Degradation of organic matter using a submerged micro bubble diffuser in a biological wastewater treatment system

Abstract

Abstract.In most biological wastewater treatment systems, aeration is provided using millimetre diffusers of various sizes. The aeration is to provide mixing, as well as oxygen, for the microorganisms in the degradation of organic matter. In this study, the effectiveness of using micro diffusers in the degradation of organic matter was evaluated. Two reactors A and B, of size 140x140x500 mm, were constructed using Perspex to treat municipal wastewater. Aeration in reactors A and B was provided using a millimetre diffuser and a micro diffuser, respectively. The diffusers consist of perforated aluminium plate to generate millimetre bubbles and sintered porous glass to generate micro bubbles. Compressed air was forced through two parallel flow meters at a flow rate of 2.5 L/min. Biomass for both reactors were acclimatized prior to treating the municipal wastewater in the reactors. Two batch experiments were conducted at 26°C for the estimation of the kinetic parameters for the degradation of organic matter. Samples were evaluated for chemical oxygen demand (COD) and soluble chemical oxygen demand (sCOD) for both reactors at approximately 1 hour, 3 hours, and 6 hours, respectively, until 48 hours, for each batch of experiment. From the results of the study, it was found that for the micro and millimetre diffusers, the degradation kinetic parameter k COD was 0.041 and 0.028, respectively, for COD and k sCOD was 0.060 and 0.044, respectively, for sCOD. On average, the micro and millimetre diffusers removed COD at approximately 87% and 81%, respectively, and removed sCOD at approximately 91% and 75%, respectively. It can be concluded that the use of a micro diffuser can provide a higher degradation of organic matter.Waste Management and the Environment V 415

Physical Properties and Durability of Lime-Cement Mortars Prepared with Water Containing Micro-Nano Bubbles of Various Gases

“…The use of micro-nano bubble water for efficient removal of microbiological pollution from various surfaces [ 8 ] may be an alternative for the chemicals used in cleaning agents which cause irritation of skin or the respiratory system. Moreover, it has a beneficial effect on the growth of organisms, as well as find wider application in the treatment of wastewater [ 19 , 20 ]. Studies also prove that the oxygen micro-nano bubble water accelerates the growth of plants, increases blooming, has a bactericidal effect and improves the soil structure [ 21 ].…”

Gas nanobubble dispersions as the important agent in environmental processes – generation methods review

“…Membranes and sintered ceramics are commonly used in bubble generation studies (Fujikawa et al ., 2003; Kukizaki and Goto, 2006; Kukizaki and Baba, 2008; Kukizaki and Wada, 2008; Zimmerman et al ., 2008, 2011; Kutty et al ., 2010; Khirani et al ., 2012; Ulatowski and Sobieszuk, 2018). However, immersing the membrane in liquid and pressurizing gas through pores is not sufficient for generating bubbles in micro‐ and nanoscale (Kukizaki and Goto, 2006; Kukizaki and Wada, 2008; Zimmerman et al ., 2008).…”

“…Usage of ozone results in generation of even more radicals (Von Gunten, 2003). Both oxygen and ozone nanobubbles reduce COD by even 90%, depending on the initial COD and composition of the wastewater (Kutty et al, 2010;Yang et al, 2012). Oxygen and ozone were used to (1) ΔP = 2 r decolourize the wastewater from textile industry (Chu et al, 2007) and reduce the concentration of pesticides in both the water and ground originating from the heavy polluted fields (Ikeura et al, 2011).…”

“…Most of the particles and oils are removed during the flotation. Micro‐ and nanobubbles, because of their very low rising velocity, are able to disperse in whole volume of the tank and reach places which cannot be reached by bigger bubbles (Kutty et al ., 2010; Rocha e Silva et al ., 2018). Additionally, the usefulness of bubbles in flotation is increasing proportionally to the decrease of bubble diameter.…”

“…Dispersions of extremely fine gas spheres in liquid possess some extraordinary characteristics which show them as a very promising tool in various branches of industry. In present times, nanobubbles are most commonly used in environmental science and industry, such as wastewater treatment (Chu et al ., 2007; Kutty et al ., 2010; Etchepare et al ., 2017a; Temesgen et al ., 2017), pesticide removal (Ikeura et al ., 2011), promotion of growth of both plants and animals (Ebina et al ., 2013; Ahmed et al ., 2018a), field irrigation (Minamikawa et al ., 2015), etc. Apart from environmental studies, nanobubbles are used in medical studies for example as the contrast for USG imaging (Krupka et al ., 2010).…”