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Results 1 - 20 de 621
1.

Evaluating the efficiency of carbon utilisation via bioenergetics between biological aerobic and denitrifying phosphorus removal systems.

PLoS One; 12(10): e0187007, 2017.
Article in English | MEDLINE | ID: mdl-29065157

ABSTRACT

There are two biological systems available for removing phosphorus from waste water, conventional phosphorus removal (CPR) and denitrifying phosphorus removal (DPR) systems, and each is characterized by the type of sludge used in the process. In this study, we compared the characteristics associated with the efficiency of carbon utilization between CPR and DPR sludge using acetate as a carbon source. For DPR sludge, the heat emitted during the phosphorus release and phosphorus uptake processes were 45.79 kJ/mol e- and 84.09 kJ/mol e-, respectively. These values were about 2 fold higher than the corresponding values obtained for CPR sludge, suggesting that much of the energy obtained from the carbon source was emitted as heat. Further study revealed a smaller microbial mass within the DPR sludge compared to CPR sludge, as shown by a lower sludge yield coefficient (0.05 gVSS/g COD versus 0.36 gVSS/g COD), a result that was due to the lower energy capturing efficiency of DPR sludge according to bioenergetic analysis. Although the efficiency of anoxic phosphorus removal was only 39% the efficiency of aerobic phosphorus removal, the consumption of carbon by DPR sludge was reduced by 27.8% compared to CPR sludge through the coupling of denitrification with dephosphatation.
2.

Constructed wetlands and solar-driven disinfection technologies for sustainable wastewater treatment and reclamation in rural India: SWINGS project.

Water Sci Technol; 76(6): 1474-1489, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28953474

ABSTRACT

SWINGS was a cooperation project between the European Union and India, aiming at implementing state of the art low-cost technologies for the treatment and reuse of domestic wastewater in rural areas of India. The largest wastewater treatment plant consists of a high-rate anaerobic system, followed by vertical and horizontal subsurface flow constructed wetlands with a treatment area of around 1,900 m and a final step consisting of solar-driven anodic oxidation (AO) and ultraviolet (UV) disinfection units allowing direct reuse of the treated water. The implementation and operation of two pilot plants in north (Aligarh Muslim University, AMU) and central India (Indira Gandhi National Tribal University, IGNTU) are shown in this study. The overall performance of AMU pilot plant during the first 7 months of operation showed organic matter removal efficiencies of 87% total suspended solids, 95% 5-day biological oxygen demand (BOD ) and 90% chemical oxygen demand, while Kjeldahl nitrogen removal reached 89%. The UV disinfection unit produces water for irrigation and toilet flushing with pathogenic indicator bacteria well below WHO guidelines. On the other hand, the AO disinfection unit implemented at IGNTU and operated for almost a year has been shown to produce an effluent of sufficient quality to be reused by the local population for agriculture and irrigation.
3.

Greenlandic water and sanitation-a context oriented analysis of system challenges towards local sustainable development.

Article in English | MEDLINE | ID: mdl-28849342

ABSTRACT

Today, as Greenland focuses on more economic and cultural autonomy, the continued development of societal infrastructure systems is vital. At the same time, pressure is put on the systems by a lack of financial resources and locally based professional competences as well as new market-based forms of organization. Against this background, the article discusses the challenges facing Greenland's self-rule in relation to further develop the existing water and wastewater systems so that they can contribute to the sustainable development of Greenland. The article reviews the historical development of the water supply and wastewater system. This leads to an analysis of the sectorisation, which in recent decades has reorganized the Greenlandic infrastructures, and of how this process is influencing local sustainable development. The article discusses the socio-economic and human impacts and points to the need for developing the water and sanitation system to support not only hygiene and health, but also local sustainable development.
4.

Estimation of the removal efficiency of heavy metals and nutrients from ecological drainage ditches treating town sewage during dry and wet seasons.

Environ Monit Assess; 189(9): 434, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28779427

ABSTRACT

Vegetated drainage ditches (ecological drainage ditches, EDD) are commonly used for the treatment of nutrients, suspended solids, and pesticides, from agricultural lands and aquaculture effluent. However, their effectiveness to remove heavy metals/metalloids (HM/Ms) and fate remains largely unexplored. In addition, there exists some uncertainty concerning the performance of the EDD in treating HM/Ms. This study presents a thorough assessment on the removal efficiencies of HM/Ms and identifies the parameters affecting the HM/Ms removal process in the EDD receiving primary domestic sewage for 13 years. The mean concentrations of the studied HM/Ms in sediments were lower than those reported in the aquatic ecosystems affected by coal-mine drainage and industrial wastewaters. The results also showed that the concentrations of the selected HM/Ms in ditch sediment were generally far higher than the soil background values of Sichuan basin. Concentrations of all the studied HM/Ms and nutrients in water entering the EDD were significantly higher than the effluent. The annual mean removal efficiencies of Ni, Cu, Cr, Zn, Cd, Pb, As, Fe, Al, Mn, N, and P in the ecological drainage ditch were 50.6, 56.1, 63.3, 79.3, 67.5, 80.1, 60.3, 52.6, 19.8, 24.3, 72.0, and 59.7%, respectively. The study also displayed that dissolved oxygen levels at the outlet were significantly (p < 0.001) higher after passing into the EDD system. The pH was kept at neutral or alkaline. Removal of HM/Ms and nutrients was seasonal, generally peaking in the growing season. Sedimentation was the major mechanism removing HM/Ms within the EDD system. EDD was found to possess a favorable influence at mitigating HM/Ms and nutrients in situ and can be successfully utilized to resolve this type of environmental pollution.
5.

Piloting water quality testing coupled with a national socioeconomic survey in Yogyakarta province, Indonesia, towards tracking of Sustainable Development Goal 6.

Int J Hyg Environ Health; 220(7): 1141-1151, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28743592

ABSTRACT

There remains a pressing need for systematic water quality monitoring strategies to assess drinking water safety and to track progress towards the Sustainable Development Goals (SDG). This study incorporated water quality testing into an existing national socioeconomic survey in Yogyakarta province, Indonesia; the first such study in Indonesia in terms of SDG tracking. Multivariate regression analysis assessed the association between faecal and nitrate contamination and drinking water sources household drinking water adjusted for wealth, education level, type of water sources and type of sanitation facilities. The survey observed widespread faecal contamination in both sources for drinking water (89.2%, 95%CI: 86.9-91.5%; n=720) and household drinking water (67.1%, 95%CI: 64.1-70.1%; n=917) as measured by Escherichia coli. This was despite widespread improved drinking water source coverage (85.3%) and commonly self-reported boiling practices (82.2%). E.coli concentration levels in household drinking water were associated with wealth, education levels of a household head, and type of water source (i.e. vender water or local sources). Following the proposed SDG definition for Target 6.1 (water) and 6.2 (sanitation), the estimated proportion of households with access to safely managed drinking water and sanitation was 8.5% and 45.5%, respectively in the study areas, indicating substantial difference from improved drinking water (82.2%) and improved sanitation coverage (70.9%) as per the MDGs targets. The greatest contamination and risk factors were found in the poorest households indicating the urgent need for targeted and effective interventions here. There is suggested evidence that sub-surface leaching from on-site sanitation adversely impacts on drinking water sources, which underscores the need for further technical assistance in promoting latrine construction. Urgent action is still needed to strengthen systematic monitoring efforts towards tracking SDG Goal 6.
6.

Effect of reflux ratio on nitrogen removal in a novel upflow microaerobic sludge reactor treating piggery wastewater with high ammonium and low COD/TN ratio: Efficiency and quantitative molecular mechanism.

Bioresour Technol; 243: 922-931, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28738547

ABSTRACT

A novel upflow microaerobic sludge reactor (UMSR) was constructed to treat manure-free piggery wastewater with high NH -N and low COD/TN ratio. In the light of the potential effect of effluent reflux ratio (RR) on nitrogen removal, performance of the UMSR was evaluated at 35°C and hydraulic retention time 8h with RR decreased from 45 to 25 by stages. A COD, NH -N and TN removal of above 77.1%, 80.0% and 86.6%, respectively, was kept with a RR over 35. To get an effluent of TN not more than 80mg/L with a TN load removal above 0.88kg/(m ·d), the RR should be at least 34. Real-time quantitative polymerase chain reaction of functional bacteria revealed that the RR of less than 34 stimulated ammonium oxidation but badly inhibited anammox, the dominant nitrogen removal pathway, resulting in the remarkable decrease of nitrogen removal in the reactor.
7.

Consumer Perceptions of the Safety of Ready-to-Eat Foods in Retail Food Store Settings.

J Food Prot; 80(8): 1364-1377, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28722484

ABSTRACT

To better understand how consumers perceive food safety risks in retail food store settings, a survey was administered to 1,041 nationally representative participants who evaluated possible food safety risks depicted in selected photographs and self-reported their perceptions, attitudes, and behaviors. Participants were shown 12 photographs taken at retail stores portraying either commonly perceived or actual food safety contributing factors, such as cross-contamination, product and equipment temperatures, worker hygiene, and/or store sanitation practices. Participants were then asked to specifically identify what they saw, comment as to whether what they saw was safe or unsafe, and articulate what actions they would take in response to these situations. In addition to the survey, focus groups were employed to supplement survey findings with qualitative data. Survey respondents identified risk factors for six of nine actual contributing factor photographs >50% of the time: poor produce storage sanitation (86%, n = 899), cross-contamination during meat slicing (72%, n = 750), bare-hand contact of ready-to-eat food in the deli area (67%, n = 698), separation of raw and ready-to-eat food in the seafood case (63%, n = 660), cross-contamination from serving utensils in the deli case (62%, n = 644), and incorrect product storage temperature (51%, n = 528). On a scale of 1 to 5, where 1 was very unsafe and 5 was very safe, a significant difference was found between average risk perception scores for photographs of actual contributing factors (score of ca. 2.5) and scores for photographs of perceived contributing factors (score of ca. 2.0). Themes from the focus groups supported the results of the survey and provided additional insight into consumer food safety risk perceptions. The results of this study inform communication interventions for consumers and retail food safety professionals aimed at improving hazard identification.
8.

Enabling the sustainable Faecal Sludge Management service delivery chain-A case study of dense settlements in Kigali, Rwanda.

Int J Hyg Environ Health; 220(6): 960-973, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28596087

ABSTRACT

The lack of access to basic sanitation is a global concern and alarmingly prevalent in low- and middle- income countries. In the densely populated settlements of these countries, on-site sanitation systems are usually the only feasible option because dwellers there have no sewers in place to connect to. Using on-site sanitation facilities results in an accumulation of faecal sludge which needs to be properly managed to ensure the well-being of the users as well as the surrounding environment. Unfortunately, often the conditions for faecal sludge management (FSM) within dense settlements are adverse and thus hamper sustainable FSM. We use the normative framework of the FSM enabling environment to gather empirical evidence from densely populated settlements of Kigali city in Rwanda to examine current FSM practices and the extent to which these are being influenced and affected by the setting within which they are taking place. The analysis of the study findings confirms that the existing conditions for FSM in these settlements are inadequate. The specific constraints that hinder the achievement of sustainable FSM include limited government focus on the sanitation sector, high turnover of staff in relevant government institutions, pit sludge management is not placed on the sanitation projects agenda, the existing relevant bylaws are not pro-poor oriented, a lack of clear responsibilities, a lack of relevant local professional training opportunities, unaffordability of FSM services and an inhibition to discuss FSM. Drawing on the involved stakeholders' own perceptions and suggestions, we identify possible approaches to overcome the identified constraints and to allow all actors in the FSM chain to contribute effectively to the management of faecal sludge in densely populated low-income urban settlements. Finally, our study also presents a contribution to the theoretical conceptualisation of the enabling environment for sustainable FSM.
9.

Novel Stokesian Metrics that Quantify Collision Efficiency, Floc Strength, and Discrete Settling Behavior.

Water Environ Res; 89(7): 586-597, 2017 Jul 01.
Article in English | MEDLINE | ID: mdl-28641670

ABSTRACT

Novel parameters were developed to predict the effluent quality and settling behavior in clarifiers that cannot conventionally be achieved using either the conventional flux theory or overflow rates. Simple batch experiments based on the critical settling velocity (CSV) selection were used as the basis for the development of three novel parameters: intrinsic settling classes (ISC), threshold of flocculation/flocculation limitation (TOF/α), and floc strength. ISC was proven to accurately (±2%) determine the granule fraction and discrete particle distribution. TOF quantified the minimum solids concentration needed to form large flocs and was directly linked to collision efficiency. In hybrid systems, an exponential fitting on a CSV matrix was proposed to quantify the collision efficiency of flocs (α). Shear studies were conducted to quantify floc strength. The methods were applied to a wide spectrum of sludge types to show the broad applicability and sensitivity of the novel methods.
10.

Sustainable pyrolytic sludge-char preparation on improvement of closed-loop sewage sludge treatment: Characterization and combined in-situ application.

Chemosphere; 184: 1043-1053, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28662548

ABSTRACT

Aiming at closed-loop sustainable sewage sludge treatment, an optimal and economical pyrolytic temperature was found at 400-450 °C considering its pyrolysis efficiency of 65%, fast cracking of hydrocarbons, proteins and lipids and development of aromatized porous structure. Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) tests demonstrated the development of adsorptive functional groups and crystallographic phases of adsorptive minerals. The optimal sludge-char, with a medium specific surface area of 39.6 m g and an iodine number of 327 mgI g , performed low heavy metals lixiviation. The application of sludge-char in raw sewage could remove 30% of soluble chemical oxygen demand (SCOD), along with an acetic acid adsorption capacity of 18.0 mg g . The developed mesopore and/or macropore structures, containing rich acidic and basic functional groups, led to good biofilm matrices for enhanced microbial activities and improved autotrophic nitrification in anoxic stage of an A/O reactor through adsorbed extra carbon source, and hence achieved the total nitrogen (TN) removal up to 50.3%. It is demonstrated that the closed-loop sewage sludge treatment that incorporates pyrolytic sludge-char into in-situ biological sewage treatment can be a promising sustainable strategy by further optimization.
11.

Examining the safety of menstrual cups among rural primary school girls in western Kenya: observational studies nested in a randomised controlled feasibility study.

BMJ Open; 7(4): e015429, 2017 May 04.
Article in English | MEDLINE | ID: mdl-28473520

ABSTRACT

OBJECTIVE: Examine the safety of menstrual cups against sanitary pads and usual practice in Kenyan schoolgirls. DESIGN: Observational studies nested in a cluster randomised controlled feasibility study. SETTING: 30 primary schools in a health and demographic surveillance system in rural western Kenya. PARTICIPANTS: Menstruating primary schoolgirls aged 14-16 years participating in a menstrual feasibility study. INTERVENTIONS: Insertable menstrual cup, monthly sanitary pads or 'usual practice' (controls). OUTCOME MEASURES: vaginal colonization, growth on sampled used cups, toxic shock syndrome or other adverse health outcomes. RESULTS: Among 604 eligible girls tested, no adverse event or TSS was detected over a median 10.9 months follow-up. prevalence was 10.8%, with no significant difference over intervention time or between groups. Of 65 positives at first test, 49 girls were retested and 10 (20.4%) remained positive. Of these, two (20%) sample isolates tested positive for toxic shock syndrome toxin-1; both girls were provided pads and were clinically healthy. Seven per cent of cups required replacements for loss, damage, dropping in a latrine or a poor fit. Of 30 used cups processed for growth, 13 (37.1%, 95% CI 21.1% to 53.1%) had growth. growth was greatest in newer compared with established users (53%vs22.2%, p=0.12). CONCLUSIONS: Among this feasibility sample, no evidence emerged to indicate menstrual cups are hazardous or cause health harms among rural Kenyan schoolgirls, but large-scale trials and post-marketing surveillance should continue to evaluate cup safety.
12.

A high-efficiency denitrification bioreactor for the treatment of acrylonitrile wastewater using waterborne polyurethane immobilized activated sludge.

Bioresour Technol; 239: 472-481, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28544987

ABSTRACT

The performance of a laboratory-scale, high-efficiency denitrification bioreactor (15L) using activated sludge immobilized by waterborne polyurethane in treating acrylonitrile wastewater with high concentration of nitrate nitrogen (249mg/L) was investigated. The bioreactor was operated at 30°C for 220days. Batch denitrification experiments showed that the optimal operation parameters were C/NO -N molar ratio of 2.0 using sodium acetate as electron donor and carrier filling rate of 20% (V/V) in the bioreactor. Stable performance of denitrification was observed with a hydraulic retention time of 30 to 38h. A volumetric removal rate up to 2.1kgN/m ·d was achieved with a total nitrogen removal efficiency of 95%. Pyrosequencing results showed that Rhodocyclaceae and Pseudomonadaceae were the dominant bacterial families in the immobilized carrier and bioreactor effluent. The overall microbial diversity declined as denitrifiers gradually dominated and the relative abundance of other bacteria decreased along with testing time.
13.

Stepwise hydrolysis to improve carbon releasing efficiency from sludge.

Water Res; 119: 225-233, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28463770

ABSTRACT

Based on thermal alkaline hydrolysis (TAH), a novel strategy of stepwise hydrolysis was developed to improve carbon releasing efficiency from waste activated sludge (WAS). By stepwise increasing hydrolysis intensity, conventional sludge hydrolysis (the control) was divided into four stages for separately recovering sludge carbon sources with different bonding strengths, namely stage 1 (60 °C, pH 6.0-8.0), stage 2 (80 °C, pH 6.0-8.0), stage 3 (80 °C, pH 10.0) and stage 4 (90 °C, pH 12.0). Results indicate stepwise hydrolysis could enhance the amount of released soluble chemical oxygen demand (SCOD) for almost 2 times, from 7200 to 14,693 mg/L, and the released carbon presented better biodegradability, with BOD/COD of 0.47 and volatile fatty acids (VFAs) yield of 0.37 g VFAs/g SCOD via anaerobic fermentation. Moreover, stepwise hydrolysis also improved the dewaterability of hydrolyzed sludge, capillary suction time (CST) reducing from 2500 to 1600 s. Economic assessment indicates stepwise hydrolysis shows less alkali demand and lower thermal energy consumption than those of the control. Furthermore, results of this study help support the concepts of improving carbon recovery in wastewater by manipulating WAS composition and the idea of classifiably recovering the nutrients in WAS.
14.

Efficiency of an upflow anaerobic sludge blanket reactor treating potato starch processing wastewater and related process kinetics, functional microbial community and sludge morphology.

Bioresour Technol; 239: 105-116, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28501683

ABSTRACT

Herein, an upflow anaerobic sludge blanket reactor was employed to treat potato starch processing wastewater and the efficacy, kinetics, microbial diversity and morphology of sludge granules were investigated. When organic loading rate (OLR) ranging from 2.70 to 13.27kgCOD/m .d was implemented with various hydraulic retention times (72h, 48h and 36h), COD removal could reach 92.0-97.7%. Highest COD removal (97.7%) was noticed when OLR was 3.65kgCOD/m .d, but had declined to 92.0% when OLR was elevated to 13.27kgCOD/m .d. Methane and biogas production increased from 0.48 to 2.97L/L.d and 0.90 to 4.28L/L.d, respectively. Kinetics and predictions by modified-Gompertz model agreed better with experimental data as opposed to first-order kinetic model. Functional population with highest abundance was Chloroflexi (28.91%) followed by Euryarchaeota (22.13%), Firmicutes (16.7%), Proteobacteria (16.25%) and Bacteroidetes (7.73%). Compared with top sludge, tightly-bound extracellular polymeric substances was high within bottom and middle sludge. Morphology was predominantly Methanosaeta-like cells, Methanosarcina-like cells, rods and cocci colonies.
15.

Bacteriophage removal efficiency as a validation and operational monitoring tool for virus reduction in wastewater reclamation: Review.

Water Res; 121: 258-269, 2017 Sep 15.
Article in English | MEDLINE | ID: mdl-28551509

ABSTRACT

The multiple-barrier concept is widely employed in international and domestic guidelines for wastewater reclamation and reuse for microbiological risk management, in which a wastewater reclamation system is designed to achieve guideline values of the performance target of microbe reduction. Enteric viruses are one of the pathogens for which the target reduction values are stipulated in guidelines, but frequent monitoring to validate human virus removal efficacy is challenging in a daily operation due to the cumbersome procedures for virus quantification in wastewater. Bacteriophages have been the first choice surrogate for this task, because of the well-characterized nature of strains and the presence of established protocols for quantification. Here, we performed a meta-analysis to calculate the average log reduction values (LRVs) of somatic coliphages, F-specific phages, MS2 coliphage and T4 phage by membrane bioreactor, activated sludge, constructed wetlands, pond systems, microfiltration and ultrafiltration. The calculated LRVs of bacteriophages were then compared with reported human enteric virus LRVs. MS2 coliphage LRVs in MBR processes were shown to be lower than those of norovirus GII and enterovirus, suggesting it as a possible validation and operational monitoring tool. The other bacteriophages provided higher LRVs compared to human viruses. The data sets on LRVs of human viruses and bacteriophages are scarce except for MBR and conventional activated sludge processes, which highlights the necessity of investigating LRVs of human viruses and bacteriophages in multiple treatment unit processes.
16.

Associating liver partition and portal vein ligation for bleeding hepatocellular carcinoma in HBV cirrhosis: a safety strategy.

Article in English | MEDLINE | ID: mdl-28447055

ABSTRACT

The incidence of hepatocellular carcinoma (HCC) spontaneous tumor rupture varies between 3% and 26%. For resectable HCC ruptures, emergency hepatectomy or staged hepatectomy after transcatheter arterial embolization (TAE) are life-saving procedures, and efficient therapeutic methods. We report a multimodal therapy including TAE, associating liver partition and portal vein ligation (ALPPS) and immunoglobuline infusion for a huge bleeding HCC with portal vein tumor thrombosis (PVTT) in hepatitis B virus (HBV) cirrhosis. ALPPS first step began with an abdominal toilette due to the massive hemoperitoneum and a portal vein incision at the bifurcation of the right and left portal veins was performed. A freely floating left part of the thrombus was extracted from the left portal vein in order to restore the left portal vein. The right portal vein with complete thrombosis was closed. Liver partition was then performed. The second step was performed without complications. A HCC Edmondson grade 4 (pT3b) and a cirrhotic liver parenchyma were described. Postoperative ascites decompensation was treated and patient was discharged in postoperative day 21. The reported triple strategy allowed us to prolong patient live. A multimodal therapy including TAE, ALPPS and immunoglobuline is a good option for a life treatment in case of huge bleeding hepatocellular carcinoma with PVTT in HBV cirrhosis.
17.

Profiles and removal efficiency of polycyclic aromatic hydrocarbons by two different types of sewage treatment plants in Hong Kong.

J Environ Sci (China); 53: 196-206, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28372744

ABSTRACT

Sewage discharge could be a major source of polycyclic aromatic hydrocarbons (PAHs) in the coastal waters. Stonecutters Island and Shatin Sewage Treatment Works (SCISTW and STSTW) in Hong Kong, adopted chemically enhanced primary treatment and biological treatment, respectively. This study aimed at (1) determining the removal efficiencies of PAHs, (2) comparing the capabilities in removing PAHs, and (3) characterizing the profile of each individual PAHs, in the two sewage treatment plants (STPs). Quantification of 16 PAHs was conducted by a Gas Chromatography. The concentrations of total PAHs decreased gradually along the treatment processes (from 301±255 and 307±217ng/L to 14.9±12.1 and 63.3±54.1ng/L in STSTW and SCISTW, respectively). It was noted that STSTW was more capable in removing total PAHs than SCISTW with average total removal efficiency 94.4%±4.12% vs. 79.2%±7.48% (p<0.05). The removal of PAHs was probably due to sorption in particular matter, confirmed by the higher distribution coefficient of individual and total PAHs in solid samples (dewatered sludge contained 92.5% and 74.7% of total PAHs in SCISTW and STSTW, respectively) than liquid samples (final effluent-total contained 7.53% and 25.3% of total PAHs in STSTW and SCISTW, respectively). Despite the impressive capability of STSTW and SCISTW in removing PAHs, there was still a considerable amount of total PAHs (1.85 and 39.3kg/year, respectively for the two STPs) being discharged into Hong Kong coastal waters, which would be an environmental concern.
18.

Division of methods for counting helminths' eggs and the problem of efficiency of these methods.

Ann Agric Environ Med; 24(1): 1-7, 2017 Mar 21.
Article in English | MEDLINE | ID: mdl-28378963

ABSTRACT

From the sanitary and epidemiological aspects, information concerning the developmental forms of intestinal parasites, especially the eggs of helminths present in our environment in: water, soil, sandpits, sewage sludge, crops watered with wastewater are very important. The methods described in the relevant literature may be classified in various ways, primarily according to the methodology of the preparation of samples from environmental matrices prepared for analysis, and the sole methods of counting and chambers/instruments used for this purpose. In addition, there is a possibility to perform the classification of the research methods analyzed from the aspect of the method and time of identification of the individuals counted, or the necessity for staining them. Standard methods for identification of helminths' eggs from environmental matrices are usually characterized by low efficiency, i.e. from 30% to approximately 80%. The efficiency of the method applied may be measured in a dual way, either by using the method of internal standard or the 'Split/Spike' method. While measuring simultaneously in an examined object the efficiency of the method and the number of eggs, the 'actual' number of eggs may be calculated by multiplying the obtained value of the discovered eggs of helminths by inverse efficiency.
19.

Municipal wastewater sludge as a sustainable bioresource in the United States.

J Environ Manage; 197: 673-680, 2017 Jul 15.
Article in English | MEDLINE | ID: mdl-28433683

ABSTRACT

Within the United States and Puerto Rico, publicly owned treatment works (POTWs) process 130.5 Gl/d (34.5 Bgal/d) of wastewater, producing sludge as a waste product. Emerging technologies offer novel waste-to-energy pathways through whole sludge conversion into biofuels. Assessing the feasibility, scalability and tradeoffs of various energy conversion pathways is difficult in the absence of highly spatially resolved estimates of sludge production. In this study, average wastewater solids concentrations and removal rates, and site specific daily average influent flow are used to estimate site specific annual sludge production on a dry weight basis for >15,000 POTWs. Current beneficial uses, regional production hotspots and feedstock aggregation potential are also assessed. Analyses indicate 1) POTWs capture 12.56 Tg/y (13.84 MT/y) of dry solids; 2) 50% are not beneficially utilized, and 3) POTWs can support seven regions that aggregate >910 Mg/d (1000 T/d) of sludge within a travel distance of 100 km.
20.

Removal of hydrogen sulfide generated during anaerobic treatment of sulfate-laden wastewater using biochar: Evaluation of efficiency and mechanisms.

Bioresour Technol; 234: 115-121, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28319759

ABSTRACT

Removal of hydrogen sulfide (H S) from biogas was investigated in a biochar column integrated with a bench-scale continuous-stirred tank reactor (CSTR) treating sulfate-laden wastewater. Synthetic wastewater containing sulfate concentrations of 200-2000mg SO /L was used as substrate, and the CSTR was operated at an organic loading rate of 1.5g chemical oxygen demand (COD)/L·day and a hydraulic retention time (HRT) of 20days. The biochar was able to remove about 98.0 (±1.2)% of H S for the ranges of concentrations from 105-1020ppmv, especially at high moisture content (80-85%). Very high H S adsorption capacity (up to 273.2±1.9mg H S/g) of biochar is expected to enhance the H S oxidation into S and sulfate. These findings bring a potentially novel application of sulfur-rich biochar as a source of sulfur, an essential but often deficient micro-nutrient in soils.
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