Comparison of the wastewater treatment performance of continuously and discontinuously mixed high-rate algal ponds at Kingston on Murray.

High-rate algal ponds (HRAPs) incorporate shallow raceway designs and paddlewheel mixing. HRAPs use UV disinfection and the symbiotic environment between microalgal photosynthesis and heterotrophic bacteria for the assimilation of nutrients for efficient wastewater treatment. Mixing of a HRAP provides a homogenous environment and influences both the disinfection of pathogens and algal growth by exposing the wastewater to sunlight. Guidelines require continuous mixing of the HRAP. This study aimed to determine the effect of cessation of mixing for 10 days, on wastewater treatment by comparison with a continuously mixed pond operated over the same period. The period of 10 days was equivalent to the HRAP hydraulic retention time. Samples of inlet and HRAP-treated wastewater were collected from the HRAP at Kingston on Murray. Parameters measured were Escherichia coli, chlorophyll a, total suspended solids (TSS), NH4-N, NO2-N, NO3-N, PO4-P and biochemical oxygen demand (BOD5). The discontinuously mixed and the continuously mixed HRAPs complied with the wastewater effluent guidelines, of an E. coli concentration ≤104 MPN100 mL-1 and a BOD5 of <20 mg L-1. An E. coli log reduction value of >1 was also recorded. This study shows that cessation of mixing for 10 days had no significant effect on HRAP wastewater treatment performance.

Juncus sarophorus, a native Australian species, tolerates and accumulates PFOS, PFOA and PFHxS in a glasshouse experiment.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been identified as emerging contaminants of public health concern. With PFAS now detected globally in a wide range of environments, there is an urgent need for effective remedial treatment solutions at the field scale. Phytoremediation presents a potential remediation strategy for PFAS that would allow efficient and cost-effective remediation at large scales. This study examined the potential for the Australian native wetland plant Juncus sarophorus to tolerate, take up, and accumulate PFOS, PFOA and PFHxS. A 190-day glasshouse experiment was conducted, in which 0, 10 and 100 µg/L each of PFOS, PFOA and PFHxS were used to irrigate J. sarophorus in potted soil. The results suggest that J. sarophorus has a high tolerance to PFAS and is effective at accumulating and transferring PFHxS and PFOA from soils to above ground biomass. Together with its high growth rate, J. sarophorus appears to be, in principle, a suitable candidate for phytoextraction of short-chained PFAS compounds. It is, however, less efficient at uptake of PFOS, owing to the long chain-lengths of this compound and PFOSs' ability to sorb effectively to soils. The total accumulated PFAS mass at the end of the experiment was ~2000 µg/kg biota(wet weight) and ~170 µg/kg biota(wet weight) for soils irrigated with 100 µg/L and 10 µg/L for each PFAS compound, translating into overall PFAS removal rates of 11% and 9%.

Spatial performance assessment of reed bed filtration in a constructed wetland.

Constructed wetlands (CW) are implemented to improve water quality through filtration by plants (macrophytes), which sequester nutrients and contaminants. Macrophyte beds in CWs reduce the speed of water flow, aiming to improve the water quality by sedimentation and filtration with increasing distance from the inflow. Few studies have assessed spatial distribution and accumulation concentrations of nutrients and contaminants in CW macrophytes as a performance indicator for wetland functionality and management. Macrophytes and water were analysed for nutrient and contaminant accumulation in-situ at a stormwater-fed CW and water remediation site in South Australia. During the austral summer, macrophytes were sampled at 36 sites and water at 46 sites selected by a systematic GIS produced grid covering the entire wetland, which determined distance from the inflow for each site. A total of 144 Schoenoplectus validus (stems and roots) macrophyte samples (i.e. carbon-C, nitrogen-N, Trace elements) and 183 water samples (i.e. total suspended solids-TSS, total nitrogen-TN, total carbon-TC, nitrate-NO3-/ nitrite-NO2- and ammonia-NH4+) were analysed. Concentrations of water chemistry parameters that significantly increased with distance away from inflow included; TC (P = 0.0008), TN (P = 0.0001), and NH4+ (P = 0.0001), while there was significant decrease in TSS (P = 0.0001). The macrophyte S. validus significantly decreased in height (P = 0.0001) and biomass (P = 0.03) with distance from the inflow. Spatial mapping of nutrients and contaminants with distance from inflow identified increasing TC and C characteristics from inflow to outflow and identified where TSS were removed from the water column. Through this spatial assessment approach of the Oaklands CW, management has identified problem areas with flow regimes that require further investigation to enhance macrophyte water filtration performance which can be used in CWs elsewhere in the world.

Examination of Australian backyard poultry for Salmonella, Campylobacter and Shigella spp., and related risk factors.

Worldwide, foodborne illness is a significant public health issue in both developed and developing countries. Salmonellosis, campylobacteriosis and shigellosis are common foodborne gastrointestinal illnesses caused by the bacteria Salmonella spp., Campylobacter spp. and Shigella spp. respectively. These zoonotic diseases are frequently linked to eggs and poultry products. The aim of this study was to investigate the presence of these pathogens in Australian backyard poultry flocks and to determine risk factors for these pathogens. Poultry faeces samples were collected from 82 backyards and screened for Salmonella spp., Campylobacter spp. and Shigella spp. using qPCR. A questionnaire was administered to the backyard poultry owners to assess their knowledge regarding management of poultry and eggs and to identify potential risk factors that may contribute to the presence of zoonotic pathogens in the flocks. One composite faecal sample was collected from each backyard (82 samples). Composite sampling here means taking one or more grab samples from a backyard to make up approximately 10 grams. Four per cent of samples, that is 4% backyards tested, were positive for Salmonella spp., 10% were positive for Campylobacter spp. and none were positive for Shigella spp. A higher infection rate was seen in multi-aged flocks (24%) compared with the single-aged flocks (3%). The survey found that many participants were engaging in risky food safety behaviours with 46% of participants responding that they washed their eggs with running water or still water instead of wiping the dirt off with a damp cloth to clean the eggs and 19% stored their eggs at room temperature. This study demonstrated that backyard poultry may pose a potential risk for salmonellosis and campylobacteriosis. Additionally, Australian public health and food safety regulations should be modified and effectively implemented to address the risks associated with backyard poultry husbandry.

Transport and retention of graphene oxide nanoparticles in sandy and carbonaceous aquifer sediments: Effect of physicochemical factors and natural biofilm.

There is a paucity of information regarding the interaction between GONPs and natural aquifer sediments. Therefore, batch and column experiments were carried out to determine the transport, retention and attachment behavior of GONPs with the surfaces of native aquifer sediments. The experiments were performed with sediments comprising contrasting mineralogical features (sand grains, quartz and limestone sediments), at different temperatures, ionic strength and compositions. Uniquely, this research also investigated the effect of natural biofilm on the retention behavior of nanoparticles in porous media. The retention rate of GONPs at 22 °C was higher than at 4 °C. Moreover, there was greater retention of GONPs onto the surfaces of collectors at higher ionic strengths and cation valence. The retention profiles (RPs) of GONPs in pristine porous media at low ionic strength were linear, which contrasted with hyper-exponential shape of RPs at high ionic strength. The size-distribution analysis of retained GONPs showed decreasing particle diameter with increasing distance from the column inlet at high ionic strength and equal diameter at low ionic strengths. The GONP retention rate was higher for natural porous media than for sand, due to the presence of metal oxides heterogeneities. The presence of biofilm on porous media increased the retention rate of GONPs when compared to the porous media in the absence of biofilm.

Changes of viral and prokaryote abundances in a high rate algal pond using flow cytometry detection.

High rate algal ponds (HRAPs) are shallow, mixed systems for wastewater treatment, which use sunlight exposure for disinfection. Little is known regarding the relationships between the bacteria and viruses within HRAP systems. Uniquely, flow cytometry permits the rapid identification of bacterial and viral populations in wastewater samples, separating populations based on genome and particle size. Treated wastewater samples were collected from an HRAP at Kingston on Murray, South Australia. Flow cytometry analysis detected bacterial populations and discriminated virus-like particles (VLP) and large VLP (LVLP). Rapid, short term, fluctuations in the abundance of all three populations were observed. Changes in the abundance of these populations was compared; wastewater composition was used as metadata for the comparisons. Linear regression determined relationships in abundances between bacteria and LVLP (R2 0.2985); LVLP and VLP (R2 0.5829) and bacteria and VLP (R2 0.5778) all with p-values of <0.001. Bacterial, LVLP and VLP abundance positively correlated with each other, indicating potential microbial interactions. Overall, the results suggest a parasitic relationship was occurring and driving the abundances of bacteria and viruses within the system.

Role of biofilm on virus inactivation in limestone aquifers: implications for managed aquifer recharge.

BACKGROUND: Virus, as nano-sized microorganisms are prevalent in aquifers, which threaten groundwater quality and human health wellbeing. Virus inactivation by attachment onto the limestone surfaces is a determining factor in the transport and retention behavior of virus in carbonaceous aquifers. METHODS: In the present study, the inactivation of MS2 -as a model virus- by attachment onto the surfaces of limestone grains was investigated in a series of batch experiments under different conditions such as limestone particle size distribution (0.25-0.50, 0.5-1 and 1-2 mm), treated wastewater and RO water, temperature (4 and 22 °C), initial MS2 concentrations (103-107 PFU/mL) and static and dynamic conditions. The experimental data of MS2 inactivation was also fitted to a non-linear kinetic model with shoulder and tailing. The characteristics of biofilm on the surfaces of limestone aquifer materials were assessed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). RESULTS: The inactivation rate of virus decreased with increasing the adsorbent diameter. Furthermore, virus inactivation was greater at room temperature (22 °C) than 4 °C, in both static and dynamic conditions. The inactivation of virus via attachment onto the limestone aquifer materials in dynamic conditions was higher than under static conditions. In addition, fitting the experimental data with a kinetic model showed that virus inactivation was high at higher temperature, smaller limestone grains and dynamic conditions. Moreover, the experiments with treated wastewater showed that in authentic aqueous media, the virus inactivation was considerably higher than in RO water, due to the presence of either monovalent or divalent cations and surface roughness created by biofilms. CONCLUSION: Finally, in terms of managed aquifer recharge systems, the presence of biofilm increases bacteria and virus retention onto the aquifer surfaces. Graphical abstract.

Effect of bacteria and virus on transport and retention of graphene oxide nanoparticles in natural limestone sediments.

This research was conducted to evaluate the effect of co-transport of different-sized microorganisms on graphene oxide nanoparticles (GONPs) transport and retention in saturated pristine and biofilm-conditioned limestone columns. The transport and retention behavior of GONPs was studied in columns in the presence of MS2 -as a nano-sized- and Escherichia coli (E.coli) -as a micro-sized- microorganisms at low and high ionic strength conditions. Results showed no changes in GONPs transport and retention at high ionic strength in the presence of MS2 or E. coli, which was attributed to the effect of high concentration of divalent cation on aggregation of nanoparticles and microorganisms. Furthermore, simultaneous enhanced transport and decreased retention of GONPs in column was observed in the co-presence of microorganisms at low ionic strength. Results revealed that the main mechanism governing increasing GONPs transport in porous media was occupation of reactive surface sites of collectors by microorganisms, which prevented attachment of nanoparticles. The pre-saturation of columns with MS2 and E. coli caused increasing transport of GONPs in the columns, due to the occupation of surface reactive sites. Moreover, conditioning limestone collectors with natural biofilm resulted in the same rates of nanoparticle elution and retention (i.e., in the presence or absence of microorganisms) by straining of GONPs in the inlet end of columns which shows that the biofilm acts as a bio-filter against discharging nanoparticles into the effluents. Finally, from the obtained results, it can be postulated that the presence of microorganisms in a MAR site causes risk of groundwater pollution by toxic nanoparticles.

A Successful Technique for the Surface Decontamination of Salmonella enterica Serovar Typhimurium Externally Contaminated Whole Shell Eggs Using Common Commercial Kitchen Equipment.

Eggs are a highly nutritious food source used in a wide range of food products. In Australia, eggs are a frequent source of foodborne salmonellosis outbreaks, associated with eggshell contamination with Salmonella enterica serovar Typhimurium (ST). Despite their potentially hazardous nature, raw eggs are often used and consumed in mayonnaise, mousse, ice cream and eggnog. The aim of this study was to develop a shell egg decontamination method that removed ST contamination from the outside of an egg without impacting its usability. The decontamination method was developed by the adaptation of a temperature-controlled water bath (commonly present in kitchens and associated with the sous-vide technique) for the surface decontamination of eggs. The outside of whole eggs was artificially inoculated with two ST strains. The eggs were decontaminated by placing in a sous-vide cooker with the water heated to 57°C. The remaining viable ST present on the whole shell egg, crushed shells, internal egg contents and sous-vide water were enumerated over time by culturing onto XLD agar. The quality of the uncontaminated heat-treated eggs was determined by measuring the Haugh unit, yolk index, albumen pH, thermocoagulation, and stability of foam. A blind control study was conducted to assess the acceptability and usability of the treated eggs by chefs and food handlers for the preparation of mayonnaise. Complete decontamination of ST was achieved by treating eggs for 9 min in the sous-vide cooker (57°C). No statistically significant difference was observed in the quality of treated eggs compared with nontreated eggs using the quality measurements and acceptability score from chefs. This method provides a simple approach that can be adopted by chefs and food handlers to obtain safe eggs before the preparation of raw egg products.

The Combined Effect of pH and Temperature on the Survival of Salmonella enterica Serovar Typhimurium and Implications for the Preparation of Raw Egg Mayonnaise.

Raw egg products are often associated with salmonellosis. The Australian guidelines recommend raw egg mayonnaise to be prepared and stored under 5 °C and adjusted to a pH less than 4.6 or 4.2. Despite these guidelines, a significant amount of salmonellosis outbreaks are recorded annually in Australia. The aim of this study was to investigate the effect of pH and temperature on the survival of Salmonella Typhimurium (ST) in peptone water (PW) and mayonnaise. The pH of PW and mayonnaise was adjusted to 4.2, 4.4 and 4.6 using acetic acid and vinegar, respectively. The PW and mayonnaise were inoculated with ST and incubated at 37 °C, 23 °C, and 4 °C. The survival of Salmonella was determined using the drop plate method. Survival was significantly (p < 0.05) improved at 4 °C. In both mayonnaise and PW, following 24 h, there was no ST growth at pH 4.2. Resuscitation of ST was rapidly observed at 4 °C while complete inactivation was observed at 37 °C at pH 4.2, 4.4, and 4.6 in both PW and mayonnaise. Lower temperatures protected ST from the bactericidal effect of low pH. "The preparation of mayonnaise at pH 4.2 or less and incubating it at room temperature for at least 24 h could reduce the incidence of salmonellosis".

Case study on the effect continuous CO2 enrichment, via biogas scrubbing, has on biomass production and wastewater treatment in a high rate algal pond.

Microalgae grown in high rate algal ponds (HRAP) treating wastewater are considered a promising feed for biofuel production. Biomass productivity is often considered to be limited by carbon availability, with the addition of CO2 being the proposed solution. Biogas from anaerobic wastewater treatment potentially provides a cheap, co-located CO2 source. Two identical 223 m2 HRAPs were constructed at Melbourne Water's Western Treatment Plant, where biogas from an anaerobic lagoon is used to generate electricity. One HRAP was fed secondary treated wastewater that had been enriched with CO2 recovered from the biogas using industry standard biogas scrubbers, the Enriched HRAP, while the other HRAP was fed the same wastewater expect it had by passed the biogas scrubbers, the Control HRAP. The biomass production and wastewater treatment performance of the two HRAPs was compared over 12 months. The inlet to the Enriched HRAP had significantly higher free CO2 and inorganic carbon, 175.00 ±â€¯49.30 mg L-1 and 110.00 ±â€¯10.2 mg L-1, than the inlet to the Control HRAP, 9.30 ±â€¯7.08 mg L-1 and 89.62 ±â€¯5.12 mg L-1. There were no significant differences in biomass production between the HRAPs as measured by dry matter, particulate organic carbon or nitrogen. Chlorophyll a was statistically higher in the Enriched HRAP, however, this measurement is potentially unreliable. Regarding wastewater treatment, only total nitrogen and ammonium removal differed significantly between the HRAPs, with the Control HRAP, 59.13 ±â€¯21.13% and 76.46 ±â€¯32.33%, slightly outperforming the Enriched HRAP, 53.52 ±â€¯17.41% and 68.76 ±â€¯31.17%. Overall, neither biomass production nor wastewater treatment was meaningfully improved by CO2 enrichment, however, wastewater treatment was still effective in both HRAPs.

Nitrification performance of high rate nitrifying trickling filters at low ammonia concentrations: does the aspect ratio matter?

Nitrifying trickling filters (NTFs) are often introduced to pre-treat waters before chlorination process, to reduce the ammonia-driven chlorine consumption in wastewater treatment. As a passive aerated system, the only power needed is to transport the water to the top of the filter for distribution. Thus, understanding the role of filter aspect ratio on ammonia oxidation might save energy cost. In the present study, a pilot-scale comparison NTF system was conducted on two filters with different aspect ratios (height/diameter) and the same specific surface area. The nitrification efficiencies of these two filters under relatively low influent ammonia-nitrogen concentrations (1.0-4.0 mg NH4-N L-1) were investigated. Results obtained from the present study indicated that the constructional aspect ratio of NTF showed no significant effect on nitrification performance of NTFs. Additionally, the operational parameters showed similar effects on nitrification in NTFs with different aspect ratios. Our findings could provide important information for the construction design of future NTFs.

Comparison of the treatment performance of a high rate algal pond and a facultative waste stabilisation pond operating in rural South Australia.

South Australian community wastewater management schemes (CWMS) treat wastewater using waste stabilisation ponds before disposal or reuse. This study compared the performance of a facultative pond, 6,300 m2, 27.5 d theoretical hydraulic retention time (THRT), with a high rate algal pond (HRAP) operated at depths of 0.32, 0.43 and 0.55 m with THRT equivalent to 4.5, 6.4 and 9.1 d respectively. Both ponds received influents of identical quality, differing only in quantity, and were operated in similar climatic conditions. The depth of HRAP operation had only a minor influence on treatment performance. The study showed that the quality of the treated effluent from the HRAP was equivalent to that of the facultative pond, 5-day biochemical oxygen demand removal >89%, NH4-N removal 59.09-74.45%. Significantly, Escherichia coli log10 reduction values by the HRAP, 1.74-2.10, were equivalent to those of the facultative pond. Consequently, HRAPs could replace facultative ponds within CWMS while maintaining treated effluent quality. The benefit would be halving the surface area requirement from 4.2 m2 capita-1 for the facultative pond to between 2.0 and 2.3 m2 capita-1, depth dependent, for an HRAP, with significant attendant reductions in the capital costs for construction.

MS2 coliphage and E. coli UVB inactivation rates in optically clear water: dose, dose rate and temperature dependence.

Natural ultraviolet irradiance disinfection is known to play a significant role in both natural wastewater treatment systems and drinking water disinfection processes, while the influence of ultraviolet B (UVB) delivering method on sunlight disinfection outcome is still unclear. This study aims to determine the effects of environmentally relevant temperatures, UVB doses (J m-2) and dose rates (W m-2) on the inactivation and log reduction values (LRVs) of the F-RNA coliphage MS2 and Escherichia coli in optically clear water. E. coli and MS2 were separately incubated and irradiated at five different doses of UVB light that delivered using six UVB dose rates. The results of the study demonstrate that the UVB dose delivering method (combination of dose rate and exposure time) influences inactivation and LRVs of E. coli and MS2 at all UVB doses investigated (up to seven-fold difference). Two phases were identified within the UVB dose rate, UVB inactivation or LRV curves for both organisms; a UVB dose rate limited inactivation phase and a dose rate saturation inactivation phase. The results contribute to a better understanding of UVB disinfection in the environment and natural wastewater treatment systems, potentially improving the design and operation of high rate algal ponds.

Natural and surfactant modified zeolites: A review of their applications for water remediation with a focus on surfactant desorption and toxicity towards microorganisms.

The objective of this review is to highlight the need for further investigation of microbial toxicity caused by desorption of surfactant from Surfactant Modified Zeolite (SMZ). SMZ is a low cost, versatile permeable reactive media which has the potential to treat multiple classes of contaminants. With this combination of characteristics, SMZ has significant potential to enhance water and wastewater treatment processes. Surfactant desorption has been identified as a potential issue for the ongoing usability of SMZ. Few studies have investigated the toxicity of surfactants used in zeolite modification towards microorganisms and fewer have drawn linkages between surfactant desorption and surfactant toxicity. This review provides an overview of natural zeolite chemistry, characteristics and practical applications. The chemistry of commonly used surfactants is outlined, along with the kinetics that drive their adsorption to the zeolite surface. Methodologies to characterise this surfactant loading are also described. Applications of SMZ in water remediation are highlighted, giving focus to applications which deal with biological pollutants and where microorganisms play a role in the remediation process. Studies that have identified surfactant desorption from SMZ are outlined. Finally, the toxicity of a commonly used cationic surfactant towards microorganisms is discussed. This review highlights the potential for surfactant to desorb from the zeolite surface and the need for further research into the toxicity of this desorbed surfactant towards microorganisms, including pathogens and environmental microbes.

The toxicity of cationic surfactant HDTMA-Br, desorbed from surfactant modified zeolite, towards faecal indicator and environmental microorganisms.

Surfactant Modified Zeolite (SMZ) represents a versatile, cost-effective permeable reactive material, capable of treating multiple classes of contaminants. The potential for HDTMA-Br, a cationic surfactant commonly used to modify zeolite, to desorb from the zeolite surface has been identified as a potential issue for the ongoing use of SMZ in water remediation contexts. This paper investigates the toxicity of HDTMA-Br towards enteric virus surrogates, F-RNA bacteriophage MS2 and E. coli, Bacillus subtilis, and soil microflora. The concentration of surfactant desorbing from SMZ was quantified through a bioassay using E. coli. Results showed HDTMA-Br concentrations of ≥10-5M were toxic to MS2, ≥10-4M were toxic to E. coli and ≥10-6M were toxic to B. subtilis. No toxic relationship was established between HDTMA-Br and soil microflora. Desorption of ≥10-4M of HDTMA-Br was shown for the two SMZ samples under the mixing conditions used. Effects of this surfactant on total soil microflora were ambiguous since no toxic relationship could be established, however, HDTMA-Br, at concentrations desorbing from SMZ, were shown to impact the soil bacterium B. subtilis. Further research is required to determine the effect of this surfactant on microbial populations and species diversity in soils.

Reducing Risk of Salmonellosis through Egg Decontamination Processes.

Eggs have a high nutritional value and are an important ingredient in many food products. Worldwide foodborne illnesses, such as salmonellosis linked to the consumption of eggs and raw egg products, are a major public health concern. This review focuses on previous studies that have investigated the procedures for the production of microbiologically safe eggs. Studies exploring pasteurization and decontamination methods were investigated. Gamma irradiation, freeze drying, hot air, hot water, infra-red, atmospheric steam, microwave heating and radiofrequency heating are all different decontamination methods currently considered for the production of microbiologically safe eggs. However, each decontamination procedure has different effects on the properties and constituents of the egg. The pasteurization processes are the most widely used and best understood; however, they influence the coagulation, foaming and emulsifying properties of the egg. Future studies are needed to explore combinations of different decontamination methods to produce safe eggs without impacting the protein structure and usability. Currently, eggs which have undergone decontamination processes are primarily used in food prepared for vulnerable populations. However, the development of a decontamination method that does not affect egg properties and functionality could be used in food prepared for the general population to provide greater public health protection.

A Review of Temperature, pH, and Other Factors that Influence the Survival of Salmonella in Mayonnaise and Other Raw Egg Products.

Salmonellosis is one of the main causes of foodborne illnesses worldwide, with outbreaks predominately linked to contamination of eggs and raw egg products, such as mayonnaise. This review explores previous studies that have investigated Salmonella control mechanisms utilized in the production of raw egg mayonnaise and other food products. Apart from the use of pasteurized eggs, the main control mechanism identified is the pH of the raw egg products, which plays an important role in the consistency and stability while affecting the survival of Salmonella spp. However, currently there is no consensus regarding the critical pH limit for the control of Salmonella. The effectiveness of pH as a control mechanism is influenced by the type of acid used, with the effectiveness of lemon juice compared with vinegar highly debated. Additionally, Salmonella susceptibility to pH stresses may also be influenced by storage temperature (in some studies refrigeration temperatures protected Salmonella spp. from acidulants) and is further complicated by the development of Salmonella cross-tolerance-induced responses, pH homeostasis achieved by the cellular antiport and symport systems, and acid tolerance response (ATR). These mechanisms all provide Salmonella with an added advantage to ensure survival under various pH conditions. Other confounding factors include the fat content, and the addition of NaCl, garlic and plant essential oils (PEOs) from mint, cinnamon, cardamom and clove.

Higher Storage Temperature Causes Greater Salmonella enterica Serovar Typhimurium Internal Penetration of Artificially Contaminated, Commercially Available, Washed Free Range Eggs.

Foodborne salmonellosis is a major public health concern, with contaminated eggs identified as a significant source of infection. In Australia, the most prevalent cause of salmonellosis from eggs is Salmonella enterica subsp. enterica serovar Typhimurium. This study explored the effect of temperature after 1, 7, 14, 21, and 28 days of storage on commercially available washed free range eggs, artificially contaminated with Salmonella Typhimurium on the external surface. At each time point, the external surface of the egg, the crushed eggshell, and the internal egg yolk and albumen were analyzed for Salmonella. After 28 days of storage, 25% of eggs stored at 4°C, 50% of eggs stored at 14°C, and 100% of eggs stored at 23 and 35°C were internally contaminated with Salmonella. After 1 day of storage, more than 50% of all eggs had Salmonella present in the crushed shell after the external surface had been disinfected with ethanol. This is the first study to demonstrate that refrigeration reduced the potential for Salmonella Typhimurium to penetrate the eggshell membrane and internally contaminate table eggs commercially available in Australia. It also suggests that the processes of cracking eggs may be a source of cross-contamination within the kitchen.

Impact of exogenous organic carbon on the removal of chemicals of concern in the high rate nitrifying trickling filters.

The application of fixed bed high rate nitrifying trickling filters (NTFs) for the removal of track organic chemicals of concern (CoC) is less well known than their application to nutrient removal in water treatment. Particularly, the effect of exogenous organic carbon substrate (sucrose) loading on the performance of NTFs is not well understood. A laboratory-scale NTF system was operated in recirculation mode, with the objective of removing ammonia and CoC simultaneously. The efficiency of a high rate NTF for removal both of low concentration of ammonia (5 mg NH4-N L(-1)) and different concentrations of CoC in the presence of an exogenous organic carbon substrate (30 mg total organic carbon (TOC) L(-1)) was investigated. In the presence of exogenous organic carbon, the results demonstrated that the high rate NTF was able to successfully remove most of the CoCs investigated, with the removal ranging from 20.2% to 87.54%. High removal efficiencies were observed for acetaminophen (87.54%), bisphenol A (86.60%), trimethoprim (86.24%) and 17α-ethynylestradiol (80.60%). It was followed by the medium removal efficiency for N, N-diethyl-m-toluamide (61.31%) and atrazine (56.90%). In contrast, the removal of caffeine (28.43%) and benzotriazole (20.20%) was poorer in the presence of exogenous organic carbon. The removal efficiency for CoC was also compared with the results obtained in our previous study in the absence of exogenous organic carbon. The results showed that the addition of exogenous organic carbon was able to improve the removal of some of the CoC. Significant TOC percentage removals (45.68%-84.43%) and ammonia removal rate (mean value of 0.44 mg NH4-N L(-1) h(-1)) were also achieved in this study. The findings from this study provide valuable information for optimising the efficiency of high rate NTF for the removal of ammonia, CoC and TOC.