Edmond O'Reilly

Efficacy of using harmless Bacillus endospores to estimate the inactivation of Cryptosporidium parvum oocysts in water.

Abstract: The need to use complex in vitro cell culture, expensive equipment, and highly-trained technicians that are available only to specialist laboratories has significantly limited studies assessing the potential of pulsed UV light (PUV) to inactivate the waterborne parasite Cryptosporidium parvum in drinking water. This constitutes the first study to report on the use of different non-pathogenic Bacillus endospores as potential surrogate organisms to indicate the PUV inactivation performance of a C. parvum oocyst suspended in water. Findings showed that PUV effectively inactivated approximately 5 log10 CFU/ml Bacillus megaterium and Bacillus pumilus endospores suspended in water at a UV dose of 9.72 μJ/cm2 that also inactivated statistically similar levels of C. parvum oocysts (P < 0.05), as determined by combined in vitro HCT-8 cell culture and quantitative PCR. Specifically, this study demonstrated that B. megaterium exhibited greater or similar PUV-inactivation kinetic data compared to that of similarly treated C. parvum over the UV dose range 6.4 to 12.9 μJ/cm2. Therefore, the former may be used as an indicator organism for safely investigating the PUV-inactivation performance of this chlorine-resistant, waterborne parasite at the waste-water treatment plant level. Findings presented will impact positively on future water quality studies and on public health.

Pumped flow biofilm reactors (PFBR) for treating municipal wastewater.

A novel laboratory bench-scale sequencing batch biofilm reactor (SBBR) system was developed for the treatment of synthetic domestic strength wastewater, comprising two side-by-side 18 l reactor tanks, each containing a plastic biofilm media module. Aerobic and anoxic conditions in the biofilms were effected by intermittent alternate pumping of wastewater between the two reactors. With a media surface area loading rate of 4.2 g chemical oxygen demand (COD)/m2.d, the average influent COD, total nitrogen (TN) and ammonium-nitrogen (NH4-N) concentrations of 1021 mg/l, 97 mg/l and 54 mg/l, respectively, reduced to average effluent concentrations of 72 mg COD/l, 17.8 mg TN/l, and 5.5 mg NH4-N /l. Using a similar alternating biofilm exposure arrangement, a 16 person equivalent pilot (PE) plant was constructed at a local village treatment works to remove organic carbon from highly variable settled municipal wastewater and comprised two reactors, one positioned above the other, each containing a module of cross-flow plastic media with a surface area of 100 m2. Two different pumping sequences (PS) in the aerobic phase were examined where the average influent COD concentrations were 220 and 237 mg/l for PS1 and PS2, respectively, and the final average effluent COD was consistently less than 125 mg/l--the European Urban Wastewater Treatment Directive limit--with the best performance occurring in PS1. Nitrification was evident during both PS1 and PS2 studies. A 300 PE package treatment plant was designed based on the bench-scale and pilot-scale studies, located at a local wastewater treatment works and treated municipal influent with average COD, suspended solids (SS) and TN concentrations of 295, 183 and 15 mg/l, respectively resulting in average effluent concentrations of 67 mg COD/l, 17 mg SS/l and 9 mg TN/l. The SBBR systems performed well, and were simple to construct and operate.

Synthetic dairy wash-water treatment by using an alternating pumped sequencing batch biofilm reactor

The performance of an alternating pumped sequencing batch biofilm reactor process in synthetic diary wash-water treatment was studied. The system comprises two reactors with two identical plastic biofilm modules. Two centrifugal pumps, one connected to each reactor, alternately move the water from one reactor to the other one, resulting in aeration. At three loading rates (336, 501 and 1080 g COD/(m³ d)), total COD and total nitrogen were removed by 91-94% and 46-80%, respectively. Nitrogen was removed from wastewater by denitrification in the anoxic phase and Simultaneous Nitrification and Denitrification (SND) in the aerobic phase.

Treatment of dairy soiled washwater using a woodchip filter

Introduction Soiled water is produced on dairy farms through the washing-down of milking parlours and holding areas and contains nutrients and other constituents that pose a potential threat to water quality if not managed correctly. In Ireland, soiled water is generally applied to land, but the risk of nutrient loss to surface and ground waters from land application has attracted increased attention and legislation in the form of the EU Nitrates Directive and Water Framework Directive. Treatment and re-use of soiled water may negate some of these risks. This study examines the potential of woodchip filters to treat soiled water.