Operational parameters required for the start-up process of a biofilter to remove Fe, Mn, and NH3-N from low-temperature groundwater

Abstract

A B S T R A C TStart-up experiments were carried out using a constructed a pilot-scale biofilter in a water supply plant to purify iron (Fe), manganese (Mn), and ammonia (NH 3 -N) from low-temperature groundwater (3-4˚C throughout the year). The results of the biofilter operation indicated that the simultaneous removal of these contaminants could be obtained with a one-stage biofilter, while the operational parameters such as aeration and backwashing strength (BWS) should be optimized during the start-up operation period. Removal of Fe was most likely dominated by chemical oxygen oxidation since the biofilter exhibited high removal efficiency at the initial running period and the start-up time was not required. Higher levels of aeration (that corresponds to higher dissolved oxygen concentration) helped to transform the water redox environment and increase Mn removal. Nitrification effects were irrelevant with the extra aeration. A weaker BWS was helpful in avoiding biomass loss during the initial operation of the biofilter; however, the BWS should be improved to eliminate excess amounts of metal oxide accumulation after a long operation time, since it could enhance the overall removal. Using high-throughput sequencing technology, the functional bacteria genera were identified. It was demonstrated that the corresponding functional oxidizing bacteria could be acclimated sufficiently in low-temperature water.

Comprehensive analysis of the start-up period of a full-scale drinking water biofilter provides guidance for optimization

“…Similar amounts of Leptothrix were found near the bottom of Filter 1 (190 cm, Fig. 7), which may be due to possible involvement of this genus in manganese removal (Bruins et al, 2015a;Cai et al, 2016). The highest amount of AOB (∼ 10 7 copies g −1 filter medium) was found at a depth of 50 cm (Fig.…”

“…A comparison of the length of the start-up period from various studies in the literature is virtually futile, largely due to diverging experimental conditions and focus. For example, a long start-up period of around 6 months was found at unusually cold temperatures of 3-4 • C (Cai et al, 2016). In other studies, not all relevant electron donors such as ammonium (Zeng et al, 2010), manganese (Lytle et al, 2007) or iron (Bruins et al, 2015b) were included.…”

Autochthonous tropical groundwater bacteria involved in manganese(ii) oxidation and removal

“…2,7,8 Although these techniques are efficient, they generate large volumes of sludge and have high operating and maintenance costs. 9,10 For this reason, many studies have focused on Mn removal methods that include the use of microorganisms (biofiltration) at the pilot [11][12][13][14] and large scale. [15][16][17][18][19][20][21][22][23] Biological treatments are more environmentally friendly and less expensive than conventional systems, since they reduce the use of chemical products, the production of sludge, and the associated costs.…”

The Use of Chalcedonite as a Biosorption Bed in the Treatment of Groundwater

“…Nitrification is a completely aerobic process, and so oxygen consumption indicates that biological processes are taking place on the filters. The total stoichiometric oxygen consumption in the nitrification reactions is 4.57 g O 2 per 1 g of ammonium nitrogen, whereas, in the case of iron and manganese oxidation, they are 0.14 g O 2 /g Fe and 0.29 g O 2 /g Mn, respectively [46]. In single-stage filtration with a water table above the filtration layer, in conditions of full saturation of water with oxygen (10-16 • C), it is possible to oxidize no more than approximately 2 g of N-NH 4 + /m 3 .…”