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This section covers research published during the calendar year 2018 on mixing and transport processes. The review covers mixing of anaerobic digesters, mixing of heat transfer, and environmental fate and transport., (© 2019 Water Environment Federation.)

Worldwide waste generation has become a topic of interest since the accumulation of this waste has prompted environmental hazards. Among which, anaerobic digestion provides green and efficient alternate solution for removal of toxic waste and energy production. Therefore, this review emphasizes on the recent data published in 2018 on topics related to anaerobic process, enhancement of biogas production, and fermentation efficiency. Furthermore, more focus was made on the factors influencing anaerobic digestion and the effect of trace elements as ionic salts as well as nanoparticles on overall biogas production, respectively. PRACTITIONER POINTS: Anaerobic digestion provide green and efficient alternate solution to deal with. This review focused on the conditions related to anaerobic process to improve biogas production and fermentation efficiency. The trace elements were focused on how to influence biogas production during anaerobic digestion., (© 2019 Water Environment Federation.)

A review of the literatures published in 2017 on topics relating to anaerobic process issues in the improvement of biogas production and fermentation efficiency of various kinds of organic waste. New process methodology and technology of digestion is also presented. This review is divided into the following sections: pretreatment, organic waste and co-digestion, multiple-stage process, process methodology and technology.

This section covers research published during the calendar year 2016 on mixing and transport processes. The review covers mixing and transport of anaerobic digesters.

This study tests a hydrogen-based membrane biofilm reactor (MBfR) to investigate simultaneous bioreduction of selected oxidized contaminants, including nitrate (-N), sulfate (), bromate (), chromate (Cr(VI)) and para-chloronitrobenzene (p-CNB). The experiments demonstrate that MBfR can achieve high performance for contaminants bioreduction to harmless or immobile forms in 240 days, with a maximum reduction fluxes of 0.901 g -N/m2·d, 1.573 g /m2·d, 0.009 g /m2·d, 0.022 g Cr(VI)/m2·d, and 0.043 g p-CNB/m2·d. Increasing H2 pressure and decreasing influent surface loading enhanced removal efficiency of the reactor. Flux analysis indicates that nitrate and sulfate reductions competed more strongly than , Cr(VI) and p-CNB reduction. The average H2 utilization rate, H2 flux, and H2 utilization efficiency of the reactor were 0.026 to 0.052 mg H2/cm3·d, 0.024 to 0.046 mg H2/cm2·d, and 97.5% to 99.3% (nearly 100%). Results show the hydrogen-based MBfR may be suitable for removing multiple oxidized contaminants in drinking water or groundwater.

In this paper, bioaugmentation was applied to upgrade a full-scale activated sludge system (S2) into a contact oxidation system (S1). Results showed that when chemical oxygen demand (COD) and ammonia nitrogen (NH(4)(+)-N) concentration of the petrochemical wastewater were 320-530 mg/L and 8-25mg/L, respectively, the bioaugmented process (S1) took only 20 days when they were below 80 mg/L and 10mg/L, respectively. However, the unbioaugmented conventional activated sludge process (S2) spent 30 days to reach the similar effluent quality. As the organic loading rate (OLR) increased from 0.6 to 0.9 and finally up to 1.10 kg COD/m(3)d, S1 showed strong resistance to shock loadings and restored after three days compared to the seven days required by S2. Based on the results of this paper, it shows that bioaugementation application is feasible and efficient for the process upgrade due to the availability of the bioaugmented specialized consortia.