Submerged Membrane System with Biofilter as a Treatment to Rainwater

Abstract

Rainwater has been used as drinking water in Thailand for centuries especially in the rural parts and is accepted as an important water resource. From past to present, the quality of rainwater has changed with the land use of the landscape and its water quality is influenced by a diverse range of conditions such as the management of pollutant sources, the catchment condition, wind and meteorological conditions and the location of rainwater collection points. In this study, the quality of rainwater collected off roofs at several locations was examined. Granular activated carbon (GAC) filtration was used as a pretreatment to microfiltration to remove the dissolved organic matter (DOC). After an initial adsorption period, the biofilm that formed on the GAC (biofilter) was found to remove DOC by up to 40 %, 35 % and 15% for bed filter depths of 15 cm, 10 cm and 5 cm respectively. Biofilters also removed nitrate and phosphate by more than 80% and 35%. The hollow fibre membrane micro filtration with pore size of 0.1 m µ was used to treat the effluent from biofiltration to remove the microorganisms/pathogens in the rainwater. Although there was no significant additional removal of DOC by MF, the biofilter removed all microorganisms. The use of biofilters as pretreatment to MF/UF could remove a higher amount of DOC, remove microorganisms, increase the membrane treatment efficiency, and reduce membrane fouling.

A Review of Roof Harvested Rainwater in Australia

“…As with surface water, rainwater can be contaminated with coarse and fine particulate matters, chemicals, microorganisms, metals, and ionic elements, which may be detrimental health effects [ 76 , 77 ]. Previous studies have suggested that the human health consequences associated with rainwater are low in intensity and are linked to the type of rainwater harvesting systems design and maintenance [ 64 , 78 ].…”

Development and economic viability analysis of photovoltaic (PV) energy powered decentralized ultrafiltration of rainwater for potable use

“…However, this process had a marginal impact in reducing total heterotrophic bacteria. Activated carbon treatment based on membrane filtration to remove dissolved organic solids (DOCs) demonstrated limited contaminants removal efficiency [15]. For example, the use of antimicrobial silver ions in combination with settling tanks and conventional filtration was investigated by Adler et al [16].…”

Laws and Mechanism of the Fe (III) Clogging of Porous Media in Managed Aquifer Recharge

“…The presence of oxygen or nitrate in recharge water can stimulate bacteria and produce iron or manganese oxides and hydroxide precipitates [8]. The stormwater quality data extracted from the literature (Table 1) show that iron is the most common metal pollutant in stormwater [6,[9][10][11][12][13][14], and the iron content ranges from 0.3 to 1.8 mg/L, generally exceeding the Australian Drinking Water Guidelines(AWDG) [15] standard. The total iron concentration specified in the water quality standard for reclaimed water recharge in China (GB/T 19772-2005) stipulates that the limit value of the total iron concentration is 0.3 mg/L; in Beijing, it is 0.3-1.0 mg/L [14]; for most states in America, it is 0.3 mg/L [16,17]; and in the former Soviet Union, it is 3 mg/L [18].…”