Dynamic impact of cellulose and readily biodegradable substrate on oxygen transfer efficiency in sequencing batch reactors.

Aeration is a major contributor to the high energy demand in municipal wastewater treatment plants. Thus, it is important to understand the dynamic impact of wastewater characteristics on oxygen transfer efficiency to develop suitable control strategies for minimizing energy consumption since aeration efficiency is influenced by the biodegradation of pollutants in the influent. The real-time impact of acetate as a readily biodegradable substrate and cellulose as a slowly biodegradable substrate were studied at different operational conditions. Cellulose in the influent wastewater can be removed efficiently using primary treatment technologies, such as the rotating belt filter (RBF). At an ambient DO of 2 mg l-1 and air flow of 1.02 m3h-1 (0.6 SCFM), the α-factor was more sensitive to readily biodegradable substrates than to cellulose. On average, α-factor decreased by 48% and 19% due to the addition of acetate and cellulose, respectively. At a DO of 4 mg l-1 and air flow of 1.7 m3h-1 (1 SCFM), α-factor remained constant irrespective of cellulose and acetate concentrations. Without active biomass, α-factor decreased by 47% and 43% at a DO of 2 mg l-1 (air flow of 1.02 m3h-1) and high DO of 5 mg l-1 (air flow of 1.7 m3h-1), respectively. An inverse correlation between α-factor and sCOD was defined and incorporated into a dynamic model to estimate the real-time airflow rates associated with the improvement of the oxygen transfer efficiency due to biodegradation. Finally, the RBF operated with a 158-µm mesh selectively removed cellulose, thus reducing air requirements, and energy by 25%.

Fate of cellulose in primary and secondary treatment at municipal water resource recovery facilities.

Cellulose from toilet paper is a significant fraction of particulate organics, which is recoverable. For the first time, comprehensive mapping and tracking the fate of cellulose across various unit processes at full-scale in two water resource recovery facilities located in North America and Europe was undertaken. The influent cellulose content accounted for approximately one-third of the total suspended solids (TSS). Although about 80% of the raw wastewater cellulose was removed in primary treatment, the type of primary treatment process (rotating belt filter [RBF] vs. primary clarification [PC]) had a significant impact on cellulose capture and diversion. The high cellulose content of the RBF sludge accounting for 35% of the TSS facilitates cellulose recovery. For the North American plant, with a conventional activated sludge process (SRT of 6-7 days, preceded by PC), cellulose biodegradation efficiencies of 70%-90% of the PC effluent were observed in summer and winter. For the European plant, with a modified University of Cape Town process (SRT of 14 days, without primary treatment in train 2, or preceded by RBF in train 1), comparable cellulose biodegradation efficiencies were also observed. Results from laboratory SBRs indicated that cellulose biodegradation efficiency at room temperature was 86% of the influent cellulose. PRACTITIONER POINTS: Cellulose fate was tracked across two different WWTPs in two different geographies. Cellulose in the influent wastewater accounted for 1/3 of the total suspended solids. Primary treatments were able to capture more than 80% of the influent cellulose. Cellulose was biodegraded in secondary treatment, resulting an effluent of 2-3 mg/L.

Incidental findings of Cysticercus tenuicollis metacestodes in five oryx species

Objective: To determine the prevalence of Cysticercus tenuicollis (C. tenuicollis) metacestodes in five oryx species kept in Al Ain Zoo animal collection. Methods: This study was based on a retrospective analysis of post-mortem records covering a four year period (July 2010 to July 2014). Results: A total of 213 individual animals were recorded dead during the four year period (July 2010 to July 2014). Out of this, 12 (5.6%) were recorded with C. tenuicollis. More females (8) than males (4) were recorded to have C. tenuicollis, although this was not statistically significant (P = 0.373. 7). Conclusions: This study shows that, Arabian oryx, beisa oryx, fringe-eared oryx, gemsbok and scimitar-horned oryx are susceptible to C. tenuicollis. Based on the epidemiology and the life cycle of this parasite, it is possible that these captive animals ingested the parasite through contaminated feed which could have happened in the pasture land or stray dogs and wild canidae (e.g. fox) visited the zoo contaminating the oryx feed. Stray dogs and wild canidae should be prevented from visiting pasture land and a captive animal facility.