Copolymers based on aliphatic diamines of various methylene chain lengths and guanidine hydrochloride were prepared by polycondensation in the melt. Antibacterial activity of water-soluble copolymers based on guanidine against conditionally pathogenic microorganisms Escherichia coli and Bacillus cereus was evaluated using diffusion in agar. A relationship was found between the ratio of the number of hydrophobic methylene groups to the number of ionized guanidines and the antibacterial activity of the copolymers. Several samples showed high antimicrobial activity as compared with polyhexamethyleneguanidine hydrochloride (PHMGHC), which is widely used as a medical disinfectant.

This work evaluated the feasibility of a photo-Fenton-like process using persulfate (PS) and ferrous iron (Fe) under simulated solar radiation for degrading the herbicide atrazine (ATZ, 6-Chloro-N-ethyl-N'-isopropyl-1,3,5-triazine-2,4-diamine) and inactivating E. coli. Milli Q water, lake water, and diluted wastewater effluents were spiked both simultaneously and separately with ATZ (4 mg/L) and E. coli (10 CFU/mL), and exposed to treatment. A method for determining the average irradiance throughout the water media in the UV(A+B) range of the Xe lamp emission was developed for bench-scale experiments. These values were used to calculate the UV(A+B) fluences and the solar UV(A+B) energy doses per unit of volume (Q, kJ/L). The obtained kinetic data were presented versus energy dose. Treatment of lake water at near-neutral pH was ineffective via the photo-Fenton-like process, attaining only 20% ATZ removal and 1-log reduction of E. coli. In Milli Q water and wastewater, the complete degradation of ATZ in the absence of bacteria was observed at an average energy dose of 1.5 kJ/L (60 min), while in the presence of cells the degradation efficiency was ∼60%. When ATZ was present, E. coli inactivation was also affected in Milli Q water, with 1.4-log reduction (93%) at a dose of 1.6 kJ/L (60 min), whereas in wastewater complete inactivation was achieved at a lower dose of 1.3 kJ/L (45 min). The energy requirements on a Q basis for simultaneous 90% ATZ removal and 99.99% E. coli inactivation in Milli Q water and wastewater were shown to be less than 10 kJ/L. This suggests the solar/PS/Fe system is promising for simultaneous treatment and disinfection of wastewater effluents.

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The combination of high-frequency ultrasound (HFUS) and UV represents a new approach to disinfecting surfaces. This study aimed to examine the inactivation efficiency of HFUS (1.7 MHz) and monochromatic UV radiation of KrCl excilamp (222 nm) in a single and a sequential mode against Bacillus cereus cells and spores added to glass surfaces. When treated by UV only, cells at populations of 10 3 , 10 4 , and 10 5 colony-forming units (CFU)/cm 2 showed 100% disinfection at high doses up to 1760 mJ/cm 2 . Spores at 10 4 CFU/cm 2 were completely inactivated at a dose of 1170 mJ/cm 2 . Treatment with aqueous aerosol (produced by HFUS) reduced cell counts by 100% within a 40-min exposure, whereas it was ineffective in inactivating spores under these conditions. In a sequential mode, the contaminated surface was pretreated with the sonicated aqueous aerosol and subsequently irradiated with the excilamp. It was found that HFUS exposure times and UV doses for complete inactivation decreased by a factor of 2 and 6-7, respectively, compared to sole HFUS or UV. A portable apparatus for surface disinfection was designed. The combined HFUS/UV method may be a promising technique for rapid disinfection of microbially contaminated surfaces.

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