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The Moving Bed Biofilm Reactor has proven to be an efficient system in wastewater treatment and has become a viable solution for small treatment plants. The main objective of this research was to analyse the performance of a moving bed reactor using low-cost local material when fed with municipal wastewater. A pilot reactor with a total volume of 900 litres was built and it was fed continuously with municipal wastewater. The operation of the system was adjusted to six different organic loading rates. The biofilm carrier was polyethylene tubing with internal diameter of 1.1 cm, cut into pieces of 1.2 cm. The tested material offered a specific surface area of 590 m2/m3. Air was provided with a fine-bubble diffuser. The main results show that the reactor performance was stable and predictable. The COD removal confidently behaves according to a general hyperbolic kinetic equation. The maximal total COD removal attained was 81%. Nitrification was observed only for organic loads with values under 5.7 gCOD/m2·d. Good adherence of the microorganisms was observed for the applied organic loading rates. After several months of operation, the material showed no signs of abrasion or deformation. The sludge production behaved linearly with the organic load reaching 979 gTSS/d with the highest organic load of 35.7 gCOD/m2·d. The amount of microorganisms attached to the carrier increased with the organic load tending to an asymptotical maximal value of 17.3 g/m2 (as dry solids). Mean cellular retention times from 2.0 to 23.1 days were determined.

The possibility of joining biological phosphorus and nitrogen removal in a biofilm sequencing batch reactor was studied using an operation strategy with four reaction phases: Anaerobic/Aerobic/Anoxic/Aerobic. A 1,000 liter pilot scale reactor, filled with Pall-Rings as biofilm support was fed with municipal wastewater. After operating the system for 615 days, optimal operation conditions were establish to obtain highest removal rates with a well established microbial community. Adequate cycle and phase duration were established and organic loading values were obtained for different treatment purposes. The system worked successfully obtaining removals of COD, phosphates and ammonia nitrogen of 89 ± 1%, 75 ± 15%, and 87 ± 10%, respectively. The high removal efficiencies of P and N were obtained thanks to the establishing relationship between nitrifying bacteria and phosphate accumulating bacteria.

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This research describes Biological Phosphorus Removal at Organic Loading Rates from 5 to 30 g COD/m2·d using a laboratory scale Sequencing Batch Biofilm Membrane Reactor. The reactor was fed with synthetic wastewater based on sodium acetate with a COD:N:P ratio of 20:5:1. An average PO4-P removal of 72% was observed when the organic load was kept under 15 gCOD/m2·d. Maximum PO4-P removal of 85% was associated with a consumption rate of 700 mgPO4-P/m2·d. Increasing with the organic load, the PO4-P released during the anaerobic phase averages 40% over the influent concentration, showing a maximum value of 107%. Throughout the experiments, overall COD removal rates were above 90%, and the COD uptake during the anaerobic phase ranged between 60 and 80% for organic loading rates under 15 gCOD/m2·d. Simultaneous nitrification and dentrification took place during the transition from aerobic to anaerobic conditions at the beginning of every cycle. Average transformation rates between 0.6 to 2.0 gNH4-N/m2·d and 0.3 to 1.2 gNO3-N/m2·d were observed for organic loading rates under 15 gCOD/m2·d, corresponding to average NH4-N removal rates between 50 and 70%. Average effluent NO3-N ranged between 1.5 and 10.6 mg/l. Phosphorus contents of the biofilm based on dry mass ranged between 4.2 and 5.2%.