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Long-term performance evaluation of EBPR process in tropical climate: start-up, process stability, and the effect of operational pH and influent C:P ratio

Ong YH, Chua AS, Lee BP, Ngoh GC

Water Sci Technol, 2013;67(2):340-6.
PMID: 23168633 DOI: 10.2166/wst.2012.552

To date, little information is known about the operation of the enhanced biological phosphorus removal (EBPR) process in tropical climates. Along with the global concerns on nutrient pollution and the increasing array of local regulatory requirements, the applicability and compliance accountability of the EBPR process for sewage treatment in tropical climates is being evaluated. A sequencing batch reactor (SBR) inoculated with seed sludge from a conventional activated sludge (CAS) process was successfully acclimatized to EBPR conditions at 28 °C after 13 days' operation. Enrichment of Candidatus Accumulibacter phosphatis in the SBR was confirmed through fluorescence in situ hybridization (FISH). The effects of operational pH and influent C:P ratio on EBPR were then investigated. At pH 7 or pH 8, phosphorus removal rates of the EBPR processes were relatively higher when operated at C:P ratio of 3 than C:P ratio of 10, with 0.019-0.020 and 0.011-0.012 g-P/g-MLVSS•day respectively. One-year operation of the 28 °C EBPR process at C:P ratio of 3 and pH 8 demonstrated stable phosphorus removal rate of 0.020 ± 0.003 g-P/g-MLVSS•day, corresponding to effluent with phosphorus concentration <0.5 mg/L. This study provides the first evidence on good EBPR activity at relatively high temperature, indicating its applicability in a tropical climate.
An observation on sludge granulation in an enhanced biological phosphorus removal process

Ong YH, Chua AS, Lee BP, Ngoh GC, Hashim MA

Water Environ Res, 2012 Jan;84(1):3-8.
PMID: 22368821

A sequencing batch reactor (SBR) seeded with flocculated sludge and fed with synthetic wastewater was operated for an enhanced biological phosphorus removal (EBPR) process. Eight weeks after reactor startup, sludge granules were observed. The granules had a diameter of 0.5 to 3.0 mm and were brownish in color and spherical or ellipsoidal in shape. No significant change was observed in sludge granule size when operational pH was changed from 7 to 8. The 208-day continuous operation of the SBR showed that sludge granules were stably maintained with a sludge volume index (SVI) between 30 to 55 mL/g while securing a removal efficiency of 83% for carbon and 97% for phosphorus. Fluorescent in situ hybridization (FISH) confirmed the enrichment of polyphosphate accumulating organisms (PAOs) in the SBR. The observations of sludge granulation in this study encourage further studies in the development of granules-based EBPR process.
Robust dengue virus infection in bat cells and limited innate immune responses coupled with positive serology from bats in IndoMalaya and Australasia

Irving AT, Rozario P, Kong PS, Luko K, Gorman JJ, Hastie ML, et al.

Cell Mol Life Sci, 2020 Apr;77(8):1607-1622.
PMID: 31352533 DOI: 10.1007/s00018-019-03242-x

Natural reservoir hosts can sustain infection of pathogens without succumbing to overt disease. Multiple bat species host a plethora of viruses, pathogenic to other mammals, without clinical symptoms. Here, we detail infection of bat primary cells, immune cells, and cell lines with Dengue virus. While antibodies and viral RNA were previously detected in wild bats, their ability to sustain infection is not conclusive. Old-world fruitbat cells can be infected, producing high titres of virus with limited cellular responses. In addition, there is minimal interferon (IFN) response in cells infected with MOIs leading to dengue production. The ability to support in vitro replication/production raises the possibility of bats as a transient host in the life cycle of dengue or similar flaviviruses. New antibody serology evidence from Asia/Pacific highlights the previous exposure and raises awareness that bats may be involved in flavivirus dynamics and infection of other hosts.
Meta-analysis: Prevalence and impact of alcohol abstinence in alcohol-associated cirrhosis

Lim WH, Tay P, Ng CH, Tan DJH, Ong C, Koh JH, et al.

Aliment Pharmacol Ther, 2024 Mar;59(6):730-741.
PMID: 38303565 DOI: 10.1111/apt.17888

BACKGROUND: Although alcohol abstinence may be an effective intervention for alcohol-associated cirrhosis, its association with prognosis has not been systematically assessed or quantified.
AIMS: To determine the prevalence of alcohol abstinence, factors associated with alcohol abstinence and the impact of abstinence on morbidity and overall survival in people with alcohol-associated cirrhosis.
METHODS: We searched Medline and Embase from inception to 15 April 2023 for prospective and retrospective cohort studies describing alcohol abstinence in people with known alcohol-associated cirrhosis. Meta-analysis of proportions for pooled estimates was performed. The method of inverse variance, employing a random-effects model, was used to pool the hazard ratio (HR) comparing outcomes of abstinent against non-abstinent individuals with alcohol-associated cirrhosis.
RESULTS: We included 19 studies involving 18,833 people with alcohol-associated cirrhosis. The prevalence of alcohol abstinence was 53.8% (CI: 44.6%-62.7%). Over a mean follow-up duration of 48.6 months, individuals who continued to consume alcohol had significantly lower overall survival compared to those who were abstinent (HR: 0.611, 95% CI: 0.506-0.738). These findings remained consistent in sensitivity/subgroup analysis for the presence of decompensation, study design and studies that assessed abstinence throughout follow-up. Alcohol abstinence was associated with a significantly lower risk of hepatic decompensation (HR: 0.612, 95% CI: 0.473-0.792).
CONCLUSIONS: Alcohol abstinence is associated with substantial improvement in overall survival in alcohol-associated cirrhosis. However, only half of the individuals with known alcohol-associated cirrhosis are abstinent.