Performance of an innovative gravity-driven micro-filtration technology for roof rainwater treatment

Abstract

Rainwater harvesting has become an important strategy to achieve the goal of sustainable development in urban areas. The latest emerged gravity driven micro-filtration technology can effectively reduce turbidity and bacteria to a very low level but still have disadvantages of low removal of dissolved organic substances and low permeate flux. An innovative gravity driven micro-filtration technique using ceramic flat sheet membrane as filter module was established and introduced to the treatment of rainwater that was harvested from a typical official building in GuangZhou, South China. The performance of this process has been evaluated in terms of pollutants (e.g. pH, turbidity, total dissolved solids (TDS), CODcr, NH3-N, DOC,UV254, total Coliforms and E.coli) removal efficiency, and the permeate flux profiles. Results shows that the removal rates of turbidity, TDS, CODcr, NH3-N, DOC,UV254, Coliforms and E.coli were 92.2%, 91.9%, 65.5%, 42.6%, 76.9%, 61%, 96.9% and 95.5%, respectively. The GDM system can run continuously for 60 days without back washing, and the permeate flux stabilized at 22~45 L/(m<sup>2</sup>·h) under a constant water head of 20 kPa. Experimental results demonstrated that the GDM system employing a ceramic flat membrane can significantly improve the organics removal in rainwater.

Laundry Waste Filtration Performance at Ultra Low Pressure

“…Based on the displayed flux profile, it can be categorized into 5 trends, the first trend is from the first day to -8, the next stage stretches from the 8th day to the next -16th day. This is in accordance with research conducted by [8], [23], [24]. On the 8th day, a period of stable flux levels was observed, the impurity layers became precipitating materials of different sizes such as bacteria, colloids, organic particles and inorganic substances.…”

“…These biofilms may play an important role in removing degradable organic pollutants from laundry waste. This was reported in the study by [8], where it was proven that many microorganisms gathered on the surface of the membrane and grew during long-term filtration which began to form from the 20th day and continued to increase until the 60th day, making the GDM process develop into a bio-reactor ( MBR), thereby contributing to the degradation of organic matter. In this study the initial permeate flux of the GDM reactor decreased rapidly with increasing operating duration.…”

“…The GDM system has generally increased contaminant removal efficiency through filtration with a nominal pore size of the membrane which is 0.1 μm and the size of dissolved organic matter less than 100 nm in diameter. Thus, these molecular contaminants cannot be rejected through the microfiltration process in the GDM system [8]. The Gravity Driven Membrane (GDM) Filtration Method is a membrane technology method that does not require high energy and costs a lot.…”

Rainwater Harvesting and Treatment: State of the Art and Perspectives

“…However, single MF units can only eliminate a fraction of large-diameter organics and pathogens, so they are not very effective as a rainwater treatment technique [115]. Thus, Shiguang et al [116] recommend membrane surface modifications or combined use with other water treatments for effectively improving the performance of MF techniques in rainwater treatment. Nonetheless, considering the current advancements in MF techniques, there are ample reasons to believe that MF techniques have a future use for rainwater treatment [117].…”

Application of the Ultrafiltration and Photooxidation Process for the Treatment of Rainwater

“…For example, Kudlek (Kudlek, 2020) also reports that in the rainwater microfiltration system, the coefficients of turbidity removal, COD, NH 3 -N, DOC, coliforms, and E. coli were 92.2%, 65.5%, 42.6%, 76.9%, 96.9%, and 95.5%, respectively. Rainwater filtration could be carried out for 60 days without backwashing, and the permeate flux stabilized at ~ 22-45 L/m 2 •h at a constant water pressure of 20 kPa (Shiguang et al, 2021). Teixeira and Ghisi (Teixeira & Ghisi, 2019) assessed the performance of granular and membrane filters.…”