Microbiological characterisation and impact of suspended solids on pathogen removal from wastewaters in dairy processing factories (original) (raw)
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REMOVAL OF PATHOGENS FROM DAIRY WASTEWATER BY UV TREATMENT
Proceedings of 24th edition - International Conference on Hydraulics and Pneumatics – HERVEX, 2018
Nutrient-rich wastewater has become a valuable resource for farmers, but if used untreated, the wastewater can pose serious risks for human health. There is potential for wastewater reuse in Romanian agriculture, but different wastewater treatment for agricultural reuse is only tested experimentally. Wastewater samples collected from the lagoon of a cow farm in Romania were tested to determine the microbiological load, expressed as efficiency removal of pathogens at UV treatment with germicidal lamps. Duration of treatment were of 1, 5, 10, 15, 20 and 30 minutes, and highest efficiency was of 87%, showing that UV treatment can be used at large scale for the disinfection of dairy wastewater before its reuse as irrigation water.
Reduction of Pathogen Indicator Organisms in Dairy Wastewater Using an Ecological Treatment System
Journal of Environment Quality, 2008
Ecological treatment systems can provide a sustainable, plantbased alternative to traditional wastewater treatment. One factor essential to the success of these systems is ensuring their ability to reduce coliform concentrations in wastewater. Wastewater is the primary source of fecal contamination in aquatic ecosystems, containing total and fecal coliforms on the order of 10 8 -10 10 and 10 7 -10 9 CFU L −1 , respectively. Th is study assessed the ability of an ecological treatment system to reduce concentrations of total coliforms and Escherichia coli from dairy wastewater. Low strength wastewater was pumped into the system during July of 2005 and high strength in September 2005. Wastewater passes through a series of anaerobic, aerobic, and clarifi er reactors and wetland cells before exiting the system. Regardless of wastewater strength, average total coliform and E. coli concentrations were consistently reduced by at least 99% from infl uent to effl uent, with the majority of the reduction (76%) occurring in the fi rst two reactors. Relationships between internal concentrations of solids and coliforms indicated that increased reduction of solids may further reduce coliform concentrations. Although U.S. Environmental Protection Agency discharge requirements for E. coli were not always met, the substantial reductions achieved indicate that ecological treatment systems have the potential to successfully reduce coliforms in wastewater to meet discharge limits. Th e results from this study will be used to guide design and management of future ecological treatment systems, so that larger and more consistent coliform reductions can be achieved.
Characterization of Chemical and Bacterial Compositions of Dairy Wastewaters
Dairy, 2021
The dairy industry produces large amounts of wastewater, including white and cleaning wastewater originating principally from rinsing and cleaning-in-place procedures. Their valorization into process water and non-fat milk solids, in the case of white wastewater, or the renewal of cleaning solutions could be achieved using pressure-driven membrane processes. However, it is crucial to determine the intrinsic characteristics of wastewaters, such as proximate composition and bacterial composition, to optimize their potential for valorization. Consequently, white and cleaning wastewaters were sampled from industrial-scale pasteurizers located in two different Canadian dairy processing plants. Bacterial profiles of dairy wastewaters were compared to those of tap waters, pasteurized skim milk and unused cleaning solutions. The results showed that the physicochemical characteristics as well as non-fat milk solids contents differed drastically between the two dairy plants due to different p...
Evaluation of sanitation procedures for use in dairies
VTT PUBLICATIONS, 2002
The research work for project P96049 in the second NORDFOOD programme was carried out at the Nordic research institutes VTT Biotechnology, MATFORSK and SIK as well as at the universities in Helsinki and Reykjavik from April 1997 to January 2000. The companies involved in the project were the dairies Valio Ltd. from Finland, Arla from Sweden and TINE from Norway as well as the technochemical company Suomen Unilever Oy DiverseyLever from Finland. Dr Gun Wirtanen, VTT Biotechnology, coordinated the project. The senior advisors at Nordic Industrial Fund involved in the project were Maija Uusisuo and Oddur Gunnarsson. The experiments were focused on monitoring methods in sanitation of open and closed systems e.g. fogging, ozonation, footbath hygiene, cleaning of cheese moulds and yoghurt pasteurizers, development of testing procedures for measuring disinfectant efficacy, microbial resistance phenomena against disinfectants, life-cycle assessment (LCA) and an evaluation procedure for the functionality of the cleaning procedures. New procedures in hygiene have been implemented in dairies, based on the results. The findings can be summarized as follows: • The main task of the research conducted in Sweden was to develop and evaluate practical methods for the measure of cleaning and disinfection efficiency. These methods are suitable for equipment surfaces used for production of various dairy products. The analysing methods, washing out and triphenyltetrazolium chloride (TTC) agar, worked well in testing the cleanability of plastic cheese moulds. As part of this study a 5-step method how to evaluate cleaning and disinfection agents was prepared at Arla Foods. • Bacillus cereus is an important target organism when disinfecting equipment for production of consumer milk in Nordic dairies. The total number of remaining Bacillus spores on solid surfaces is a useful indicator for measuring cleaning and disinfection efficiency. Improved methods for detection of surface-adhered spores can be based on fluorescent dyes, 9
Food Protection Trends
Treatment of agricultural water aids in the prevention of foodborne disease outbreaks linked to contaminated fresh produce. UV light is a suitable alternative for treating drinking water but is not always effective for surface irrigation water due to interference caused by turbidity and high microbial loads. The effectiveness of UV treatment for reducing Escherichia coli and Salmonella in surface water used in agriculture was evaluated. Six pond water samples were collected on each of 16 sampling dates over a 3-year period. On each corresponding testing date, three samples were inoculated with Salmonella enterica serovars Hartford, Montevideo, and Gaminara and the other three samples were inoculated with E. coli ATCC 25922, targeting a concentration of 7 log CFU/mL. Inoculated water was UV treated with a commercially available juice processing UV device at a constant UV dose of 14.2 mJ/cm2 and a turbulent flow regime. The effects of date, initial bacterial counts, and water pH and t...
Journal of Membrane Science, 2010
The efficacy of different cleaners and sanitisers for removing or killing Klebsiella oxytoca in biofilms on ultrafiltration (UF) membranes from the dairy industry was investigated. K. oxytoca B006 was grown individually and combined with another K. oxytoca strain, TR002, on polyethersulfone (PES) UF membranes in 5% whey medium in CBR 90 biofilm reactors. Both strains were previously isolated from New Zealand dairy plants. Three enzymatic cleaners were compared with sodium hypochlorite (pH 10.8-11) at 200 ppm free available chlorine (FAC) commonly used for cleaning-in-place (CIP) of UF membranes in the dairy industry. In addition, 4 sanitisers were used to treat the membranes after a CIP wash regime. The efficacy in reducing culturable bacteria in biofilms was measured using pour plate counting on standard plate count agar. QuatroZyme ® , which is composed of mixed enzymes, performed slightly better than the other cleaners. The treatments with all the sanitisers improved cleaning. MIOX ® EW anolyte (pH 6.8) (120 ppm) was the most effective sanitiser compared to the control CIP. However, PES UF membranes are known to be sensitive to oxidants at low pH and therefore the damage to these membranes by MIOX ® EW anolyte needs to be determined.
African Journal of Microbiology Research, 2020
This study aims to assess the impact of the use of treated wastewater (without chlorination) in farming and dairy cattle breeding. Milk samples were collected from a farm in northeastern Algeria. The treated wastewater from the treatment plant is used on this farm for different activities. The results obtained show that the average contamination of milks with total flora is 3.7.10 5 CFU /ml. Fecal coliforms are present at an average value of 1.5.10 3 CFU/ml. All of the samples (100%) were positive for the count of fecal enterococci with an average value of 2.5.10 CFU/ml. Fungal flora was present with an average value of 1.36,10 3 CFU/ml. Escherichia coli was isolated in 100% of the samples with high resistance rates for beta-lactam antibiotics. The results obtained for the search for pathogens belonging to the genus Staphylococcus show that 64% of the isolates were coagulase-negative Staphylococcus and 36% of the isolates were coagulase-positive. The study of Staphylococcus susceptibility/resistance to antibiotics revealed high frequencies of resistance, especially to beta-lactam antibiotics and macrolides. The bacteria tested show a majority resistance for Penicillin and Oxacillin (100%). These results reflect the microbiological risk that the consumption and marketing of this milk represents for the health of consumers and the need to implement preventive measures.
Comparison of advanced disinfecting methods for municipal wastewater reuse in agriculture
Water Science and Technology
The experimental investigation carried out jointly by Italian and Israeli teams within a 3-year research project funded by the European Commission on alternative disinfection methods for reusing municipal wastewater in agriculture is described. Disinfection effectiveness of UV rays, ozone (O3) and peracetic acid (PAA) at pilot scale and hydrogen peroxide (H2O2) plus silver (Ag+) or copper (Cu+2) at laboratory scale was compared for tertiary municipal effluents. Pilot plant results indicated that the well known California limit (2 CFU/100ml of Total Coliforms) was effectively met with reasonable UV doses of 100–160 mWs/cm2 or with exceedingly high PAA dosage (400 PPM); the related WHO microbial guideline (1,000 CFU/100 ml of Fecal Coliforms) was easily met with all three disinfectants (UV, PAA, O3); maximum log-inactivation values were ≥5 for UV and PAA and ≤4 for O3. Laboratory results with tertiary effluents demonstrated that Ag+ was able to inactivate target bacteria (E. coli-B, E...
Journal of Food Protection, 2004
A laboratory scale system, partially reproducing dairy plant conditions, was developed to quantify the effectiveness of chlorine and alternative sanitizers in reducing the number of viable bacteria attached to stainless steel surfaces. Stainless steel tubes fouled in a continuous flow reactor were exposed to a standard clean-in-place regime (water rinse, 1% sodium hydroxide at 70°C for 10 min, water rinse, 0.8% nitric acid at 70°C for 10 min, water rinse) followed by exposure to either chlorine (200 ppm) or combinations of nisin (500 ppm), lauricidin (100 ppm), and the lactoperoxidase system (LPS) (200 ppm) for 10 min or 2, 4, 8, 18, or 24 h. There was significant variation in the effectiveness of the alkaline-acid wash steps in reducing cell numbers (log reduction between 0 and 2). Following a 10-min treatment, none of the sanitizers significantly reduced the number of attached cells. Two hours of exposure to chlorine, nisin + the LPS, or lauricidin + the LPS achieved 2.8, 2.2, and...
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Electrochemically activated water (ECAW), also known as electrolyzed water, and ozonized water are typically effective in inactivating bacteria, but their generation typically uses high current and voltage. A few simpler antimicrobial technologies that are also based on the application of a mild electrical current have been recently marketed to food retail and service customers claiming to have sanitizing properties for controlling bacteria. The objective of this study was to determine the sanitizing effect of some of these commercial technologies on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica and compare them with sterile water, generated ECAWgenerated with a pilot size electrolyzing unit, and salt solutions sprayed using commercial device sprays. A concentration of 100 mg/L ECAW had sanitizing effects of at least 5 log CFU/mL reductions on liquid culture and more than 4 log CFU/coupon reductions for E. coli O157:H7, L. monocytogenes and Salmonella dried on stainless steel surface, respectively. No bacterial cells were detected by direct plate counting post-ECAW treatment. In contrast, the treatment of liquid cultures with any of the commercial technologies tested resulted in non-significant bacterial cell reductions greater than 0.5 log CFU/mL. Similarly, when cells had been dried on metal surfaces and treated with any of the water generated with those technologies, no reductions were observed. When the manufacturer’s instructions were followed, the reduction of cells on surface was largely due to the physical removal by cloth-wiping after water fraction application. These results indicate that treatment with any of these portable technologies had no noticeable antimicrobial activity. These results would be helpful for guiding consumers when choosing a right sanitization to ensure food safety.