NANOBUBBLE SYSTEMS APPLICATIONS
Waste Water Treatment
Aeration is used in water and wastewater treatment processes to deliver oxygen to microorganisms responsible for the biological oxidation of carbonaceous material and ammonia. Aerobic processes are used to degrade biochemical oxygen demand (BOD), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), and ammonia from water. One of the fundamental control parameters in aerobic processes is dissolved oxygen (DO). Many treatment processes lack sufficient DO due to excess loading, underperforming aeration systems or antiquated designs. Low DO levels encourage the growth of filamentous bacteria that can cause process upsets related to sludge bulking and foaming. Furthermore, low DO levels can result in poor treatment efficiency and lead to potential discharge violations. Adding additional aeration capacity can be complex and costly; however, the addition of nanobubbles can be used to supplement underperforming aeration systems by applying biologically available DO exactly where it is needed to support the biological process in quick, cost-effective and modular fashion.
Membrane bioreactors (MBR)
Membrane bioreactors (MBR) have been widely applied at industrial facilities to provide pretreatment of wastewater prior to discharge to the collection system. One of the advantages of an MBR system is that it provides a high degree of treatment in a compact footprint, in part because it is operated at high mixed liquor suspended solids (MLSS) concentrations ranging from 8,000 to 18,000 mg/L. A common problem encountered with industrial MBRs is the inability to maintain the target dissolved oxygen (DO) level during peak loading events. This is partially attributed to the nature of industrial wastewater, which is typically inconsistent in water quality and flow, resulting in periods of low influent loading followed by high influent loading. This dramatic change in loading may cause a sudden spike in oxygen uptake rate in the aeration basin immediately followed by a sustained decline in DO. If the oxygen-transfer system is not able to recover by supplying the DO required to support the biological system, BOD removal across the MBR will decline. The capital expenditure required to expand or upgrade an undersized aeration system can be substantial, often with limited to no return on investment across the expected useful life of the equipment. However, the application of nanobubbles in wastewater treatment provides cost-effective supplemental aeration for MBRs.
Most offensive odours produced in wastewater are the gaseous by-product of decomposed organic matter. The most common of these is hydrogen sulphide, commonly referred to by its chemical formula H2S, which is formed from the anaerobic degradation of organic matter containing sulphur or from mineral sulphates and sulphites. Hydrogen sulphide is known for its rotten egg smell and can adversely impact human health at levels above 10 ppm. Odour in sewer lines, collection points, treatment plants, and ponds can lead to public complaints and reduces aesthetic value. One means of treating odours, including H2S, is to prevent the water from going anaerobic by increasing dissolved oxygen (DO) or oxidation reduction potential (ORP) using air, oxygen or other oxidants. Nanobubbles effective gas-injection technology delivers a high volume of air or oxygen nanobubbles, efficiently maintaining DO and preventing the anaerobic conditions that lead to odorous compound formation.