Abstract
Effective orthophosphate removal strategies are needed to counteract eutrophication and guarantee water quality. Previously, we established that hydrogen-oxidizing bacteria (HOB) have the ability to remove orthophosphate from artificial surface water. In the present study, we expand the application of the HOB orthophosphate removal strategy (1) to treat artificial surface water with low initial orthophosphate concentrations, (2) to treat real surface water and real wastewater effluent, and (3) to remove orthophosphate continuously. For synthetic surface water, irrespective of the initial concentration of 0.7, 0.5, 0.3, and 0.1 mg PO43−-P/L, ultra-low concentrations (0.0058 ± 0.0028 mg PO43−-P/L) were obtained. When artificial surface water was replaced by real surface water, without added nutrients or other chemicals, it was shown that over 90% orthophosphate could be removed within 30 min of operation in a batch configuration (0.031 ± 0.023 mg PO43−-P/L). In continuous operation, orthophosphate removal from surface water left an average concentration of 0.040 ± 0.036 for 60 days, and the lowest orthophosphate concentration measured was 0.013 mg PO43−/L. Simultaneously, nitrate was continuously removed for 60 days below 0.1 mg/L. The ability to remove orthophosphate even under nitrogen limiting conditions might be related to the ability of HOB to fix nitrogen. This study brings valuable insights into the potential use of HOB biofilms for nutrient remediation and recovery.
Highlights
Effective orthophosphate removal strategies are needed to counteract eutrophication and guarantee water quality
When artificial surface water was replaced by real surface water, without added nutrients or other chemicals, it was shown that over 90% orthophosphate could be removed within 30 min of operation in a batch configuration (0.031 ± 0.023 mg PO43−-P/L)
Within the operational time of 3 h, the initial orthophosphate concentrations of 0.7, 0.5, 0.3 and 0.1 PO43−-P mg/L were decreased to 0.0080 ± 0.0010, 0.0080 ± 0.0010, 0.0055 ± 0.00052, 0.0015 ± 0.00052 mg PO43−-P/L, respectively (Table 2)
Summary
Effective orthophosphate removal strategies are needed to counteract eutrophication and guarantee water quality. We established that hydrogen-oxidizing bacteria (HOB) have the ability to remove orthophosphate from artificial surface water. Hydrogen-oxidizing bacteria (HOB) were introduced as a novel strategy to remove phosphorus, as orthophosphate, to levels below 0.01 mgP/L (Barbosa et al, 2020). Because the orthophosphate removal process is dependent on HOB growth, the orthophosphate removal efficiency can be improved by increasing the biofilm surface area with respect to the treated water volume. Another advantage that the HOB provide is that the produced biomass can be used, for instance, as an organic fertilizer A schematic representation of the setup is depicted in Fig. S1 (Supplementary Information)
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