Bacterial Regrowth Potential Research Articles

Effect of flow fluctuation on water pollution in drinking water distribution systems

The detachment of biofilm caused by changes in hydraulic conditions is an essential reason for the pollution of water in the drinking water distribution system (DWDS). In this research, the effect of flow fluctuation on bulk water quality was studied. The turbidity, iron concentration, manganese concentration, the total number of bacteria, biodegradable dissolved organic carbon (BDOC), bacterial community structure, and pathogenic genes in bacteria of bulk water were analyzed. The results indicate that the detachment of biofilm caused by fluctuant flow and reverse flow (especially instant reverse flow) can lead to the pollution of water. Throughout the entire experimental period, the turbidity under fluctuant flow velocity is 4.92%∼49.44% higher than that under other flow velocities. BDOC concentration is 5.68%∼53.99% higher than that under low and high flow velocities. The flow fluctuation increases bacterial regrowth potential (BRP) and reduces the biological stability of the bulk water. Low flow velocity is more conducive to the expression of pathogenic functional genes. In the short term, the water quality under low flow velocity is the best. Nevertheless, in a long-term operation (about seven days later), the water quality under high flow velocity is better than that under other flow velocities. This research brings new knowledge about the fluctuant hydraulic conditions on the bulk water quality within the DWDS and provides data support for stable drinking water distribution.

Impact of invertebrates on water quality safety and their sheltering effect on bacteria in water supply systems

Invertebrates in drinking water not only affect human health, but also provide migration and shelter for pathogenic microorganisms. Their residues and metabolites also produce DBPs (disinfection by-products), which have adverse effects on the health of residents. In this study, the contributions of the rotifers and nematodes to the BDOC (biodegradable dissolved organic carbon), BRP (bacterial regrowth potential) and DBPs in drinking water were explored, and the sheltering effects of chlorine-resistant invertebrates on indigenous bacteria and pathogenic bacteria were studied, and the health and safety risk of invertebrates in drinking water was also assessed. The contributions of rotifer BAPs (biomass-associated products), UAPs (utilization-associated products) of rotifer, and nematode BAPs to the BRP were 46, 1240, and 24 CFU/mL. Nematodes were found to have a sheltering effect on indigenous bacteria and pathogenic bacteria, allowing them to resist chlorine disinfection and UV (ultraviolet) disinfection. When subjected to a UV dose of 40 mJ/cm2, the inactivation rates of indigenous bacteria and three pathogenic bacteria decreased by 85% and 39–50% when bacteria were sheltered by the living nematodes; while decreased by 66% and 15–41% when they were sheltered by nematode residue. The safety risk posed by invertebrates in the drinking water was mainly due to their ability to promote bacterial regeneration and carry bacteria. This study aims to provide a theoretical basis and technical support for the risk control of invertebrates' pollution, and provides references for ensuring the safety of drinking water and formulating standards for the levels of invertebrates in drinking water.

Enhancement of photocatalytic-based processes by mono- and bimetallic (CuPd) rutile loaded nanoparticles for antibiotic resistance genes and facultative pathogenic bacteria removal

The aim of the study was the strong reduction of facultative pathogenic bacteria (FPB), and clinically relevant antibiotic resistance genes (ARGs) from secondary effluent. To evaluate the ARGs removal efficiency comparative study ofindividual unit processes and combined AOPs has been performed. The present work investigated: i) removal of selected ARGs, namely blaTEM, ermB, qnrS, tetM, five FPB as well as 16S rDNA and the integrase gene intl1 involved in horizontal gene transfer; ii) bacterial regrowth potential after treatment; (iii) the removal of the total genomic DNA content, by mono- and bimetallic TiO2-CuPd rutile photocatalysts under visible light radiation in real secondary effluent.The nanoparticles were characterized by UV–vis, XRD, HRTEM, Raman and XPS. TiO2-CuPd/VIS inactivation gives the highest (more than 2 log units removal) efficiency for almost all targets (blaTEM, ermB, tetM, intl 1, and 16S rRNA) compared to monometallic catalysts. The highest efficiency toward blaTEM was achieved after ozonation and TiO2-CuPd/O3/VIS (3.22 and 3.23 LRV, respectively). It was found that despite similar FPB inactivation, lower DNA destruction was found after O3 compared to TiO2-CuPd/O3/VIS treatment. The blaTEM and enterococci were completely removed during TiO2-CuPd/O3/Vis and TiO2-Cu/O3/Vis. While, catalytic ozonation leads to only slightly blaTEM removal (0.64 and 0.44 LRV for TiO2-CuPd/O3 and TiO2-Cu/O3, respectively). Photocatalytic ozonation with the application of TiO2-CuPd leads to significant removal of FPB and ARGs due to synergistic effect between Pd and Cu, which leads to acceleration of ozone – catalysts reaction. Photocatalytic ozonation has the greatest potential giving promising possibilities for eliminating AMR.

Response of Algal–Bacterial Regrowth Characteristics to the Hypochlorite in Landscape Ponds Replenished with Reclaimed Water

Sodium hypochlorite was widely used as a supplementary disinfectant in reclaimed water (RW) production during the COVID-19 epidemic. It is well known that the chlorination of RW results in a relatively high bacterial regrowth potential in pipeline systems. However, the algal growth and algal–bacterial interactions would be another concern in RW-replenished surface water with light irradiation. In this study, microcosmic experiments were used to explore the impact of hypochlorite on the algae–bacteria community, including the influence of hypochlorite on algal–bacterial regrowth, microbial community structure, and the specific bacteria that can survive chlorination. Results demonstrated that algal growth potential could be promoted after chlorination of the RW, and bacteria abundance increased along with an increase in algal density, which is probably related to DOM decomposition by chlorine oxidation. Additionally, the characteristics of the bacterial community were altered. It is more likely that phytospheric bacteria will survive chlorination. It was discovered that the secondary risks of chlorine disinfection include the growth of algae in addition to bacterial regeneration, which is an extension of the common perception. As a consequence, when chlorinated reclaimed water is used as a supplement for urban landscape ponds, particular attention should be paid to controlling bio-available organic matter induced by reactive chlorine, as well as the algal bloom, to decrease the risk of pathogen transmission.

Regrowth potential of chlorine-resistant bacteria in drinking water under chloramination

The regrowth of chlorine-resistant bacteria in drinking water can deteriorate water quality. The study evaluated the relationship between organic carbon and the regrowth potential of chlorine-resistant bacteria remaining in chloraminated water samples. The results showed that the community structure of bacteria changed with the increase of chloramine dosage. The order in which organic carbon utilized by bacteria was affected by the composition of bacterial community. The biodegradable dissolved organic carbon (BDOC), assimilable organic carbon (AOC), bacterial regrowth potential (BRP) and total cell concentration (TCC) in cultivated water sample after disinfection with 1.8 mg/L chloramine increased form 0.22 mg/L, 33.68 µg/L, 2.70 × 105 cells/mL and 3.48 × 104 cells/mL before cultivation to 1.20 mg/L, 193.90 µg/L, 4.74 × 105 cells/mL and 1.46 × 105 cells/mL, respectively. The increase of TCC did not result in the decrease of BDOC, AOC and BRP in the cultivated water samples. The results showed that other biodegradable organic carbon in chloraminated water samples assimilated by residual chlorine-resistant bacteria besides AOC, BDOC, and organic carbon assimilated by indigenous bacteria. AOC, BDOC, and BRP indicators used to characterize the biostability of drinking water were not enough to accurately assess the regrowth potential of chlorine-resistant bacteria remaining in drinking water. It is suggested to supplement the index of TCC in cultivated water samples, which might be able to more accurately evaluate the regrowth potential of chlorine-resistant bacteria remaining in drinking water.

Application of model fitting technique to enhance bacterial regrowth potential (BRP) measurement for drinking water supply monitoring

AbstractThe bacterial regrowth potential (BRP) method was utilised to indirectly measure the assimilable organic carbon (AOC) as an indicator for the assessment of the microbial regrowth potential in drinking water distribution systems. A model using various microbial growth parameters was developed in order to standardise the experimental interpretation for BRP measurement. This study used 82 experimental BRP data sets of water samples collected from the water treatment plant to locations (customer taps) in the distribution system. The data were used to model the BRP process (growth curve) by a data fitting procedure and to obtain a best-fitted equation. Statistical assessment and validation of the model obtained equation by fitting these 82 sets of data were conducted, and the results show average R2 values were 0.987 for treated water samples (collected at the plant prior to chlorination) and 0.983 for tap water (collected at the customer taps). The F values obtained from the F-test are all exceeded their corresponding F critical values, and the results from the t-test also showed a good outcome. These results indicate this model would be successfully applied in modelling BRP in drinking water supply systems.

Microplastics as carbon-nutrient sources and shaper for microbial communities in stagnant water

Microplastics (MPs) are emerging pollutants as vectors for microbial colonization, but their role as nutrients sources for microbial communities has rarely been reported. This study explored the impact of six types of MPs on assimilable organic carbon (AOC) and microbial communities over eight weeks. The following were the primary conclusions: (1) MPs contributed to AOC increment and subsequently increased bacterial regrowth potential. The maximum AOC reached 722.03 μg/L. The increase in AOC formation corresponded to AOC NOX, except in PVC samples where AOC P17 primarily increased. (2) The MPs accelerated bacterial growth and changed the bacterial distribution between the biofilm and water phases. A high MP surface-area-to-volume ratio or low MPs density contributed to bacterial accumulation and biofilm formation around the plastisphere, thereby decreasing the relative microbial proportion in the water phase. (3) High-throughput sequencing and scanning electron microscope revealed that different MPs shaped various microbial communities temporally and spatially. (4) Biofilm formatting and formatted models were established and simulated to explain the kinetic interaction between the AOC and bacteria inhabiting the plastisphere. Finally, the challenges that plastic-deprived AOC represent in terms of anti-bacterial measures and chemical safety are discussed.

Quantification of biodegradable natural organic matter (NOM) fractions and its impact on bacterial regrowth in a South African Water Treatment Plant

Natural organic matter (NOM) contributes to bacterial regrowth during potable water treatment and supply. Most conventional water treatment plants insufficiently remove the biodegradable dissolved organic (BDOC) NOM fraction. The presence of labile BDOC in water creates conducive conditions for bacterial regrowth. To reduce NOM and the bacterial regrowth potential (BRP) in water, the study aimed at establishing which of the NOM polarity fractions are biodegradable and if the BRP (enumerated according to the heterotrophic plate count [HPC]) method) can be correlated to biodegradability. Specific ultraviolet absorbance (SUVA) was used to characterise source and treated water NOM fractions (i.e. hydrophilic [Hpi], transphilic [Tpi] and hydrophobic [Hpo]) obtained through the modified polarity rapid assessment method (m-PRAM). The source and treated water SUVA values of the Hpi and Hpo were on average, 3.88 L/mg.m and 2.04 L/mg.m, respectively. The Hpi and Tpi fractions on the source and treated were the most biodegradable fractions, with mean BDOC values ranging between 29.22%, and 35.75 %. The high BDOC of the Tpi and Hpi NOM substantially contributed to BRP by up to 121.4 × 103-197.4 × 103 CFU/mL, respectively. The strong correlation (R2 > 0.96) between BRP and BDOC allows for the effective management of water treatment and supply processes, particularly for microbial control.

Comparison between ferrihydrite adsorption and full-scale advanced drinking water treatment processes for controlling bacterial regrowth potential

Bacterial regrowth in drinking water systems is a threat to public health. In this study, ferrihydrite (Fh) adsorption was compared with advanced drinking water treatment processes (ADWTP) during one and a half years of sampling to test the reduction in assimilable organic carbon (AOC) and bacterial regrowth potential (BRP). Dissolved organic matter (DOM) was removed by Fh through ligand exchange and electrostatic interaction. The DOM removal was higher below pH 6 due to protonation of Fh surfaces. The ADWTP exhibited higher removal rates of DOM than Fh and lower phosphate removal rates than Fh. Excitation-emission matrix (EEM) and size exclusion chromatography (SEC) revealed that Fh removed aromatic DOM larger than 1000 Da, while the biological activated carbon (BAC) of ADWTP could remove DOM smaller than 1000 Da. These differences of organic compositions resulted in the lowest AOC of BAC treated water, and the lowest BRP of Fh-treated water, indicating that it was the most biostable water. Phosphate addition experiments illustrated that phosphorus was the primary rate limiting nutrient, indicating that the higher phosphate removal of Fh made it possible to produce waters with lower BRP than ADWTP. Therefore, BRP is considered to be a better indicator of bacterial regrowth than AOC when phosphorus is a rate-limiting nutrient, as is the case with the Fh treatment.

Assessing pretreatment and seawater reverse osmosis performance using an ATP-based bacterial growth potential method

Various bacterial growth potential (BGP) methods have been developed recently to monitor biofouling in seawater reverse osmosis (SWRO) systems such as assimilable organic carbon and bacterial regrowth potential. However, the relationship between these methods and biofouling in SWRO desalination plants has not yet been demonstrated. In this research, an attempt is made to investigate if a correlation exists between BGP of SWRO feed water and the chemical cleaning frequency in SWRO plants using an ATP-based BGP method employing an indigenous microbial consortium. Using ATP-based BGP method at 5 different seawater locations showed low variations of bacterial yield.The BGP method was applied to assess the pretreatment performance of three full-scale SWRO plants with different pretreatment processes. Dual media filtration (DMF) showed the highest BGP removal (>50%) in two SWRO plants. Removal of BGP and hydrophilic organic carbon in dissolved air floatation combined with ultrafiltration was similar to the removal achieved with DMF in combination with inline coagulation. For the three SWRO plants investigated, a higher BGP in SWRO feed water corresponded to a higher chemical cleaning frequency. However, more data is required to confirm if a real correlation exists between BGP and biofouling in SWRO plants.

Exploring the biological stability situation of a full scale water distribution system in south China by three biological stability evaluation methods

Bacterial regrowth especially opportunistic pathogens regrowth and contamination in drinking water distribution systems (DWDS) have become an emerging threat to public health in the whole world. To explore bacterial regrowth and biological stability, assimilable organic carbon (AOC), biodegradable dissolved organic carbon (BDOC) and bacterial regrowth potential (BRP) were evaluated in a full scale DWDS and bench tests in South China. A significant correlation between BRP and AOC in both water treatment processes (WTP) and DWDS was obtained. For BRP and BDOC, the correlation was more significant in WTP than in DWDS. Both AOC and BRP were significantly correlated with UV254, total organic carbon (TOC), and heterotrophic plate count (HPC) (p < 0.01), whereas BDOC was only significantly associated with UV254, temperature and chlorine residual (p < 0.01). Through a bench test, when chlorine was higher than 0.5 mg/L, the HPC level was low and AOC concentration almost unchanged. On contrary the HPC level increased quickly and declined slightly, with chlorine lower than 0.15 mg/L, which was in accordance with the large amount of biological stability data obtained from DWDS. Through another bench test, the HPC level was positively correlated to AOC concentration and when AOC was below 135 μg/L, the growth rate of HPC was low, which was verified by the analysis of biological stability data from DWDS.

Modeling the supercritical carbon dioxide inactivation of Staphylococcus aureus, Escherichia coli and Bacillus subtilis in human body fluids clinical waste

Human body fluids clinical waste poses a challenge to healthcare facilities because of the presence of infectious pathogenic microorganisms, leading concern for an effective sterilization method to eliminate the infectious threat for safe handling and disposal. In the present study, the supercritical carbon dioxide (SC-CO2) was utilized to sterilize human blood waste with varying pressure and temperature for a treatment time of 5–90min. Modified Gompertz equation was employed to elucidate Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis-vegetative cell) inactivation curve in SC-CO2 sterilized human blood waste. It was observed that the experimental data was well fitted with the predicted value obtained from modified Gompertz equation. The SC-CO2 sterilization efficiency was compared with the steam autoclave treatment based on bacterial regrowth potential and scanning electron microscope image analyzes. The absence of bacterial regrowth and physicochemical destruction of bacterial cells revealed that SC-CO2 is an efficient sterilization technology to treat human blood waste. Thus, SC-CO2 sterilization method could be utilized to sterilize human blood waste in a healthcare facility to improve hospital hygiene by eliminating infectious exposure of human body fluids clinical waste, and to conduct safe handling and management of human body fluids clinical waste.

Multiple views of biological stability and optimized coagulation in the control of biostability in traditional water treatment processes: a pilot test

This study investigated biological stability in a pilot test of traditional water treatment processes in eastern China. The variations of assimilable organic carbon, biodegradable dissolved organic carbon, bacterial regrowth potential, and total phosphorus were analyzed, and the relationships among them were studied. High-purity aluminum sulfate was added as a coagulant, and the corresponding removal efficiencies of the coagulation–sedimentation unit and the sand filtration unit were evaluated. The experimental results indicate that the removal efficiencies of the dissolved organic carbon (DOC) and UV254 both increased as the alum dosages increased in the coagulation and sedimentation process. The removal efficiencies of the biostability indicators of the coagulation and sedimentation process were higher than those of the filtration treatment. The bacterial regrowth potential was correlated with DOC concentration, and the introduction of total dissolved phosphorus into the evaluation of biostability is recommended to help confirm the C:P ratio and to select the appropriate strategy for controlling bacterial regrowth. An explanation for the changes in biostability indicators is provided.

Inactivation and regrowth of multidrug resistant bacteria in urban wastewater after disinfection by solar-driven and chlorination processes

Solar disinfection and solar-driven advanced oxidation processes (AOPs) (namely H2O2/sunlight, TiO2/sunlight, H2O2/TiO2/sunlight, solar photo-Fenton) were evaluated in the inactivation of indigenous antibiotic-resistant bacteria (ARB) in real urban wastewater. A multidrug resistant (MDR) Escherichia coli strain isolated from the effluent of the biological process of an urban wastewater treatment plant was the target ARB. The higher inactivation rates (residual density under detection limit, 2CFUmL−1) were achieved with H2O2/TiO2/sunlight (cumulative energy per unit of volume (QUV) in the range 3–5kJL−1, depending on H2O2/TiO2 ratio) and H2O2/sunlight (QUV of 8kJL−1) processes. All investigated processes did not affect antibiotic resistance of survived colonies. Moreover, H2O2/sunlight was compared with conventional chlorination process to evaluate bacterial regrowth potential and particularly the proportion of indigenous MDR E. coli with respect to total indigenous E. coli population. Chlorination (1.0mg Cl2L−1) was more effective than H2O2/sunlight (50mg H2O2L−1) to achieve total inactivation of MDR E. coli (15min Vs 90min) but less effective in controlling their regrowth (24h Vs 48h). Interestingly, the percentage of MDR E. coli in H2O2/sunlight treated samples decreased as incubation time increased; the opposite was observed for chlorinated samples.

Assessment of biological activated carbon treatment to control membrane fouling in reverse osmosis of secondary effluent for reuse in irrigation

Biologically treated secondary effluent (BTSE) is being used increasingly as a source of water for irrigation purposes. Biological activated carbon (BAC) was investigated as a pre-treatment to reduce the organic fouling and biofouling potential of reverse osmosis (RO) membranes for the desalination of a moderately saline BTSE to be used for agricultural purposes. The BAC reduced the organic content through biodegradation by the microorganisms and adsorption by the activated carbon, and subsequent microfiltration (0.1μm PVDF) further reduced the organic content and thus fouling of the RO membrane. The BAC treatment was shown to effectively reduce the biodegradable dissolved organic carbon and assimilable organic carbon contents, and the bacterial regrowth potential, thus confirming its potential for mitigating biofouling of the RO membrane. The improved RO performance demonstrated that this process was effective for reducing the fouling propensity of the BTSE to enable its sustainable application for producing an effluent with a high reuse potential for irrigation purposes. The RO permeate can then be blended with untreated water to produce a product with a suitable inorganic content for irrigation.

Temperature-dependent change of light dose effects on E. coli inactivation during simulated solar treatment of secondary effluent

In this study, simulation of solar disinfection of secondary effluents was performed, to assess the dose effects, as instructed by the reciprocity law. A full factorial experimental design on the operational parameters of the process was performed (time, temperature, bacterial load, light intensity) and three response variables were estimated (disinfection efficiency, regrowth after 24, and 48h). In the 240 disinfection experiments, an erratic behavior was observed in all responses to light exposure, attributed to the combination of both irradiation intensity and temperature during treatment. As a result, the validity of the reciprocity law between light dose and irradiation intensity is challenged. The majority of the cases failed to comply with it, indicating the dependence on temperature conditions, as well as the applied intensity. Dose affected the bacterial regrowth potential after 24 and 48h in a more conventional way. It appears that in order to attain a valid projection of the outcome of solar disinfection in secondary effluent, intensity and dose are not the only parameters to be considered, with temperature also having to be taken under consideration.

A review research of assimilable organic carbon bioassay

Assimilable organic carbon (AOC) is one of the important parameters internationally recognized to assess the biostability of water. Studies at home and abroad on the AOC bioassay’s development are reviewed from three aspects, including the selection of bacterial species for the bioassay, the optimization of inoculation method and incubation condition of water samples, and the evolution of bacterial growth measurement. The relationships between MAP (microbially available phosphorus), BRP (bacterial regrowth potential), and AOC are compared from determination mechanism. Moreover, the new development trend of AOC bioassay is predicted.

Removal of organic matter and phosphate using ferrihydrite for reduction of microbial regrowth potential

Dissolved organic matter (DOM) and phosphate in reclaimed water promote microbial growth in distribution systems and deteriorate water quality. In this study, we tested ferrihydrite (Fh) for its potential to remove both DOM and phosphate in order to control bacterial regrowth. Adsorption kinetics on Fh revealed that phosphate has a higher affinity with Fh than has DOM. The removal efficiency of DOM increased at lower pH. Fourier transform infrared spectroscopy (FT-IR) spectra of freeze-dried Fh showed that adsorbed DOM was rich in carboxyl/hydroxyl functional groups, indicating anion exchange at Fh surfaces to be a major mechanism, especially at low pH. Fh preferentially removed DOM greater than 1,000 Da. Specific ultraviolet absorption (SUVA) at 254 nm and DOC results suggest Fh adsorption removes more hydrophilic DOM than the coagulation-sand filtration process. Reduction of bacterial regrowth potential (BRP) by Fh was comparable to that of the coagulation-sand filtration process, which indicated that phosphorus was not the rate-limiting factor of microbial growth.

Destructive and non-destructive methods for biofouling analysis investigated at the Adelaide Desalination Pilot Plant

In preparation for the operation of the 300 ML/day Adelaide Desalination Plant, a pilot plant was constructed to evaluate anticipated operational challenges, such as biofouling. Various methods for the control of biofouling have been proposed, however, in-situ early tools for detection of biofouling conditions in spiral wound reverse osmosis elements remain elusive. The current study investigated the use of novel methods for assessment of biofouling potential, using process stream samples obtained from the Adelaide Desalination Pilot Plant (ADPP). Non-destructive methods, including flow cytometry (FCM) and bacterial regrowth potential (BRP) analysis were used. X-ray photoelectron spectroscopy (XPS) and Time of Flight-Secondary Ion Mass Spectroscopy (ToF-SIMS) analyses were employed during destructive membrane autopsy to compliment the findings of the FCM & BRP. 16S rRNA analysis was undertaken on seawater samples and autopsied membrane elements to evaluate whether sampling of bulk process streams could provide early warning of potential RO membrane biofouling bacteria. BRP analysis allowed for calculation of whether had assimilable organic carbon (AOC) was consumed by biofilm on the membrane or being sloughing from the surface. XPS and ToF-SMIS analysis facilitated detection of polysaccharides and proteins adhered to the membrane surface. ToF-SIMS also allowed for the detection of foreign chemical contaminant (i.e. organosilicone). 16S rRNA analysis identified the bacteria species within the biofilm. It also allowed for non-destructive analysis of the biofilm microbial composition via swabbing of the RO element's exterior case. 16S rRNA analysis of biofilm on the exterior surface of an RO element correlated well with the microbial composition of internal membrane surface biofilm. This finding could assist utilities as a rapid, non-destructive assessment of potentially biofouling species. ► FCM can determine when the RO system is sloughing or producing bacteria. ► FCM confirmed bacterial contamination of the antiscalant solution. ► XPS has the potential to detect polysaccharides and proteins adhered to the membrane surface. ► ToF-SIMS indicated the presence of organosilicone fouling. ► 16S RNA identified bacteria species and biofilm composition via swabbing of the RO.

The application of the Bacterial Regrowth Potential method and Flow Cytometry for biofouling detection at the Penneshaw Desalination Plant in South Australia

As the use of reverse osmosis (RO) for sea water desalination is rapidly expanding in Australia, the detection of biofouling on spiral wound RO membranes is becoming increasingly important for limiting this phenomenon and thus making substantial energy savings. Bacterial Regrowth Potential (BRP) and Flow Cytometry (FCM) were assessed as methods for detecting biofouling rapidly and without need for sacrificing any elements for autopsy. The study was undertaken at the Penneshaw Desalination Plant in South Australia from May 2008 to January 2009. Whilst BRP or FCM alone made interpretation of results difficult, the combination of BRP and FCM analysis provided a potential tool to evaluate membrane biofouling. Biofouling of the RO membrane was present but the extent varied due to feed seawater quality and water temperature. The dynamics of biofilms are complex as adhesion and sloughing of bacteria occur simultaneously. The combination of BRP and FCM techniques revealed sloughing or adhesion of bacteria to the membrane surface.