Performance of a Full‐Scale Biofilm System Retrofitted with an Upflow Multilayer Bioreactor as a Preanoxic Reactor for Advanced Wastewater Treatment

Abstract

To enhance nitrogen removal in an existing microbial contact oxidation (MCO) system with a treatment capacity of 900 m 3 /d, an upflow multilayer bioreactor (UMBR) was chosen as a preanoxic reactor for the removal of organic matter and nitrate. The removal performance of the retrofitted plant was evaluated during the startup phase at a low temperature in winter. The high removal (.80%) of organic matter and suspended solids in the UMBR provided stable nitrification conditions in the MCO system, as a result of the substantial reduction in organic matter and solids loaded onto the MCO system. This treatment system showed a stable nitrogen removal efficiency of 75.3%, even in the low temperature range 7 to 108C. Phosphorus was completely removed by chemical precipitation. Production rates of excess sludge, as a function of the loads of influent flowrate and biological oxygen demand (BOD), were 0.022 kg dry solid/m 3 wastewater and 0.132 kg dry solid/kg BOD. Water Environ. Res., 80, 757 (2008).

Horizontal Biofilter System in Tapioca Starch Wastewater Treatment: The Influence of Filter Media on the Effluent Quality

“…The use of sand as a biofilter media gave a better performance indicated by high BOD removal efficiency at 98.53%. This result was slightly similar to the BOD removal efficiency of 99% found by An et al (2008) who studied about sand filtration in sewage treatment in Korea. The high BOD removal efficiency obtained from the sand biofilter was due to its characteristics which has a high porosity between its particles, thus giving more surface area for the bacteria to form the biofilms and allowing wastewater to have a maximum contact with the biofilm on the particles, therefore the removal of organic material in wastewater stream was more effective.…”

“…Using sand as biofilter media gave an average COD concentration of 82.2 mgl -1, giving the highest percentage reduction of 98.71% Bamboo plait biofilter media; however showed the lowest removal efficieny of 90.18% with the average COD concentration of 625.4 mg l -1 , much higher than the acceptable value for TSW effluent discharge. This value was slightly higher than the values of 92 -94% for anaerobic and 94 -96% for aerobic condition reported in a previous study (Mai, 2006), and much higher than that found by An et al, (2008) at 91.8%. Sand biofilter media combined with circulation, which applied in a synthetic dairy wastewater treatment, reduced COD concentration by 99.3% (Healy et al, 2004).…”

“…The results showed that the high TSS removal efficiency obtained from treatment using sand as a biofilter media with the average value of 91.19%, while the bamboo plait biofilter media gave the lowest value at 52.37 %. These values were lower than the 90.6 -95.8 % reported by Mai (2006) and An et al, (2008). The low percentage reduction of TSS concentration using bamboo plait as a biofilter media was due to a degradation and suspension of some part of this media into the waste stream.…”

Toxic Effects of Single-Walled Carbon Nanotubes in the Development of E. coli Biofilm

“…Biofilm formation begins with the adhesion of single cells to the substratum, followed by cell proliferation and exopolymeric substances (EPS) production . These sessile communities can have a number of beneficial applications, such as biocontrol agents by preventing infections in certain plants , in situ remediation , and breakdown of organics in wastewater treatment plants , . However, biofilms can also have deleterious effects, causing antibiotic-resistant infections , , clogging of pipes , , and contaminating food in industrial settings .…”

Resistance of oxidative stress in biofilm and planktonic cells

“…The most common explanation of the bacterial biofilm durability is the mechanism of secretion of antibiotic-degrading enzymes, which reduces the possibility of penetration of the antimicrobial substances to the lower layers of cells (Stewart and Costerton 2001;Obst et al 2006;Chaignon et al 2007;Hoiby et al 2010;Banerjee et al 2011) . Another common argument is based on emerging multi-layer construction of the structure of the biofilm, which also impedes the penetration of antimicrobial substances (Etienne et al 2005;An et al 2008). Another reason for the increased resistance of biofilm cells is connected with the observation based on the presence of cells at different stages of development (Chavant et al 2004;Gad et al 2004).…”