Exploratory study of municipal wastewater primary sedimentation basin effluent treatment using an upflow anaerobic filter

This report describes the results of exploratory tests conducted using a 95-liter upflow anaerobic filter (UAF) bioreactor test unit fed raw primary sedimentation basin effluent at a municipal wastewater treatment plant. The main objectives of the exploratory study were to obtain substrate conversion and hydraulic data for use in making full-scale projections, evaluate potential biofilm support materials, and to assess the suitability of the upflow anaerobic filter unit process as part of a new concept for a complete municipal wastewater treatment plant. The tests were conducted using available equipment with no effort made to optimize the system. The main findings of the tests are: COD loading rate: 2,1 kg COD/m3/day, hydraulic retention time: 3 hours, average influent energy conversion: 71% (Influent HHV -effluent HHV), biogas CH4 content up to 65%, stable operation at 16°C, evaluation of different biofilm support materials (see text), non-biodegradable ash and phenolic compounds account for at least 63% of the total solids contained in primary sedimentation basin effluent and they are the most important contributors to turbidity.

Characterization of a hybrid sequencing batch reactor system for treatment of wastewater using suspended microbial aggregates and biofilms

A moving bed biofilm reactor was studied for its capability of carbon oxidation and nitrification. The hybrid system made use of suspended biomass in the forms of microbial aggregates and attached biomass in the form of biofilms on suspended carriers. The carriers used for biofilm support were made of polyethylene and have a wagon wheel shape. The carrier fill ratio, which is defined as the volume ratio of carrier to the whole reactor was a key characteristic parameter of the reactor. The experimental runs used different carrier filling ratios from 25 to 50% to determine the optimal operating value for this type of hybrid reactor. Also the nutrient conditions were modified to test the capacity of the system to adapt to various changes in phosphorus loading in the influent wastewater. The results showed that for an influent chemical oxygen demand (COD) of 600 mg/L, ammonia of about 24 mg/L and hydraulic reaction time of 6 hours there was no difference in the performance of the system under the different carrier filling rations.

Characterization of a hybrid sequencing batch reactor system for treatment of wastewater using suspended microbial aggregates and biofilms

A moving bed biofilm reactor was studied for its capability of carbon oxidation and nitrification. The hybrid system made use of suspended biomass in the forms of microbial aggregates and attached biomass in the form of biofilms on suspended carriers. The carriers used for biofilm support were made of polyethylene and have a wagon wheel shape. The carrier fill ratio, which is defined as the volume ratio of carrier to the whole reactor was a key characteristic parameter of the reactor. The experimental runs used different carrier filling ratios from 25 to 50% to determine the optimal operating value for this type of hybrid reactor. Also the nutrient conditions were modified to test the capacity of the system to adapt to various changes in phosphorus loading in the influent wastewater. The results showed that for an influent chemical oxygen demand (COD) of 600 mg/L, ammonia of about 24 mg/L and hydraulic reaction time of 6 hours there was no difference in the performance of the system under the different carrier filling rations.

Comparative Anaerobic Decolorization of Azo Dyes by Carbon-Based Membrane Bioreactor

This study used a novel integrated technology of ceramic supported carbon membrane (CSCM) to degrade azo dyes through an anaerobic mixed culture. The CSCM worked simultaneously as biofilm support, redox mediator, and nano-filter to enhance the dye decolorization efficiency. The decolorization of Acid Orange 7 (AO7) was initially investigated with and without microorganisms in both ceramic support (CS) and CSCM reactors. The CSCM bioreactor (B-CSCM), operated with microorganisms, gave a maximum decolorization of 98% using a CSCM evolved from 10% weight (wt.) of Matrimid 5218 solution. To know the influence of permeate flow, feed concentration, and dye structure on the decolorization process, different B-CSCMs for dye removal experiments were studied over monoazo AO7, diazo Reactive Black 5 (RB5), and triazo Direct Blue 71 (DB71). The highest color removal, operated with 50 mg·L−1 feed solution and 0.05 L·m−2·h−1 of permeate flux, was 98%, 82%, and 72%, respectively, for AO7, RB5, and DB71. By increasing these parameters to 100 mg·L−1 and 0.1 L·m−2·h−1, the decolorization rate of dye solution still achieved 37% for AO7, 30% for RB5, and 26% for DB71. In addition, the system was run for weeks without apparent loss of activity. These findings make evident that the combined phenomena taking place in CSCM bioreactor result in an efficient, cost-effective, and ecofriendly azo dye decolorization method.

Investigation of municipal wastewater treatment by agricultural waste materials in locally designed trickling filter for peri-urban agriculture

A pilot scale trickling filter system was designed, developed, and operated using a constant recirculation method for treatment of municipal wastewater. Maize cob (TF1) and date palm fibre (TF2) were used as biofilm support media in a trickling filter system. Both the TF1 and TF2 were compared based on the removal efficiency of pollution indicators such as biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), electrical conductivity (EC), total nitrogen (TN), total phosphorus (TP) and sulphates. The hydraulic flow rate and loading were set as 0.432 m3/h and 0.0064 m3/m2.minute, respectively at temperature range of 15–42 °C for 15 operational weeks. Both the TF1 and TF2 showed acceptable removal efficiency (61% to 76.3%) for pathogen indicators such as total count, fecal coliforms and E. Coli. However, 8–15% higher removal efficiency was observed for TF1 for all the pollution indicators compared to TF2. The results suggest that both the biofilm support media in trickling filter have potential to treat municipal wastewater in peri-urban small communities to produce environmentally friendly effluent.

Enhanced simultaneous nitri-denitrification in aerobic moving bed biofilm reactor containing polyurethane foam-based carrier media

Fluidization of carrier media for biofilm support and growth defines the moving bed biofilm reactor (MBBR) process. Major MBBR facilities apply virgin polyethylene (PE)-based circular plastic carrier media. Various carriers were studied to replace these conventional carriers, but polyurethane (PU) foam-based carrier media has not been much explored. This study evaluates the potential of PU foam carrier media in aerobic MBBR process for simultaneous nitri-denitrification (SND). Two parallel reactors loaded with conventional PE plastic (circular) and PU foam (cubical) carriers compared for their removal efficiencies of chemical oxygen demand (COD) and nitrogen contaminants from wastewater. Results indicate that average COD removal in MBBR containing PE plastic carrier media was 81%, compared to 83% in MBBR containing PU foam. Average ammonical and total nitrogen reduction was 71% and 59% for PU foam-based MBBR, compared to 60% and 42% for PE plastic-based MBBR. SND-based nitrogen removal capacity was doubled in aerobic MBBR filled with PU foam carrier media (27%), than MBBR containing PE plastic carrier media (13%). Cost economics also governs the commercial advantage for the application of PU foam-based carrier media in the MBBR process.