Application of aerobic kenaf granules for biological nutrient removal in a full-scale continuous flow activated sludge system.

Aerobic granular sludge (AGS) is a biofilm technology that offers more treatment capacity in comparison to activated sludge. The integration of AGS into existing continuous-flow activated sludge systems is of great interest as process intensification can be achieved without the use of plastic-based biofilm carriers. Such integration should allow good separation of granules/flocs and ideally with minor retrofitting, making it an ongoing challenge. This study utilized an all-organic media carrier made of porous kenaf plant stalks with high surface areas to facilitate biofilm attachment and granule development. A 5-stage Bardenpho plant was upgraded with the addition of kenaf media and a rotary drum screen to retain the larger particles from the secondary clarifier underflow whereas flocs were selectively wasted. Startup took 5 months with a sludge volume index (SVI) reduction from >200 to 50 mL g-1. Most of the kenaf granules fell in the size range of 600-1400 µm and had a clear biofilm layer. The wet biomass density, SVI30, and SVI30/SVI5 of the kenaf granules were 1035 g L-1, 30.6 mL g-1, and 1.0, respectively, which met the standards of aerobic granules. Improved stability of biological phosphorus removal performance enabled a 25% reduction in sodium aluminate usage. Microbial activities of kenaf granules were compared with aerobic granules, showing comparable N and P removal rates and presence of ammonium-oxidizing bacteria and polyphosphate-accumulating organisms in the outer 50-60 µm layer of the granule. This work is the first viable example for integrating fully organic biofilm particles in existing continuous-flow systems.

Clinical Manifestations, Management, and Outcomes of Osteitis/Osteomyelitis Caused by Mycobacterium bovis Bacillus Calmette-Guérin in Children: Comparison by Site(s) of Affected Bones.

OBJECTIVE: To evaluate the clinical manifestations, management, and outcomes of Mycobacterium bovis Bacillus Calmette-Guérin (BCG) osteitis/osteomyelitis. STUDY DESIGN: We reviewed 71 cases of BCG osteitis/osteomyelitis registered in Taiwan's vaccine injury compensation program (VICP) in 1998-2014. Demographic, clinical, laboratory, treatment, and outcome data were compared according to site(s) of infection. RESULTS: Involvement of a long bone of the lower extremity was present in 36.6% of the children, followed by foot bone (23.9%), rib or sternum (15.5%), upper extremity long bone (9.9%), hand bone (7%), multiple bones (4.2%), and vertebrae (2.8%). Children with lower extremity long bone involvement had a longer interval from receipt of BCG vaccine to presentation (median, 16.0 months; P = .02), and those with foot bone infection had higher rates of swelling (94.1%; P = .02) and local tenderness (76.5%; P = .004). Surgical intervention was performed in 70 children, with no significant difference in the number of procedures by site (median, 1.0 procedure per patient). Among the 70 children who received antimicrobial therapy, those with vertebral and multifocal infections had a longer duration of treatment (P < .001) and/or second-line antituberculosis medications (P = .002). Three children with vertebral and multifocal infections had major sequelae with kyphosis or leg length discrepancy. Outcomes were good for children with involvement of the ribs, sternum, and peripheral bones without multifocal involvement. The average time for functional recovery was 6.2 ± 3.9 months. CONCLUSION: Children with BCG osteitis/osteomyelitis in different bones had distinct presentations and outcomes. Pediatricians should consider BCG bone infection in young vaccinated children with insidious onset of signs and symptoms, and consider affected site(s) in the management plan.

Nucleic Acid Photolysis by UV254 and the Impact of Virus Encapsidation.

Determining the influence of higher order structure on UVC photolysis will help inform predictions of nucleic acid fate and microorganism inactivation. We measured the direct UV254 photolysis kinetics of four model viral genomes composed of single-stranded and double-stranded RNA (ssRNA and dsRNA, respectively), as well as single-stranded and double-stranded DNA (ssDNA and dsDNA, respectively), in ultrapure water, in phosphate buffered saline (PBS), and encapsidated in their native virus particles. The photolysis rate constants of naked nucleic acids measured by qPCR (RT-qPCR for RNA) and normalized by the number of bases measured in a particular sequence exhibited the following trend: ssDNA > ssRNA ≈ dsDNA > dsRNA. In PBS, naked ssRNA bases reacted, on average, 24× faster than the dsRNA bases, whereas naked ssDNA bases reacted 4.3× faster than dsDNA bases. Endogenous indirect photolysis involving 1O2 and ·OH was ruled out as a major contributing factor in the reactions. A comparison of our measured rate constants with rate constants reported in the literature shows a general agreement among the nucleic acid UV254 direct photolysis kinetics. Our results underscore the high resistance of dsRNA to UVC photolysis and demonstrate the role that nucleic acid structure and solution chemistry play in photoreactivity.

Reactivity of Enveloped Virus Genome, Proteins, and Lipids with Free Chlorine and UV254.

The survivability of viruses in natural and engineered systems impacts public health. Inactivation mechanisms in the environment have been described for nonenveloped viruses, but it remains unclear how the membrane layer of enveloped viruses influences inactivation. We applied molecular tools and high-resolution mass spectrometry to measure reactions in the genome, proteins, and lipids of enveloped Pseudomonas phage Phi6 during inactivation by free chlorine and UV254. Free chlorine readily penetrated the lipid membrane to react with proteins in the nucleocapsid and polymerase complex. The most reactive Phi6 peptides were approximately 150 times more reactive with free chlorine than the most reactive peptides reported in nonenveloped coliphage MS2. The inactivation kinetics of Phi6 by UV254 was comparable with those of nonenveloped adenovirus and coliphage MS2 and were driven by UV254 reactions with viral genomes. Our research identifies molecular features of an enveloped virus that are susceptible to chemical oxidants or UV radiation. Finally, the framework developed in the manuscript for studying molecular reactivities of Phi6 can be adopted to investigate enveloped virus survivability under various environmental conditions.

Degradation of Extracellular Antibiotic Resistance Genes with UV254 Treatment.

Disinfected wastewater effluent contains a complex mixture of biomolecules including DNA. If intact genes conveying antibiotic resistance survive the disinfection process, environmental bacteria may take them up. We treated plasmid pWH1266, which contains ampicillin resistance gene blaTEM-1 and tetracycline resistance gene tetA, with UV254 doses up to 430 mJ/cm2 and studied the ability of those genes to be acquired by Acinetobacter baylyi. The plasmids required approximately 20-25 mJ/cm2 per log10 loss of transformation efficiency. We monitored plasmid DNA degradation using gel electrophoresis and qPCR with both short amplicons (∼200 bps, representative of ARG amplicon lengths commonly used for environmental monitoring) and long amplicons (800-1200 bps, designed to cover the entire resistance genes). The rate of transformability loss due to UV254 treatment was approximately 20× and 2× larger than the rate of gene degradation measured with the short and long amplicons qPCR, respectively. When extrapolated to account for the length of the entire pWH1266 plasmid, the qPCR rate constants were 2-7× larger than the rate constants measured with transformation assays. Gel electrophoresis results confirmed that DNA cleavage was not a major inactivating mechanism. Overall, our results demonstrate that qPCR conservatively measures the potential for a gene to be transformed by environmental bacteria following UV254 treatment.