Fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration

Abstract

Understanding the fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration is essential to assess the impact of wastewater effluent on the post treatment requirements of riverbank filtrates. Furthermore, their fate during drinking water treatment can significantly determine the process design. The objective of this study was to characterise bulk organic matter which consists of EfOM and NOM during riverbank filtration using a suite of innovative analytical tools. Wastewater effluent-derived surface water and surface water were used as source waters in experiments with soil columns. Results showed the preferential removal of non-humic substances (i.e. biopolymers) from wastewater effluent-derived surface water. The bulk organic matter characteristics of wastewater effluent-derived surface water and surface water were similar after 5 m soil passage in laboratory column experiment. Humic-like organic matter in surface water and wastewater effluent-derived surface water persisted through the soil passage. More than 50% of total dissolved organic carbon (DOC) removal with significant reduction of dissolved oxygen (DO) was observed in the top 50 cm of the soil columns for both surface water and wastewater effluent-derived surface water. This was due to biodegradation by soil biomass which was determined by adenosine triphosphate (ATP) concentrations and heterotrophic plate counts. High concentrations of ATP in the first few centimeters of infiltration surface reflect the highest microbial activity which correlates with the extent of DOC reduction. Good correlation of DOC removal with DO and biomass development was observed in the soil columns.

Effects of effluent organic matter characteristics on the removal of bulk organic matter and selected pharmaceutically active compounds during managed aquifer recharge: Column study

“…In contrast to oxic conditions, specific ultraviolet absorbance (SUVA) values were found to be decreased under anoxic conditions, implying that the degradation of aromatic OM was relatively higher . Some of the authors of this paper have previously reported the fate of bulk organic matter during soil oxic soil passage conditions, but this study did not make a comparison between such oxic and anoxic conditions (Maeng et al, 2008). Redox conditions during soil passage affect the fate of bulk OM and the behavior of PhACs that are sensitive to redox conditions.…”

Riverbank filtration for the treatment of highly turbid Colombian rivers

“…Jüttner (1995) determined that the schmutzdecke and the upper layers were responsible for most of the elimination of volatile organic carbon, and Dizer et al (2004) concluded that this layer is extremely efficient in eliminating viruses. Maeng et al (2008) found that 50 % of the total dissolved organic matter removal in a simulated RBF system occurred in the first few centimeters of the infiltration surface due to the biological activity in the developed biomass. In the schmutzdecke, the removal of organic matter, pathogens and chemicals occurs through predation, scavenging and metabolic breakdown mechanisms (Haig et al, 2011).…”

“…The interface between the surface water and the groundwater, corresponding to the hyporheic zone ( Fig. 1), plays the most important role in the degradation of contaminants (Doussan et al, 1997;Grischek and Ray, 2009;Maeng et al, 2008;Smith et al, 2009;Stuyfzand, 2011). The hyporheic zone is characterized by redox gradients, the dynamic exchange of oxygen and the presence of organic carbon and microorganisms (Doussan et al, 1997;Febria et al, 2012;Findlay and Sobczak, 2000) that enhance electron transfer, ion exchange and degradation and sorption processes, therefore improving the removal of pollutants (Hiscock and Grischek, 2002;Smith, 2005;Tufenkji et al, 2002).…”

Novel chemical and biological pre-treatments to improve water quality in drinking water treatment

“…However, fewer studies have been performed to determine the performance of RBF in removing NOM and DBP precursors during higher hydraulic gradient conditions. One study showed that in a lab-scale RBF system the removal of the bulk organic matter was not distinguishable at hydraulic loading rates of 0.625 and 1.25 m/day (Maeng et al, 2008b). The same results were observed in a pilot slow sand filtration system (Collins et al, 1992).…”

“…The short-term shock loadings could also impact the redox conditions inside the biofilter. Under normal conditions, DO was rapidly consumed in the first 1 m filtration length, reaching a concentration below 1 mg/L at that sample point (Table 8- DO is the main electron acceptor for oxic biodegradation, and the DO consumption amount correlates well with the removal of NOM (Maeng et al, 2008a). Generally, as shown in Figure 8 change profiles, this increased DOC removal (relative to the DO consumption) could be ascribed to the anaerobic biodegradation processes taking place under these conditions (Liu et al, 2016a).…”