showed that the bacteria adapted to the environment within the reactor. The findings also indicate that microbes can effectively adapt to varying levels of COD and acclimate well to different environmental conditions.
Apart from that, Figure 2b shows a significant difference in NH3-N removal values, with percentages varying from 0.0 to 95.6% in Stage I, as the bacteria was in the process of adapting to the domestic wastewater environment in the reactor. During Stage II, the removal value became more stable, maintaining a value between 68.7 and 99.6%, showing that the bacteria had fully adapted to the environment. The NH3-N concentration in the effluent of Stages I and II varied from 0.01 to 22.69 mg/L and from 0.02 to 1.72 mg/L, respectively. From these results, it was proved that the bacteria were able to remove ammonia at both high and low NH3-N and adapt to the different environments provided. The initially high COD concentrations during Stage II provided an abundant carbon source for heterotrophic bacteria, which is crucial for microbial growth and activities. The study indicates that high COD enhances the microbe’s ability to remove NH3-N compared to low COD.
The amount of MLSS and MLVSS attached to the Hexafilter media is shown in Figure 2c. Analysis of MLSS and MLVSS started during Stage II. In the integrated reactor, the initial concentration of MLSS on the media was 100 mg/L, and MLVSS showed 110 mg/L. The concentration of MLSS and MLVSS fluctuated during the early acclimatization process, greatly increasing in the reactor and remaining over 1000 mg/L after day 59. After day 91, MLSS increased up to 3170 mg/L. The highest concentration of MLSS was on the 98th day (3530 mg/L), while the MLVSS concentration was 3980 mg/L on the 87th day. The increase in MLSS and MLVSS concentrations was due to the growth of a biofilm layer of microbes on the surface of the Hexafilter media. Based on Jagaba et al. [23], as MLSS increases, the removal efficiency of COD increases, and this has been proved in this experiment. Thus, the micro-organisms will adapt during the acclimatization process before they are ready to be utilized as an operational integrated reactor.

3.3. Phase II: Performance of Integrated Biofilm-Phytoremediation Process at Different Ammonia Concentrations

After 24 h of the MBBR process (R1), the parameter was analyzed at five HRTs (0, 4, 6, 8, and 24 h) in reactor phytoremediation (R2) until the removal rate of selected parameters stabilized. The average removal of NH3-N, COD, and PO43− from domestic wastewater was observed during the operation of this integrated reactor.

3.3.1. Removal of Ammonia–Nitrogen

The NH3-N removal under the factor of initial NH3-N concentration in a range of 4–13 mg/L is illustrated in Figure 3 and summarized in Table 5. After the first treatment with MBBR, the NH3-N reduced efficiency by up to 81%, 94%, and 92% for C1, C2, and C3, respectively. Following the next treatment, via phytoremediation using water hyacinth (R2), the maximum removal of NH3-N was achieved at 89% for C1, 98% for C2, and 99% for C3. The final effluent showed low NH3-N concentration values at 1.43, 0.21, and 0.07 mg/L for C1, C2, and C3, respectively, which are in accordance with Malaysian Water Quality threshold limits. This finding shows that the final effluent for C1, C2, and C3 was categorized under the Water Quality Index (WQI) based on classes I, II, and IV and could be suitable for recreational and irrigation purposes.
Significant improvement was observed in R2 for all NH3-N levels, but the highest efficiency was achieved in C3 due to the lowest concentration of NH3-N influent. The final effluent concentrations showed a significant improvement as the influent NH3-N concentration decreased. This indicates that the process is highly effective in removing NH3-N from domestic wastewater through the synergistic integration between biofilms and water hyacinth. Therefore, the presence of denitrifying bacteria on biofilm (e.g., ammonia-oxidizing bacteria (AOB) and nitrate-oxidizing bacteria—NOB) plays an important role in removing nitrogen compounds in wastewater. In addition, the removal of NH3-N gradually decreases during phytoremediation as a result of the uptake of ammonia by water hyacinth as a nutrient source for growth. As reported by Ting et al. [2], water hyacinth has a high nutrient uptake capacity, and nutrients are absorbed by the roots, making the mass of nitrogen and phosphorus higher in the leaves.

3.3.2. Removal of Chemical Oxygen Demand

The COD influent and effluent concentrations for various initial concentrations in the range 17–123 mg/L are shown in Figure 4 and Table 5. The COD concentration decreased within 48 h of treatment using the integrated biofilm-phytoremediation process. It decreased from initial concentrations of 40 to 1 mg/L for C1, 17 to 0 mg/L for C2, and 123 to 1 mg/L for C3. The treatment of MBBR for output R1 achieved a COD removal of 72% for C1, 80% for C2, and 66% for C3. Subsequently, followed by the phytoremediation treatment (R2), the maximum COD removal was 100% for C2 and C3 and 97% for C1. The relatively high COD removal in this treatment was due to the effectiveness of the biofilm and macrophytes process, which might be due to the combination of microbial degradation between the two processes that trap the organic compounds, even under varying influent loads [24,25]. The Hexafilter media maximizes biofilm formation and microbial activity, providing a conducive environment for bacteria to grow [21]. The bacteria degraded the organic matter in wastewater, which led to a decrease in COD. In this study, there were remarkably low COD levels of output R2 because the macrophytes effectively reduce the COD contents as the microbes present in the roots of plants. The microbes had the ability to use the oxygen released through photosynthesis to enhance the aerobic process and increase their efficiency in degrading organic pollutants [26]. The roots of plants not only support microbial activity but also directly remove organic pollutants. The process demonstrates its capability across varying influent loads, achieving COD effluent of 0–1 mg/L at all levels. A study by Zulkifli et al. [21] found a maximum COD removal of 95.9% using MBBR in domestic wastewater treatment, whereas this study showed COD removal up to 100% for C2 and C3. This indicates that an integrated biofilm-phytoremediation technology is more effective in reducing COD in domestic wastewater.

3.3.3. Removal of Phosphate

Figure 5 shows the average PO43− removal under concentrations of C1, C2, and C3 in the integrated biofilm-phytoremediation reactor. The average removal efficiency of PO43− in Phase II is 60–80% (Table 5). For C1, the initial PO43− concentration was 3.28 mg/L. The output R1 in MBBR recorded a percentage of PO43− removal of 19% (2.65 mg/L), whereas the output R2 recorded a percentage of PO43− removal of 64% (1.18 mg/L). The PO43− removal rate increased on day 195. For C2, output R1 recorded a PO43− removal of 57%, which is higher than output R1 in C1. The performance of output R2 remained good, with 80% of PO43− removed. The performance of C3 was similar to that of C1. Output R2 outperformed output R1, with a PO43− removal rate of 66%, whereas the removal rate of output R1 was only 22%. The PO43− removal fluctuated in the three concentrations due to the wilting of some plants in output R1 and R2. However, the removal was seen to increase slightly once the plants were replaced with a new batch. This indicates that water hyacinth plays a significant role in PO43− adsorption. The results obtained agree with the previous study conducted by Kumar and Deswal [27] and Zainuddin et al. [28], where water hyacinth recorded total phosphate removal up to 80% and 27.4%, respectively. Water hyacinths are able to provide long and fibrous roots, which promote better microbial activity around them (rhizosphere) and help transform pollutants [29]. Rhizosphere microbes have the potential for nutrient uptake to promote plant growth and the decomposition of nitrogen, phosphorus, and organic pollutants around the rhizosphere zone [28]. By combining the microbial community in the biological treatment of MBBR with the plant-based nutrient uptake capabilities of phytoremediation, enhanced PO43− removal can be achieved.

3.3.4. Comparison with Previous Studies

A comparison of our results with previous studies is summarized in Table 6. Based on the results, it can be concluded that the treated water is suitable for reuse in non-potable applications. The comparative analysis highlights the efficiency of the integrated process, demonstrating significant improvements in COD and nutrient removals. Most of the studies reported that the phyto-biofilm process achieved COD and NH3-N removals in the range 67–90%, while, for PO43−, the range was between 57% and 80%. Comparing the performance of the integrated process, as well as the single unit of MBBR and the phytoremediation process, this research demonstrates higher removal efficiency.
In this study, NH3-N removal reached up to 99%, which is comparable to the study by Nurdin et al. [30]. The results align with Chen et al. [31], confirming that high COD levels promote the removal of both NH3-N and PO43− by supporting heterotrophic microbial growth. Studies conducted by Auchterlonie et al. [35] also support the findings of this study. However, it only highlighted the performance of water hyacinth in a single processing unit, removing up to 93.8% PO43−. Studies conducted by Utami [33] also corroborate this study as 80% of PO43− was removed, with influent concentrations varying from 2.21 to 3.12 mg/L. The presence of biofilm on the roots of water hyacinth contributed to the removal of the PO43− at higher initial loads, indicating significant interaction between biofilm and water hyacinth. However, the initial concentration of COD in this study was lower compared to previous studies but the highest removal was able to reach 100% due to the combination of water hyacinth and bacteria attached to the biocarriers in the MBBR process. Hence, the significance of this study lies in its ability to address the challenges of reclaiming domestic wastewater using the sustainable approach of an integrated biofilm-phytoremediation process.

4. Conclusions

In this study, the integrated biofilm-phytoremediation process, which combines a MBBR and phytoremediation process, is highly effective in removing pollutants from domestic wastewater. The factors that affect the whole process efficiency are based on the absorption capacity of water hyacinth roots and the presence of microbes attached to the surface of the Hexafilter media. The integrated reactor consistently removes COD and NH3-N during acclimatization Phase I. As for the performance of Phase II, throughout the concentration of C1 to C3, this study proves that it removed up to 100% of COD, 99% of NH3-N, and 80% of PO43−. The process demonstrates the effectiveness of combining biofilm with macrophyte-based processes. The integrated biofilm-phytoremediation reactor offers a green technology alternative and makes it a viable solution for enhancing treated water quality for non-potable uses. It is recommended that future studies are conducted to optimize the condition factors of integrated reactors by treatment periods and the influent conditions and to stabilise performance under varying loads, particularly for COD and PO43−. To achieve optimal removal and improve the quality of wastewater, the type and amount of microbes bio-augmented in the treatment process need to be adjusted according to specific conditions. Other than that, future research could further explore the long-term impacts and scalability of this integrated system in various environmental contexts.

Author Contributions

Conceptualization, F.A.B. and H.A.H.; Methodology, F.A.B. and H.A.H. Validation, H.A.H.; Formal analysis, F.A.B.; Investigation, F.A.B.; Resources, H.A.H.; Writing—original draft, F.A.B., J.A., J.S.J., J.B. and S.V.S.; Writing—review & editing, H.A.H.; Supervision, H.A.H. and S.R.S.A.; Funding acquisition, H.A.H. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Ministry of Higher Education, Malaysia with the Transdisciplinary Research Grant Scheme (Grant no.: TRGS/1/2022/UKM/02/3/1).

Data Availability Statement

Data are contained within the article.

Acknowledgments

The authors would like to acknowledge the Ministry of Higher Education, Malaysia, for funding this research programme through the Transdisciplinary Research Grant Scheme (TRGS) through the grant titled “Resilience and Security of Water through Sustainable Localised Domestic Wastewater Reclamation for Landscaping and Toilet Use” (Grant no.: TRGS/1/2022/UKM/02/3), specifically “Project No. 1: Immobilised Microalgae-Photocatalytic Membrane Technology for the Elimination of Emerging Contaminants and Viruses for High Quality Reclaimed Domestic Wastewater” (Grant no.: TRGS/1/2022/UKM/02/3/1).

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Bai, F.; Liu, S.; Gu, X.; Wang, F. Highly efficient low-temperature biodegradation of nitrogenous pollutions in domestic wastewater via immobilized-microbial bioaugmentation coupled with hybrid membrane bioreactor. J. Chem. Eng. 2024, 485, 149705. [Google Scholar] [CrossRef]
  2. Ting, W.; Tan, I.; Salleh, S.; Wahab, N. Application of water hyacinth (Eichhornia crassipes) for phytoremediation of ammoniacal nitrogen: A review. J. Water Process Eng. 2018, 22, 239–249. [Google Scholar] [CrossRef]
  3. Edwards, T.M.; Puglis, H.J.; Kent, D.B.; Durán, J.L.; Bradshaw, L.M.; Farag, A.M. Ammonia and aquatic ecosystems—A review of global sources, biogeochemical cycling, and effects on fish. Sci. Total Environ. 2024, 907, 167911. [Google Scholar] [CrossRef] [PubMed]
  4. Zhu, Y.; Chang, H.; Yan, Z.; Liu, C.; Liang, Y.; Qu, F.; Liang, H.; Vidic, R.D. Review of ammonia recovery and removal from wastewater using hydrophobic membrane distillation and membrane contactor. Sep. Purif. Technol. 2024, 328, 125094. [Google Scholar] [CrossRef]
  5. Soliman, R.; Hamza, R.A.; Iorhemen, O.T. Biofilm-based hybrid systems for enhanced brewery wastewater treatment—A review. J. Water Process Eng. 2024, 58, 104763. [Google Scholar] [CrossRef]
  6. Murshid, S.; Antonysamy, A.; Dhakshinamoorthy, G.; Jayaseelan, A.; Pugazhendhi, A. A review on biofilm-based reactors for wastewater treatment: Recent advancements in biofilm carriers, kinetics, reactors, economics, and future perspectives. Sci. Total Environ. 2023, 892, 164796. [Google Scholar] [CrossRef]
  7. Hu, Y.; Mukherjee, M.; Cao, B. Biofilm-Biology-Informed Biofilm Engineering for Environmental Biotechnology. In Introduction to Biofilm Engineering; ACS Publications: Washington, DC, USA, 2019; Volume 3, pp. 59–82. [Google Scholar] [CrossRef]
  8. Espinosa-Ortiz, E.J.; Gerlach, R.; Peyton, B.M.; Roberson, L.; Yeh, D.H. Biofilm reactors for the treatment of used water in space: Potential, challenges, and future perspectives. Biofilm 2023, 6, 100140. [Google Scholar] [CrossRef]
  9. Jiang, S.; Shang, X.; Chen, G.; Zhao, M.; Kong, H.; Huang, Z.; Zheng, X. Effects of regular zooplankton supplement on the bacterial communities and process performance of biofilm for wastewater treatment. J. Environ. Manag. 2023, 345, 118933. [Google Scholar] [CrossRef]
  10. Mustafa, H.M.; Hayder, G. Cultivation of S. molesta Plants for Phytoremediation of Secondary Treated Domestic Wastewater. Ain Shams Eng. J. 2021, 12, 2585–2592. [Google Scholar] [CrossRef]
  11. Rahman, S.A.A.; Priyadharsini, P.; Marimuthu, C.; Sridhar, S.; Arun, J. Chapter 1—Bioremediation, phytoremediation, and mycoremediation of wastewater. Dev. Wastewater Treat. Res. Process. 2024, 1–12. [Google Scholar] [CrossRef]
  12. Soni, K.; Priyadharsini, P.; Dawn, S.S.; Nirmala, N.; Santhosh, A.; Ashima, B.; Arun, J. Phytoremediation of Metals and Radionuclides. In Modern Approaches in Waste Bioremediation; Springer International Publishing: Berlin/Heidelberg, Germany, 2023; pp. 151–164. [Google Scholar] [CrossRef]
  13. He, X.; Zhang, S.; Lv, X.; Liu, M.; Ma, Y.; Guo, S. Eichhornia crassipes-rhizospheric biofilms contribute to nutrients removal and methane oxidization in wastewater stabilization ponds receiving simulative sewage treatment plants effluents. Chemosphere 2023, 322, 138100. [Google Scholar] [CrossRef] [PubMed]
  14. Lu, B.; Xu, Z.; Li, J.; Chai, X. Removal of water nutrients by different aquatic plant species: An alternative way to remediate polluted rural rivers. Ecol. Eng. 2018, 110, 18–26. [Google Scholar] [CrossRef]
  15. Parihar, A.; Malaviya, P. Textile wastewater phytoremediation using Spirodela polyrhiza (L.) Schleid. assisted by novel bacterial consortium in a two-step remediation system. Environ. Res. 2023, 221, 115307. [Google Scholar] [CrossRef]
  16. Ren, Z.; Li, K.; Zhou, H.; Li, X.; Wang, Z.; Wang, H.; Han, S. The application of an integrated two-stage biofilm reactor treating dispersed domestic wastewater. J. Environ. Chem. Eng. 2022, 10, 108859. [Google Scholar] [CrossRef]
  17. Song, Z.; Hao, S.; Zhang, L.; Fan, Z.; Peng, Y. High-rate nitrogen removal by partial nitritation/anammox with a single-stage membrane-aerated biofilm reactor. J. Environ. Manag. 2024, 349, 119581. [Google Scholar] [CrossRef]
  18. Hu, Y.; Wang, J.; Shi, J.; Yang, Y.; Ji, J.; Chen, R. A review of electro-conductive membrane enabled electrochemical anaerobic membrane bioreactor process for low-carbon wastewater treatment. J. Environ. Chem. Eng. 2024, 12, 113494. [Google Scholar] [CrossRef]
  19. Wang, S.; Liu, H.; Gu, J.; Zhang, M.; Liu, Y. Towards carbon neutrality and water sustainability: An integrated anaerobic fixed-film MBR-reverse osmosis-chlorination process for municipal wastewater reclamation. Chemosphere 2022, 287, 132060. [Google Scholar] [CrossRef]
  20. Zulkifli, M.; Abu Hasan, H.; Abdullah, S.R.S.; Muhamad, M.H. A Review of ammonia removal using a biofilm-based reactor and its challenges. J. Environ. Manag. 2022, 315, 115162. [Google Scholar] [CrossRef]
  21. Zulkifli, M.; Abu Hasan, H.; Abdullah, S.R.S.; Othman, A.R. Adaptation of Effective Consortium Bacteria for Ammonia Removal from Domestic Wastewater using Moving Bed Biofilm Reactor. Mater. Today Proc. 2023. [Google Scholar] [CrossRef]
  22. Van de Walle, A.; Kim, M.; Alam, K.; Wang, X.; Wu, D.; Dash, S.R.; Rabaey, K.; Kim, J. Greywater reuse as key enabler for improving urban wastewater management. Environ. Sci. Ecotechnol. 2023, 16, 100277. [Google Scholar] [CrossRef]
  23. Jagaba, A.; Kutty, S.; Lawal, I.; Abubakar, S.; Hassan, I.; Zubairu, I.; Umaru, I.; Abdurrasheed, A.; Adam, A.; Ghaleb, A.; et al. Sequencing batch reactor technology for landfill leachate treatment: A state-of-the-art review. J. Environ. Manag. 2021, 282, 111946. [Google Scholar] [CrossRef] [PubMed]
  24. Xiong, J.; Zheng, Z.; Yang, X.; He, J.; Luo, X.; Gao, B. Mature landfill leachate treatment by the MBBR inoculated with biocarriers from a municipal wastewater treatment plant. Process Saf. Environ. Prot. 2018, 119, 304–310. [Google Scholar] [CrossRef]
  25. Saxena, V.; Padhi, S.K.; Jhunjhunwala, U. Treatment of domestic sewage and leachate using a moving bed hybrid bioreactor. Environ. Technol. Innov. 2021, 24, 101998. [Google Scholar] [CrossRef]
  26. Ng, Y.S.; Juinn, D.; Chan, C. The role and effectiveness of monoculture and polyculture phytoremediation systems in fish farm. RSC Adv. 2021, 11, 13853–13866. [Google Scholar] [CrossRef] [PubMed]
  27. Kumar, S.; Deswal, S. Phytoremediation capabilities of Salvinia molesta, water hyacinth, water lettuce, and duckweed to reduce phosphorus in rice mill wastewater. Int. J. Phytoremediation 2020, 22, 1097–1109. [Google Scholar] [CrossRef]
  28. Zainuddin, N.A.; Md Din, M.F.; Abdul Halim, K.; Abdul Salim, N.A.; Elias, S.H.; Mat Lazim, Z. The Phytoremediation using Water Hyacinth and Water Lettuce: Correlation between Sugar Content, Biomass Growth Rate, and Nutrients. J. Kejuruter. 2022, 34, 915–924. [Google Scholar] [CrossRef]
  29. Sayanthan, S.; Hasan, H.A.; Abdullah, S.R.S. Floating Aquatic Macrophytes in Wastewater Treatment: Toward a Circular Economy. Water 2024, 16, 870. [Google Scholar] [CrossRef]
  30. Nurdin, M.I.; Sukasri, A.; Damayanti, D. Efisiensi bio-ball pada teknologi fitio-biofilm dalam penurunan kadar ammonia pada air limbah domestik. SPIN-J. Kim. Pendidik. Kim. 2023, 5, 166–176. [Google Scholar] [CrossRef]
  31. Chen, T.; Yang, J.; Huang, B.; Liu, W.; Lu, C. Combined process of biofilm+roots for aquaculture wastewater remediation. IOP Conf. Ser. Earth Environ. Sci. 2020, 508, 012102. [Google Scholar] [CrossRef]
  32. Ticllasuca, A.; Matamoros, M.C.; Condori, E.S.; Román, F.T. Evaluation of efficiency of an integrated biofilm and phytoremediation system with Nasturtium officinale for the treatment of municipal wastewater in Huancavelica. Tayacaja 2021, 4, 22–28. [Google Scholar] [CrossRef]
  33. Utami, A.R. Penurunan kadar fosfat dalam limbah rumah sakit dengan menggunakan reaktor fitobiofilm. J. Teknol. Proses Inovasi Ind. 2018, 3, 17–22. [Google Scholar] [CrossRef]
  34. Imron, M.F.; Firdaus, A.A.F.; Flowerainsyah, Z.O.; Rosyidah, D.; Fitriani, N.; Kurniawan, S.B.; Abdullah, S.R.S.; Abu Hasan, H.; Wibowo, Y.G. Phytotechnology for domestic wastewater treatment: Performance of Pistia stratiotes in eradicating pollutants and future prospects. J. Water Process Eng. 2023, 51, 103429. [Google Scholar] [CrossRef]
  35. Auchterlonie, J.; Eden, C.L.; Sheridan, C. The phytoremediation potential of water hyacinth: A case study from Hartbeespoort Dam, South Africa. S. Afr. J. Chem. Eng. 2021, 37, 31–36. [Google Scholar] [CrossRef]
  36. Sayanthan, S.; Abu Hasan, H.; Buhari, J.; Abdullah, S.R.S. Treatment of domestic wastewater using free floating constructed wetlands assisted by Eichhornia crassipes and Pistia stratiotes. J. Ecol. Eng. 2024, 25, 237–252. [Google Scholar] [CrossRef]
Figure 1. (a) Schematic drawing of integrated biofilm-phytoremediation reactor. (b) Top view.
Figure 1. (a) Schematic drawing of integrated biofilm-phytoremediation reactor. (b) Top view.
Water 17 00163 g001
Figure 2. Acclimatization process of the integrated reactor: (a) chemical oxygen demand (COD); (b) ammonia–nitrogen (NH3-N); (c) MLSS and MLVSS.
Figure 2. Acclimatization process of the integrated reactor: (a) chemical oxygen demand (COD); (b) ammonia–nitrogen (NH3-N); (c) MLSS and MLVSS.
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Figure 3. NH3-N removal at various initial concentrations.
Figure 3. NH3-N removal at various initial concentrations.
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Figure 4. Average removal of COD.
Figure 4. Average removal of COD.
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Figure 5. Average removal of PO43−.
Figure 5. Average removal of PO43−.
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Table 1. Information of the two phases of processes in an integrated biofilm-phytoremediation reactor.
Table 1. Information of the two phases of processes in an integrated biofilm-phytoremediation reactor.
PhaseDays of OperationOperating ConditionsInitial Concentration *
NH3-NCODPO43−pHSSDO
I24Acclimatization Stage I; using domestic wastewater0.11–22.820–78-6–733–82-
83Acclimatization Stage II; using synthetic wastewater<10<200-5–65–137-
II69NH3-N Concentration 1 (C1)11–13 28–611.98–4.34637–40 2.67–5.66
23NH3-N Concentration 2 (C2)9–110–581.94–5.875–739–1691.15–6.54
17NH3-N Concentration 3 (C3)3–571–152 1.76–5.935–6 19–672.84–5.68
Note: * All parameter units in mg/L except pH. -: Not recorded.
Table 2. The details of the operation of an integrated biofilm-phytoremediation reactor in Phase II.
Table 2. The details of the operation of an integrated biofilm-phytoremediation reactor in Phase II.
InfluentThe Initial Concentration of Raw Domestic Wastewater
R1A tank of moving bed biofilm reactor (MBBR) containing Hexafilter media
Output R1The effluent of R1 after 24 h and the remaining 12 L is transferred into the R2 tank
R2A tank of phytoremediation containing water hyacinth
Output R2The effluent of the overall performance of the integrated reactor after another 24 h
Table 3. Monthly average concentration characterization of raw domestic wastewater.
Table 3. Monthly average concentration characterization of raw domestic wastewater.
ParameterDomestic Wastewater Concentration
Q1 StdQ2StdQ3StdQ4Std
pH6.410.096.470.057.180.106.180.60
SS (mg/L)391.15315.135015.136128.73
NH3-N (mg/L)15.183.9813.247.3822.632.4226.126.93
PO43− (mg/L)3.191.184.560.765.410.395.410.85
NO2-N (mg/L)0.0970.070.1910.30.0960.060.2460.2
NO3-N (mg/L)3.91.423.61.964.31.234.81.72
COD (mg/L)4926.666649.221608.7415339.05
Note: Q1 (average for January to March); Q2 (average for April to June); Q3 (average for July to September); Q4 (average for October to December).
Table 4. Summary of Phase I: acclimatization process of the integrated reactor.
Table 4. Summary of Phase I: acclimatization process of the integrated reactor.
ParameterPhase I: Acclimatization Process
Stage I (Domestic Wastewater)Stage II (Synthetic Wastewater)
pHInfluent6.12–7.615.90–6.83
Effluent6.02–7.455.71–6.76
SS (mg/L)Influent33–825–137
Effluent14–491–78
NH3-N (mg/L)Influent0.11–22.822.12–10.49
Effluent0.01–22.690.02–1.72
Removal (%)0–95.668.7–99.6
COD (mg/L)Influent0–7821–200
Effluent0–690–35
Removal (%)0–10051–100
MLSS (mg/L)
  • Growth from 100 to 3530
  • Consistently >3000 after day 91
MLVSS (mg/L)
  • Growth from 110 to 3980
  • Remained stable >1000 after day 59
Table 5. Summary of Phase II: removal of selected parameters under the variation of the initial NH3-N concentration.
Table 5. Summary of Phase II: removal of selected parameters under the variation of the initial NH3-N concentration.
Parameters C1C2C3
NH3-NInfluent (mg/L)12.66 9.95 4.05
Output R1 (%)819492
Output R2 (%)899899
CODInfluent (mg/L)40 17 123
Output R1 (%)728066
Output R2 (%)97100100
PO43−Influent (mg/L)3.28 3.55 4.34
Output R1 (%)195722
Output R2 (%)648066
Table 6. Comparative performance of integrated biofilm-phytoremediation process with previous studies.
Table 6. Comparative performance of integrated biofilm-phytoremediation process with previous studies.
TreatmentType of WastewaterAquatic PlantMedia CarriersInitial Concentration (mg/L)Pollutant Removals (%)References
Phyto-Biofilm DomesticWater hyacinthHexafilterNH3-N: 4.05–12.66
COD: 17–123
PO43−: 3.28–4.34
NH3-N: 89–99
COD: 97–100
PO43−: 64–80
This study (2025)
Phyto-Biofilm DomesticWater hyacinthBio-ballNH3-N: 4082.3NH3-N: 92.8[30]
Phyto-Biofilm AquacultureWatercressHemp cloth, cotton cloth, silk screen nylon clothNH3-N: 9.57
COD: 125.6
PO43−: 6.09
NH3-N: 82.4
COD: 84.6
PO43−: 57.8
[31]
Phyto-Biofilm MunicipalWatercressFiltering material (Calcareous stuff)COD: 344.6COD: 67[32]
Phyto-Biofilm HospitalWater hyacinthBroken tiles, black sandPO43−: 2.21–3.12PO43−: 80[33]
MBBRSynthetic domestic-HexafilterNH3-N: 10
COD: 236–320
NH3-N: 96.5
COD: 95.9
[21]
PhytoremediationDomesticWater lettuce-NH3-N: 4.4
COD: 226
TP: 0.43
NH3-N: 46.4
COD: 99.8
TP: 80.4
[34]
PhytoremediationDam waterWater hyacinth-PO43−: 0.73–2.1 PO43−: 93.8 [35]
PhytoremediationDomesticWater hyacinth-NH3-N: 6.62
COD: 37
PO43−: 2.54
NH3-N: 97.4
COD: 54
PO43−: 68.5
[36]
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Buslima, F.A.; Abu Hasan, H.; Alias, J.; Jaganathan, J.S.; Buhari, J.; Subramanian, S.V.; Abdullah, S.R.S. Performance of Integrated Biofilm-Phytoremediation Process in Reclaiming Water from Domestic Wastewater. Water 2025, 17, 163. https://doi.org/10.3390/w17020163

AMA Style

Buslima FA, Abu Hasan H, Alias J, Jaganathan JS, Buhari J, Subramanian SV, Abdullah SRS. Performance of Integrated Biofilm-Phytoremediation Process in Reclaiming Water from Domestic Wastewater. Water. 2025; 17(2):163. https://doi.org/10.3390/w17020163

Chicago/Turabian Style

Buslima, Fairuz Afiqah, Hassimi Abu Hasan, Jahira Alias, Jaga Sahsiny Jaganathan, Junaidah Buhari, Suriya Vathi Subramanian, and Siti Rozaimah Sheikh Abdullah. 2025. "Performance of Integrated Biofilm-Phytoremediation Process in Reclaiming Water from Domestic Wastewater" Water 17, no. 2: 163. https://doi.org/10.3390/w17020163

APA Style

Buslima, F. A., Abu Hasan, H., Alias, J., Jaganathan, J. S., Buhari, J., Subramanian, S. V., & Abdullah, S. R. S. (2025). Performance of Integrated Biofilm-Phytoremediation Process in Reclaiming Water from Domestic Wastewater. Water, 17(2), 163. https://doi.org/10.3390/w17020163

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