Online flow cytometric monitoring of microbial water quality in a full-scale water treatment plant

The ever-increasing need for high-quality drinking and process waters, and growing public awareness about possible contamination, drive efforts for the further development of automated control of water treatment plants. For example, membrane filtration processes and reverse osmosis in particular are generally regarded as a safe barrier for inorganic, organic, and microbial contamination. Yet, to ensure the final water quality and to increase the confidence of the end-user, intensive and preferably online monitoring should be further implemented as an early-warning tool to control membrane integrity and to prevent microbial regrowth in the distributing network. In this paper, we test the applicability of flow cytometry and cytometric fingerprinting for a full-scale water treatment plant. We demonstrate in a full-scale water treatment plant that flow cytometry can be used as online monitoring tool and that changes in water quality can be observed, which are not monitored by commonly used online quality parameters. Furthermore, we illustrate with ultrafiltration that process conditions impact the flow cytometric cell counts

Increased carboxylate production in high-rate activated A-sludge by forward osmosis thickening

Domestic wastewater represents a considerable feedstock for organics but the high dilution makes their recovery typically unsuccessful. Here we investigated three routes to 10-fold concentrate the organics using Forward Osmosis (FO) (Draw solution (DS) 2.2 M MgCl2): directly on domestic wastewater, A-sludge, or secondary sludge, with the end goal of increasing volatile fatty acid (VFA) yield from subsequent 9-day fermentation tests. Forward osmosis concentrated the total COD by a factor of 8.2 ± 1.2, 10.1 ± 2.4 and 4.8 ± 0.2 with respect to the raw streams of wastewater, secondary sludge and A-sludge. The soluble fraction of the COD was concentrated up to 3.5 times in the A-sludge and 2.1 times in the secondary sludge; the result of a combined effect of the chemical action of Mg2+ (diffused from the DS) on sludge disaggregation and cell lysis, and the physical action of recirculation and air-scouring of the A-sludge in the FO-unit. The FO-concentrated A-sludge produced 445 ± 22 mg COD-VFA g-1 CODfed, which was 4.4 times higher than for the untreated A-sludge. No VFA were produced from untreated secondary sludge, but after FO-concentration 71 ± 5 mg COD-VFA g-1 CODfed could be reached. Due to the low organics in wastewater even after FO-concentration (1.08 ± 0.08 g COD L-1), no notable VFA production occurred. The combination of A-stage technology and membrane technology for dewatering and COD concentration could be a key advancement to increase VFA production from domestic wastewater, whereby at least 45% of the COD can be recovered as valuable VFA.<br/

Flow cytometric fingerprinting to assess the microbial community response to changing water quality and additives

Water is used for a very broad range of industrial applications with different water quality requirements. In all cases, the microbial water quality remains of importance as the microbial community can cause biofouling, microbial induced corrosion, odor problems, or health hazards. A close and accurate monitoring of the microbial water quality is therefore relevant for all water types used in industrial applications. Flow cytometry and additionally flow cytometric fingerprinting have been proposed before as methods to monitor the aquatic microbial communities but it remains unclear on how sensitive the fingerprinting method is for detecting quality changes in practice for different types of water. In this paper, we compared the microbial dynamics of coarsely filtered surface water, tap water, and demineralized water by challenging these waters with different concentrations and types of nutrients (C, N, and P) and additives such as corrosion inhibitors and biocides. We demonstrated that the cytometric fingerprints of the aquatic microbial communities differed in function of the type and concentration of product added, but that these differences are dependent on the type of water. Flow cytometry proved to be sensitive enough to detect subtle changes in microbial communities and to measure bacterial regrowth in different types of water. As a result, we conclude that cytometric fingerprints can be considered as indirect indicators of the physical-chemical composition of the water and a tool to monitor water biostability, as a tell-tale for minor environmental changes

Laboratory-scale simulation and real-time tracking of a microbial contamination event and subsequent shock-chlorination in drinking water

Rapid contamination of drinking water in distribution and storage systems can occur due to pressure drop, backflow, cross-connections, accidents, and bio-terrorism. Small volumes of a concentrated contaminant (e.g., wastewater) can contaminate large volumes of water in a very short time with potentially severe negative health impacts. The technical limitations of conventional, cultivation-based microbial detection methods neither allow for timely detection of such contaminations, nor for the real-time monitoring of subsequent emergency remediation measures (e.g., shock-chlorination). Here we applied a newly developed continuous, ultra high-frequency flow cytometry approach to track a rapid pollution event and subsequent disinfection of drinking water in an 80-min laboratory scale simulation. We quantified total (TCC) and intact (ICC) cell concentrations as well as flow cytometric fingerprints in parallel in real-time with two different staining methods. The ingress of wastewater was detectable almost immediately (i.e., after 0.6% volume change), significantly changing TCC, ICC, and the flow cytometric fingerprint. Shock chlorination was rapid and detected in real time, causing membrane damage in the vast majority of bacteria (i.e., drop of ICC from more than 380 cells mu l(-1) to less than 30 cells mu l(-1) within 4 min). Both of these effects as well as the final wash-in of fresh tap water followed calculated predictions well. Detailed and highly quantitative tracking of microbial dynamics at very short time scales and for different characteristics (e.g., concentration, membrane integrity) is feasible. This opens up multiple possibilities for targeted investigation of a myriad of bacterial short-term dynamics (e.g., disinfection, growth, detachment, operational changes) both in laboratory-scale research and full-scale system investigations in practice

Increased carboxylate production in high-rate activated A-sludge by forward osmosis thickening

Domestic wastewater represents a considerable feedstock for organics but the high dilution makes their recovery typically unsuccessful. Here we investigated three routes to 10-fold concentrate the organics using Forward Osmosis (FO) (Draw solution (DS) 2.2 M MgCl2): directly on domestic wastewater, A-sludge, or secondary sludge, with the end goal of increasing volatile fatty acid (VFA) yield from subsequent 9-day fermentation tests. Forward osmosis concentrated the total COD by a factor of 8.2 ± 1.2, 10.1 ± 2.4 and 4.8 ± 0.2 with respect to the raw streams of wastewater, secondary sludge and A-sludge. The soluble fraction of the COD was concentrated up to 3.5 times in the A-sludge and 2.1 times in the secondary sludge; the result of a combined effect of the chemical action of Mg2+ (diffused from the DS) on sludge disaggregation and cell lysis, and the physical action of recirculation and air-scouring of the A-sludge in the FO-unit. The FO-concentrated A-sludge produced 445 ± 22 mg COD-VFA g-1 CODfed, which was 4.4 times higher than for the untreated A-sludge. No VFA were produced from untreated secondary sludge, but after FO-concentration 71 ± 5 mg COD-VFA g-1 CODfed could be reached. Due to the low organics in wastewater even after FO-concentration (1.08 ± 0.08 g COD L-1), no notable VFA production occurred. The combination of A-stage technology and membrane technology for dewatering and COD concentration could be a key advancement to increase VFA production from domestic wastewater, whereby at least 45% of the COD can be recovered as valuable VFA.<br/

Detecting phenotypes with Raman spectroscopy

C

Abdominal aortic aneurysm is associated with a variant in low-density lipoprotein receptor-related protein 1

Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value &lt; 1 × 10-5) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p &lt; 1 × 10-5). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10-10, odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression

Genome-wide association identifies nine common variants associated with fasting proinsulin levels and provides new insights into the pathophysiology of type 2 diabetes.

OBJECTIVE: Proinsulin is a precursor of mature insulin and C-peptide. Higher circulating proinsulin levels are associated with impaired β-cell function, raised glucose levels, insulin resistance, and type 2 diabetes (T2D). Studies of the insulin processing pathway could provide new insights about T2D pathophysiology. RESEARCH DESIGN AND METHODS: We have conducted a meta-analysis of genome-wide association tests of ∼2.5 million genotyped or imputed single nucleotide polymorphisms (SNPs) and fasting proinsulin levels in 10,701 nondiabetic adults of European ancestry, with follow-up of 23 loci in up to 16,378 individuals, using additive genetic models adjusted for age, sex, fasting insulin, and study-specific covariates. RESULTS: Nine SNPs at eight loci were associated with proinsulin levels (P < 5 × 10(-8)). Two loci (LARP6 and SGSM2) have not been previously related to metabolic traits, one (MADD) has been associated with fasting glucose, one (PCSK1) has been implicated in obesity, and four (TCF7L2, SLC30A8, VPS13C/C2CD4A/B, and ARAP1, formerly CENTD2) increase T2D risk. The proinsulin-raising allele of ARAP1 was associated with a lower fasting glucose (P = 1.7 × 10(-4)), improved β-cell function (P = 1.1 × 10(-5)), and lower risk of T2D (odds ratio 0.88; P = 7.8 × 10(-6)). Notably, PCSK1 encodes the protein prohormone convertase 1/3, the first enzyme in the insulin processing pathway. A genotype score composed of the nine proinsulin-raising alleles was not associated with coronary disease in two large case-control datasets. CONCLUSIONS: We have identified nine genetic variants associated with fasting proinsulin. Our findings illuminate the biology underlying glucose homeostasis and T2D development in humans and argue against a direct role of proinsulin in coronary artery disease pathogenesis