Four laboratory-scale sequencing batch reactors (SBRs) were operated to evaluate whether bioaugmentation with Acinetobacter spp. can be used to improve start-up and performance of enhanced biological phosphorus removal (EBPR) systems. Two of the SBRs were bioaugmented during start-up by adding pure cultures of Acinetobacter spp., the third reactor received an amendment of activated sludge from a laboratory-scale EBPR system, and the fourth reactor, receiving no amendment, served as a control. Various chemical parameters were measured to monitor the performance of the four SBRS. Oligonucleotide probes of nested phylogenetic specificity were designed to quantify the contribution of Acinetobacter to EBPR. The probes were characterized for use in quantitative membrane hybridizations and fluorescent in situ hybridizations. Data from hybridizations with samples collected from the SBRs show declining levels of Acinetobacter spp. over the experiment. All four reactors achieved significant phosphorus removal and 90% nitrification after three days of operation. The results do not show a positive correlation between levels of Acinetobacter and successful EBPR.
The Clark County Water Reclamation District (CCWRD), in Las Vegas, Nevada, operates a 100-mgd wastewater treatment plant that is one of largest biological phosphorus removal (BPR) activated sludge facilities in the world. The plant discharges into environmentally sensitive Las Vegas Wash and Lake Mead under a strict total phosphorus (TP) discharge limitation of 0.26 mg/L. This limit is currently met through a combination of BPR and conventional tertiary filtration. Recent concerns over the water quality of the Las Vegas Wash are expected to result in more stringent TP criteria in the future. Preliminary indications are that the TP limit at the planned plant buildout capacity of 130 mgd could be as low as 0.09 mg/L. Faced with the likelihood of having to meet these low limits, the District embarked on an evaluation to investigate operational strategies and new technologies capable of reliably meeting the projected low effluent limits. This evaluation investigated the following operational strategies / treatment technologies: (a) Operational strategies to improve BPR, (b) Coagulation / flocculation / sedimentation followed by conventional tertiary filtration, and (c) microfiltration. The paper presents the details of this evaluation, and should be of much interest given the proposed new stringent EPA nutrient criteria for TP.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.