Secondary Treated Wastewater Samples Research Articles

First environmental surveillance for the presence of SARS-CoV-2 RNA in wastewater and river water in Japan

Wastewater-based epidemiology is a powerful tool to understand the actual incidence of coronavirus disease 2019 (COVID-19) in a community because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, can be shed in the feces of infected individuals regardless of their symptoms. The present study aimed to assess the presence of SARS-CoV-2 RNA in wastewater and river water in Yamanashi Prefecture, Japan, using four quantitative and two nested PCR assays. Influent and secondary-treated (before chlorination) wastewater samples and river water samples were collected five times from a wastewater treatment plant and three times from a river, respectively, between March 17 and May 7, 2020. The wastewater and river water samples (200–5000 mL) were processed by using two different methods: the electronegative membrane-vortex (EMV) method and the membrane adsorption-direct RNA extraction method. Based on the observed concentrations of indigenous pepper mild mottle virus RNA, the EMV method was found superior to the membrane adsorption-direct RNA extraction method. SARS-CoV-2 RNA was successfully detected in one of five secondary-treated wastewater samples with a concentration of 2.4 × 103 copies/L by N_Sarbeco qPCR assay following the EMV method, with sequence confirmation of the qPCR product, whereas all the influent samples were tested negative for SARS-CoV-2 RNA. This result could be attributed to higher limit of detection for influent (4.0 × 103–8.2 × 104 copies/L) with a lower filtration volume (200 mL) compared to that for secondary-treated wastewater (1.4 × 102–2.5 × 103 copies/L) with a higher filtration volume of 5000 mL. None of the river water samples tested positive for SARS-CoV-2 RNA. Comparison with the reported COVID-19 cases in Yamanashi Prefecture showed that SARS-CoV-2 RNA was detected in the secondary-treated wastewater sample when the cases peaked in the community. This is the first study reporting the detection of SARS-CoV-2 RNA in wastewater in Japan.

Evaluation of antibacterial activity of chitosan against different bacterial strains

The present study is related to new green and low cost technical method for wastewater treatment using chitosan as natural material. Chitosan was prepared from chitin of the seafood’s shell (Procambrus clarkia). Preparation of chitosan was carried out by a chemical process involving demineralization, deproteinization and deacetylation. Chitosan is largely known for its activity against a wide range of microorganisms. Antibacterial effect of different doses of chitosan (0.09, 0.2, 0.4, 0.6 and 0.8 g) on Escherichia coli (E. coli) bacteria in the secondary treated wastewater samples was studied. The secondary treated wastewater was collected from Zenein wastewater treatment plant. Also the effectiveness of chitosan on Enterococcus faecalis, Bacillus subtillus, Staphylococcu saureus (gram +ve bacteria), Escherichia coli, Enterobacter aerogenes (gram –ve) was evaluated by the reduction in total bacterial count of each strain in synthetic media. The study was extended to measure the antibacterial activity (inhibition zone) of chitosan on E. coli by the poured plate method. The results indicated that the optimum conditions at which 99.98% removal for all types of bacteria were 0.6 g chitosan, contact time 30 min and shaking 250 rpm. According to the obtained results, the most acceptable antimicrobial mechanism is found to include the presence of charged groups in the polymer backbone and their ionic interactions with bacterial wall constituents. It could be concluded that chitosan could be used for disinfection of the secondary treated wastewater.

Reclaiming phosphorus from secondary treated municipal wastewater with engineered biochar

Phosphorus (P), a vital growth-limiting nutrient, is often lost in wastewater discharge, which may not only deteriorate water quality but also accelerate P depletion. In this study, laboratory experiments were conducted to investigate the reclamation and reuse of P from secondary treated wastewater (STWW) by engineered biochar loaded with aluminum oxyhydroxides (AlOOH). Biochar loaded with colloidal and nanosized AlOOH crystalline flakes was successfully produced through direct pyrolysis of hickory wood chips pretreated with aluminum salt. STWW samples were collected from a local wastewater treatment plant to evaluate the P sorption ability of the engineered biochar. The real wastewater was used in batch sorption experiments and the results showed that the engineered biochar effectively removed P from the STWW with relatively fast kinetics (<8 h) and good capacity (8,346 mg-P/kg), mainly through the electrostatic attraction mechanism. When the engineered biochar was packed in fixed-bed columns, it also effective removed P from the real STWW. The P removal efficiencies of the fixed-bed columns were affected by biochar dosage and flow rate. Various fixed-bed filtration models were applied to simulate the column experimental data and the model results matched the experimental breakthrough curves of P well. After the use, the engineered biochar was laden with P and thus significantly stimulated seed (Vigna radiata R. Wilczek) germination and early seedling growth. Findings from this study demonstrate that engineered biochar has promising applications in wastewater treatment because it can not only reduce P level in discharge to benefit the environment but also reclaim it as an agricultural fertilizer to improve P biogeochemical cycling and sustainability.

Comparison of methods to determine the microbial quality of alternative irrigation waters

The availability of water for crop irrigation is decreasing due to droughts, population growth, and pollution. Implementation of the Food Safety and Modernization Act (FSMA) for irrigation water standards will discourage growers to use poor microbial quality water for produce crop irrigation. We evaluated the applicability of a novel concentrator method for assessment of microbiological quality of alternative waters including secondary-treated wastewater (STWW), roof-harvest rainwater (RHW), and creek water (CW) in comparison to the standard membrane filtration method. Water samples of 100 ml were filtered through a 0.45 μm membrane filter using a vacuum manifold or concentrated to ∼250 μl using the innovative concentrator. Then they were directly enumerated on specific agars, or enriched to monitor the populations of fecal bacterial indicators (Escherichia coli, enterococci, total and fecal coliforms) and bacterial pathogens (Salmonella, Listeria monocytogenes, and E. coli O157:H7). Presumptive pathogens were confirmed by real-time quantitative PCR. In total, 25 samples of alternative water were analyzed including 7 STWW, 9 RHW, and 9 CW. No significant differences between both detection methods were observed when enumerating indicator bacterial populations and detecting the presence of pathogens in RHW and CW samples. Recovery of fecal coliforms in STWW samples by concentrator analysis was significantly lower than the membrane filtration technique. Results suggest that performance of the concentrator method is equivalent to membrane filtration method in determining the microbiological quality of CW and RHW waters; the type of the water sources may influence the accuracy and sensitivity of the concentrator analysis.

Optimizing the flocculation of powdered activated carbon in wastewater treatment by dosing iron salt in single- and two-stage processes

For the removal of anthropogenic micropollutants from wastewater, adsorption onto powdered activated carbon (PAC) is increasingly applied in wastewater treatment. To prevent desorption of adsorbed micropollutants into natural water bodies, the PAC is mostly separated from treated water by combined flocculation and filtration. While the adsorption efficiency of PAC has been thoroughly investigated in the past, no studies on its flocculation behavior and recommendations for operating large-scale PAC flocculation processes are available up to now.In this study, flocculation experiments were performed using secondary treated wastewater samples, a commercially available PAC product and an iron-based coagulant. Single- and two-stage flocculation processes were simulated in laboratory scale under variation of coagulant dosage, stirring rates and retention times in each process stage. In order to obtain real-time quantitative results, the flocculation process was continuously monitored by Focused Beam Reflectance Measurement and evaluated with regard to the reduction of a fine particle fraction sized <10μm. The flocculation kinetics were modelled by exponential curves, taking into account mass transport limitations in the first phase of the process as well as equilibria between floc growth and break-up at longer retention times. On this basis, optimum operating parameters for PAC flocculation were determined and strategies to meet fluctuating process conditions were deduced. By operating a fast mixing stage at velocity gradients of 50–90/s for 10min and, subsequently, a slow mixing stage at 20/s for 10min, the concentration of particles sized <10μm could be reduced by around 99%.

Amplicon-based profiling of bacteria in raw and secondary treated wastewater from treatment plants across Australia.

In this study, we investigated the use of Illumina high-throughput sequencing of 16S ribosomal RNA (rRNA) amplicons to explore microbial diversity and community structure in raw and secondary treated wastewater (WW) samples from four municipal wastewater treatment plants (WWTPs A-D) across Australia. Sequence reads were analyzed to determine the abundance and diversity of bacterial communities in raw and secondary treated WW samples across the four WWTPs. In addition, sequence reads were also characterized to phenotypic features and to estimate the abundance of potential pathogenic bacterial genera and antibiotic-resistant genes in total bacterial communities. The mean coverage, Shannon diversity index, observed richness (S obs), and abundance-based coverage estimate (ACE) of richness for raw and secondary treated WW samples did not differ significantly (P>0.05) among the four WWTPs examined. Generally, raw and secondary treated WW samples were dominated by members of the genera Pseudomonas, Arcobacter, and Bacteroides. Evaluation of source contributions to secondary treated WW, done using SourceTracker, revealed that 8.80-61.4% of the bacterial communities in secondary treated WW samples were attributed to raw WW. Twenty-five bacterial genera were classified as containing potential bacterial pathogens. The abundance of potentially pathogenic genera in raw WW samples was higher than that found in secondary treated WW samples. Among the pathogenic genera identified, Pseudomonas and Arcobacter had the greatest percentage of the sequence reads. The abundances of antibiotic resistance genes were generally low (<0.5%), except for genes encoding ABC transporters, which accounted for approximately 3% of inferred genes. These findings provided a comprehensive profile of bacterial communities, including potential bacterial pathogens and antibiotic-resistant genes, in raw and secondary treated WW samples from four WWTPs across Australia and demonstrated that Illumina high-throughput sequencing can be an alternative approach for monitoring WW quality in order to protect environmental and human health.

Advanced oxidative degradation of bisphenol A and bisphenol S

In this study, the degradation of two emerging contaminants, bisphenol A (BPA) and bisphenol S (BPS), in spiked water and secondary treated waste water samples were investigated using four different oxidation methods: ultraviolet C (UVC) (254 nm), UVC/hydrogen peroxide (H2O2), ozone (O3) and ultraviolet A (UVA)/ozone (365 nm). Investigation of the effect of light intensity on the rate constants of UVC and UVC/hydrogen peroxide processes and identification of intermediates in the degradation process were conducted. The highest degradation rates were achieved for the UVA/ozone process with k values of 2·2 or 1·9 min−1 in secondary treated waste water (absorbance at 254 nm = 0·164 AU). Based on the results, the fate of BPA and BPS in municipal waste water as they move through the UV (254 nm) disinfection unit of a local waste water treatment plant in Calgary, Canada, was evaluated. It was concluded that in the UV disinfection unit, only 1% and 6% of BPA and BPS were degraded respectively. However, should 0·042 M hydrogen peroxide be added to the waste water stream entering the disinfection unit, 56% of BPA and 47% of BPS can be degraded. By implementation of ozone and UVA/ozone processes, degradation levels could exceed &gt;95%.

Quantitative real-time PCR analysis of total and propidium monoazide-resistant fecal indicator bacteria in wastewater

A real-time quantitative PCR (qPCR) method and a modification of this method incorporating pretreatment of samples with propidium monoazide (PMA) were evaluated for respective analyses of total and presumptively viable Enterococcus and Bacteroidales fecal indicator bacteria. These methods were used in the analyses of wastewater samples to investigate their feasibility as alternatives to current fecal indicator bacteria culture methods for predicting the efficiency of viral pathogen removal by standard treatment processes. PMA treatment was effective in preventing qPCR detection of target sequences from non-viable cells. Concentrates of small volume, secondary-treated wastewater samples, collected from a publicly owned treatment works (POTW) under normal operating conditions, had little influence on this effectiveness. Higher levels of total suspended solids, such as those associated with normal primary treatment and all treatment stages during storm flow events, appeared to interfere with PMA effectiveness under the sample preparation conditions employed. During normal operating conditions at three different POTWs, greater reductions were observed in PMA-qPCR detectable target sequences of both Enterococcus and Bacteroidales than in total qPCR detectable sequences. These reductions were not as great as those observed for cultivable fecal indicator bacteria in response to wastewater disinfection. Reductions of PMA-qPCR as well as total qPCR detectable target sequences from enterococci and, to a lesser extent, Bacteroidales correlated well with reductions in infectious viruses during both normal and storm flow operating conditions and therefore may have predictive value in determining the efficiency at which these pathogens are removed.