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1.
Washington, D.C.; PAHO; 2020-05-12.
in English | PAHO-IRIS | ID: phr-52121

ABSTRACT

Perspectives and Contributions of Nursing to the Promotion of Universal Health highlights more than 40 projects, activities, stories, and case studies received from the countries of the Region, illustrating the role of nurses and midwives in advancing toward universal health. It also details these essential health workers' rich contribution to health systems, universities, prisons, communities, governments, and schools in all the countries of the Americas. An epilogue includes a powerful story of two American nurses on the front lines of the COVID-19 epidemic. It is further proof of the vital role these health workers have in advancing health for all.


Subject(s)
Nursing , Universal Access to Health Care Services , Universal Health Coverage , Nurses , Universal Health Care , Pandemics , Coronavirus Infections , Coronavirus
2.
Bioresour Technol ; 308: 123250, 2020 Jul.
Article in English | MEDLINE | ID: mdl-32244132

ABSTRACT

This work investigated the effect of biochar addition to mitigate VFA accumulation and enhance methane production in mesophilic food waste/sludge co-digestion. Different types of biochar derived from agricultural and forestry residues at two pyrolysis temperatures were tested. Results showed that wheat straw biochar 550 °C supported the highest specific methane yield of 381.9 LCH4/kg VSadded and VS removal efficiency of 41.62% among all treatments. Degradation of propionic acid and long-chain fatty acids such as valeric, caproic and isovaleric acids was observed. This also corresponded to an increase in methanogenic favorable substrates including acetic acid (>40%) and butyric acid (~20%) over the control. Consequently, a 24% increase in overall methane production was obtained as compared to control. This demonstrated that biochar addition had positive effects on VFA degradation and methane production which could be a useful strategy to increase the organic loading in co-digestions without the fear of process failure.


Subject(s)
Refuse Disposal , Sewage , Anaerobiosis , Bioreactors , Charcoal , Fatty Acids, Volatile , Food , Methane
3.
Article in English | MEDLINE | ID: mdl-32244287

ABSTRACT

Good hand hygiene is necessary to control and prevent infections, but many children do not adequately wash their hands. While there are classroom communications targeted at children, the toilet space, the location of many hand hygiene activities, is neglected. This paper describes an initial evaluation of "123" persuasive space graphics (images and messages integrated within an architectural environment that encourage specific actions). The effectiveness (whether hand hygiene improves) and efficiency (the ease with which a setting can adopt and implement an intervention) is evaluated in three UK schools and one museum. Five evaluations (participant demographic, handwashing frequency, handwashing quality, design persuasiveness, stakeholder views) were conducted. In the school settings, persuasive space graphics increased the quality and frequency of handwashing. In the museum setting, frequency of handwashing slightly increased. In all settings children found the graphics persuasive, and stakeholders also believed them to be effective. Stakeholders considered persuasive space graphics a low-cost and time-efficient way to communicate. It can be concluded that persuasive space graphics are effective in increasing hand hygiene, particularly in school settings where children have a longer exposure to the graphics. Persuasive space graphics are also an efficient low-cost means of communicating hand hygiene.

4.
Article in English | MEDLINE | ID: mdl-32294881

ABSTRACT

Diarrhoeal disease in children under five in low income settings has been associated with multiple environmental exposure pathways, including complementary foods. Conducted from February to December 2018 in rural Malawi, this before and after trial with a control used diarrhoeal disease as a primary outcome, to measure the impact of a food hygiene intervention (food hygiene + handwashing) relative to a food hygiene and water, sanitation and hygiene (WASH) intervention (food hygiene + handwashing + faeces management + water management). The 31-week intervention was delivered by community-based coordinators through community events (n = 2), cluster group meetings (n = 17) and household visits (n = 14). Diarrhoeal disease was self-reported and measured through an end line survey, and daily diaries completed by caregivers. Difference-in-differences results show a 13-percentage point reduction in self-reported diarrhoea compared to the control group. There were also significant increases in the presence of proxy measures in each of the treatment groups (e.g., the presence of soap). We conclude that food hygiene interventions (including hand washing with soap) can significantly reduce diarrhoeal disease prevalence in children under five years in a low-income setting. Therefore, the promotion of food hygiene practices using a behaviour-centred approach should be embedded in nutrition and WASH policies and programming.

5.
Water Res ; 176: 115763, 2020 Jun 01.
Article in English | MEDLINE | ID: mdl-32272323

ABSTRACT

Kitchen wastes (KW) have been widely investigated for bio-ethanol production, while no study utilizes KW as ethanol source to stimulate the methanogenic communities to perform direct interspecies electron transfer (DIET), since the excess acidity contained after the biological ethanol-type fermentation pretreatment (BEFP) can seriously inhibit the DIET-based syntrophic metabolism. In this study, a strategy that utilized waste activated sludge (WAS) as co-substrate to relieve the excess acidity after BEFP during anaerobic co-digestion (AcoD) was proposed. The results showed that, under the mixed ratio of 1:2 and 1:5 (KW:WAS, volume ratio), both methane production and organic compound removal evidently increased, compared with that treating the sole WAS. Conversely, under the other mixed ratios (sole KW, 5:1, 2:1 and 1:1), no methane but the evident hydrogen production was detected, and syntrophic metabolism of organic acids and alcohols was prevented. Three-dimensional excitation emission matrix (3D-EEM) analysis showed that the protein-like organic compounds contained in both KW and WAS were effectively degraded. Furthermore, the maximum methane production potential from WAS during AcoD (260.5 ± 4.1 and 264.3 ± 2.7 mL/g-COD) was higher than that treating sole WAS (250.8 ± 0.1 mL/g-COD). Microbial community analysis showed that, some genera capable of metabolizing the complex organic compounds with the reduction of the elemental sulfur or equipped with the electrically conductive pili were specially enriched during AcoD under the mixed ratio of 1:2 and 1:5. They might proceed DIET with methanogens, such as Methanosarcina and Methanospirillum species, to maintain the syntrophic metabolism effective and stable, since the abundance of both Methanosarcina and Methanospirillum species evidently increased.


Subject(s)
Ethanol , Sewage , Anaerobiosis , Bioreactors , Electrons , Methane
6.
PLoS One ; 15(3): e0229666, 2020.
Article in English | MEDLINE | ID: mdl-32130241

ABSTRACT

BACKGROUND: Despite increasing political will to achieve Universal Health Coverage (UHC), there is a paucity of empiric data describing what health system indicators are useful surrogates of country-level progress towards UHC. We sought to determine what public health interventions were useful tracers of country-level UHC progress. METHODS: Across 183 countries we evaluated the extent to which 16 service delivery indicators explained variability in the UHC Service Coverage Index, (UHC SCI) a WHO-validated indicator of country-level health coverage. Dominance analyses, stratifying countries by World Bank income criteria, were used to determine which indicators were most important in in predicting UHC SCI scores. FINDINGS: Health workforce density ranked first overall, provision of basic sanitation and access to clean water ranked second, and provision of basic antenatal services ranked third. In analysis stratified by World Bank income criteria, health workforce density ranked first in Lower Middle Income-Countries (LMICs) (n = 45) and third in Upper Middle Income-Countries (UMICs) (n = 51). CONCLUSIONS: While each country will have a different approach to achieving UHC, strengthening the health workforce will need to be a key priority if they are to be successful in achieving UHC.

7.
J Environ Manage ; 264: 110450, 2020 Jun 15.
Article in English | MEDLINE | ID: mdl-32217325

ABSTRACT

Owing to the growing volumes of ash and sewage sludge waste, there is a requirement for theoretical and practical research into the use of these wastes as a source of nutrients. However, there are relatively few studies on the transfer of macronutrients in soil-plant systems amended with ash-sewage sludge mixtures under field conditions. The aim of the study was to determine the effect of bituminous coal ash (AC), biomass ash (AB), and municipal sewage sludge (MSS) on the quantity and quality of a grass-legume mixture. During a 6 year field experiment on a sandy loam soil treated with the wastes, applied as mixtures or separately, the plant yield; N, P, K, Na, Mg, and Ca uptake by plants; macronutrient content and ratios in the plant biomass; and the recovery rate of macronutrients by plants were evaluated. The AB-MSS treatment increased the yield in comparison to that where the wastes were applied separately. The N, P, and Ca contents in the plant biomass and N and P uptake under ash-sludge treatments were in the range observed for the ash and sewage sludge. The AB-MSS co-application resulted in the highest K uptake. The AC-MSS treatment increased K and Mg uptake in relation to AC treatment. When AC or AB was added to the MSS, the Ca uptake increased relative to the MSS treatment. The plant biomass under the AB treatment was optimal for biofuel purposes in terms of the chemical composition. The co-application of AC or AB with MSS resulted in the optimum Ca:Mg ratio for fodder purposes. The recovery rate of the macroelements decreased in the following order: K, N, P, Mg, Na, and Ca. The results support the co-application of solid wastes such as ash and municipal sewage sludge to improve productivity, support the recycling of macronutrients, improve sustainability through the reduction of ash and sewage sludge disposal, and reduce reliance on mineral fertilizer.


Subject(s)
Sewage , Soil , Biomass , Coal Ash , Fertilizers , Nutrients
8.
J Environ Sci (China) ; 90: 20-28, 2020 Apr.
Article in English | MEDLINE | ID: mdl-32081316

ABSTRACT

In this study, we investigated the effect of sample pretreatments (ultrasonication and alkaline extraction) on total organic carbon (TOC) measurements for water samples containing suspended solids (SS) of four different origins (algae, soil, sewage sludge, and leaf litter) to more clearly assess the impact of particulate organic carbon (POC) in water. The effects each of ultrasonication (power, pulse, etc.) and alkaline extraction condition (concentration, time, etc.) on the TOC recovery and precision were investigated, and the results were compared with those of a new sample pretreatment method combining both methods. Alkaline treatment (0.01 mol/L NaOH) showed higher precision than ultrasonication (100/5 on/off pulse), and notably, the differences among the measured TOC values in samples of different origins were also further reduced in the alkaline treatment. This suggests that the ultrasonic pretreatment results can be mainly attributed to the increase in POC recovery through particle size reduction, whereas the alkaline treatment results are achieved through the enhancement of POC solubilization. It is also particularly noteworthy that a higher TOC recovery of 87.6% ± 7.4% with a higher precision of 8.4% could be obtained using the combined method, compared to each treatment (ultrasonic: TOC recovery 34.7%, relative standard deviation 63.1%; alkaline: 49.6% and 23.0%, respectively). Thus, simultaneous pretreatment with ultrasonication and alkaline extraction is expected to increase the oxidation rate of organic matter and the homogeneity of the samples, minimizing the loss of POC measurement values, and thereby improving the reliability of the TOC measurements of water samples containing SS.


Subject(s)
Sewage , Ultrasonics , Water Purification/methods , Carbon , Reproducibility of Results , Water
9.
J Environ Manage ; 261: 110158, 2020 May 01.
Article in English | MEDLINE | ID: mdl-32001432

ABSTRACT

The typical treatment scheme of a large municipal wastewater treatment plant (LWWTP) is almost always the result of design based on technical and economic criteria. Once a threshold in terms of population equivalent (PE) is reached, it is possible that additional sludge thermal treatment might be required. Aspects such as greenhouse gas (GHG) emissions and land use for the construction of the WWTP or the service landfill are considered marginal in current design practice; in a world that requires increasingly attention to the environment, these criteria cannot be ignored when defining the treatment scheme of a LWWTP. With the intent of providing a sustainable approach to design, this study aims to identify the best treatment scheme for a LWWTP with a 720,000 PE size. Methodologically, the study involves the development of an approach based on multi-criteria decision analysis (MCDA). Six alternative treatment schemes were considered; two simplified schemes, without primary sedimentation, with extended aeration activated sludge processes and aerobic sludge stabilization; four full schemes, with primary sedimentation and anaerobic sludge digestion. Some schemes differ for the organic loading rate applied; others for the use of sludge incineration. Subsequently, six evaluation criteria (ECs) such as GHG emissions, electricity consumption, running costs, WWTP planimetric area, surface for the service landfill, as well as WWTP as biorefinery have been considered. The weighting of the ECs involved the participation of the main stakeholders in such a decision-making process, following a bottom-up approach. The resolution of the MCDA problem allowed the identification of the full scheme based on primary sedimentation, biological activated sludge at low organic load (0.210 kgBOD5/kgVSS/d) and anaerobic sludge digestion as the best solution. The sensitivity analysis, able to indirectly take into account the multitude of decision makers involved, allowed corroborating the results. The obtained treatment scheme was different from that generally adopted in current design practice for LWWTPs.


Subject(s)
Waste Disposal, Fluid , Waste Water , Decision Support Techniques , Incineration , Sewage
10.
Water Res ; 173: 115570, 2020 Apr 15.
Article in English | MEDLINE | ID: mdl-32062221

ABSTRACT

Recent findings have demonstrated that activated sludge morphology significantly impacts oxygen transfer efficiency (OTE) in the activated sludge process. In this study, we developed a mechanistic understanding of this impact. Mixed liquor samples collected from a domestic wastewater treatment plant (WWTP) were blended with a bulking activated sludge from a bench scale reactor (BSR) cultured on synthetic wastewater to manipulate various morphological parameters such as the settled sludge volume (SV), the sludge volume index (SVI), and the specific filament length (SFL). The filaments that were present in the blended sludges consisted largely of Type 0041 and Type 021N, which are commonly found in WWTPs that treat domestic wastewater. Variations in sludge morphology, as quantified by settled sludge volume after 30 min (SV30), SVI, and SFL, systematically affected the mixed liquor apparent viscosity (µapp), which consequently impacted OTE. An increase in the SFL from 9.61 × 106 µm g-1 to 6.88 × 107 µm g-1 resulted in a 41.4% increase in apparent viscosity and a 24.6% decrease in volumetric mass transfer coefficient (KLa). A new parameter, named the ultimate settleability (SVULT), was developed by curve fitting the SV versus time data and found to relate with µapp through an expanded form of the Einstein Equation for the viscosity. Therefore, SVULT is a corollary for the particle volume fraction that incorporates effects of both the sludge morphology and mass concentration on µapp. Theoretical derivation revealed that an increase in SVULT resulted in an increase in µapp, which reduced oxygen transfer by increasing the air bubble size and reducing refreshment of the liquid at the gas-liquid interface. The KLa was found to be inversely proportional to µapp0.75 through fitting the experimental data with the theoretical model. Using a variance-based global sensitivity analysis, three operating parameters that have the most impact on oxygen transfer were identified: the power input per unit volume, the superficial gas flowrate, and the µapp.


Subject(s)
Oxygen , Sewage , Air , Bioreactors , Viscosity , Waste Disposal, Fluid , Waste Water
11.
J Environ Manage ; 255: 109945, 2020 Feb 01.
Article in English | MEDLINE | ID: mdl-32063313

ABSTRACT

In this study, the efficiencies of selected wastewater treatment plants (WWTPs) to remove selected perfluoroalkyl substances (PFASs) during wastewater treatment processes were evaluated. For this purpose, influent samples from Daspoort, Zeekoegat and Phola WWTPs, were initially screened for the presence of sixteen different PFASs of which only seven were detected. These include: perfluorobutanoic acid (PFBA), perfluoro-n-pentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonate (L-PFHxS), and perfluorooctane sulfonate (L-PFOS). To determine the concentrations of these PFASs, wastewater samples were subjected to solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. The results showed that L-PFOS was the dominant compound with the highest concentration of 508 ± 258 ng/L at Daspoort WWTP. Overall, the three WWTPs could not achieve the complete influent-to-effluent removal of the PFASs and the best removals were observed at Zeekoegat WWTP. The removal efficiency of the different unit processes varied from one plant to another and also from each type of PFASs. At Daspoort, the removal efficiency of the primary settling tanks was poor and the highest removal reached 39% for PFHxA. The activated sludge (AS) of this WWTP achieved the highest removal of 84% for the L-PFOS. At Zeekoegat, the AS achieved the highest removal of 94% for the L-PFOS. The anaerobic pond at Phola achieved a higher removal of 80% for the L-PFOS. However, no removal was observed downstream of the biological filter for the same compound. Poor removal efficiency was reported downstream of the wetland at Phola except for the PFOA (16%).


Subject(s)
Alkanesulfonic Acids , Fluorocarbons , Water Pollutants, Chemical , Environmental Monitoring , Sewage , Solid Phase Extraction , Waste Water
12.
Terminology | DeCS - Descriptors in Health Sciences | ID: 057351

ABSTRACT

Universal health coverage implies that all people have access, without discrimination, to nationally determined sets of the promotive, preventive, curative and rehabilitative basic health services needed and essential, safe, affordable, effective and quality medicines, while ensuring that the use of these services does not expose the users to financial hardship, with a special emphasis on the poor, vulnerable and marginalized segments of the population (From: Social Protection and universal health coverage. UN General Assembly, 67th Section, 2012. p.4. Available in: http://www.un.org/en/ga/search/view_doc.asp?symbol=A/RES/67/81). UHC is firmly based on the WHO constitution of 1948 declaring health a fundamental human right and on the Health for All agenda set by the Alma Ata declaration in 1978. UHC cuts across all of the health-related Sustainable Development Goals (SDGs) and brings hope of better health and protection for the world’s poorest. (From: What is Universal coverage? WHO, 2017. Available in: http://www.who.int/health_financing/universal_coverage_definition/en/)


La cobertura universal de salud implica que todas las personas tienen acceso, sin discriminación, a los conjuntos de servicios básicos de salud promocionales, preventivos, curativos y rehabilitadores necesarios y de medicamentos esenciales, seguros, asequibles, eficaces y de calidad, asegurando al mismo tiempo que el uso de estos servicios no expone a los usuarios a dificultades financieras, con un énfasis especial en los segmentos pobres, vulnerables y marginados de la población (Traducción libre del original: Social Protection and universal health coverage. UN General Assembly, 67th Section, 2012. p.4. Disponible en: http://www.un.org/en/ga/search/view_doc.asp?symbol=A/RES/67/81). La UHC está firmemente basada en la constitución de la OMS de 1948, declarando la salud como un derecho humano fundamental y en la agenda de Salud para Todos establecida por la Declaración de Alma Ata en 1978. El UHC incluye todos los Objetivos de Desarrollo Sostenible relacionados con la salud (SDGs) y trae la esperanza de una mejor salud y protección para los más pobres del mundo. (Traducción libre del original: What is Universal coverage? WHO, 2017. Disponible en: http://www.who.int/health_financing/universal_coverage_definition/en/)


A cobertura universal da saúde implica que todas as pessoas têm acesso, sem discriminação, a conjuntos de serviços de saúde promocionais, preventivos, curativos e de reabilitação determinados a nível nacional necessários e medicamentos essenciais, seguros, acessíveis, eficazes e de qualidade, assegurando ao mesmo tempo que o uso desses serviços não expõe os usuários a dificuldades financeiras, com ênfase especial nos segmentos pobres, vulneráveis e marginalizados da população (Tradução livre do original: Social Protection and universal health coverage. UN General Assembly, 67th Section, 2012. p.4. Disponível em: http://www.un.org/en/ga/search/view_doc.asp?symbol=A/RES/67/81). A UHC baseia-se firmemente na constituição da OMS de 1948 que declara a saúde como um direito humano fundamental e na agenda de Saúde para Todos definida pela declaração de Alma Ata em 1978. A UHC perpassa todos os Objetivos de Desenvolvimento Sustentável (ODSs) relacionados à saúde e traz esperança de melhor saúde e proteção para os mais pobres do mundo. (Tradução livre do original: WHO, Universal health coverage and health financing, 2017 Disponível em: http://www.who.int/health_financing/universal_coverage_definition/en/).

13.
J Environ Manage ; 258: 110013, 2020 Mar 15.
Article in English | MEDLINE | ID: mdl-31929055

ABSTRACT

The effect of competition between isolated petroleum-degrading bacteria (PDB) and indigenous compost microorganisms (ICM) on the efficiency of composting process in bioremediation of petroleum waste sludge (PWS) was investigated. After isolating two native PDB (Acinetobacter radioresistens strain KA5 and Enterobacter hormaechei strain KA6) from PWS, their ability for growth and crude oil degradation was examined in the mineral-based culture (MBC). Then, the PDB isolate were inoculated into the composting experiments and operated for 12 weeks. The results showed that the PDB degraded 21.65-68.73% of crude oil (1-5%) in the MBC after 7 days. The PDB removed 84.30% of total petroleum hydrocarbon (TPHs) in the composting bioreactor containing the initial TPH level of 20 g kg-1. Removal of petroleum hydrocarbons (PHCs) in the composting experiments proceeded according to the first-order kinetics. The computed values of degradation rate constants and half-lives showed a better performance of the PDB than ICM for TPHs removal. This finding suggests that simultaneous application of the PDB and ICM in the composting reactors resulted in a decline in the effectiveness of the PDB which is due to competition between them. The study also verified that the capability of PDB in degrading PHCs can be successfully scaled-up from MBC to composting process.


Subject(s)
Composting , Petroleum , Soil Pollutants , Biodegradation, Environmental , Hydrocarbons , Minerals , Sewage , Soil Microbiology
14.
Bioresour Technol ; 300: 122622, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31891856

ABSTRACT

Simultaneous enzymatic saccharification and comminution (SESC) was used for large-scale anaerobic digestion of wood lignocellulose to generate methane and unmodified lignin. During SESC, 10% aqueous mixture of powdered debarked wood from various species was subjected to bead milling with hydrolytic enzymes to generate particles below 1 µm. This slurry was directly used as a cosubstrate for anaerobic digestion in a 500 L stirred-tank reactor. Temperature and hydraulic retention time (HRT) were maintained at 50 °C and 30 days, respectively. At stable operation periods, an average yield of 224 L of methane per kg of cedar was attained. Comparable yields were achieved with red pine, elm, oak, and cedar bark. High-throughput microbial analysis established the presence of a relevant community to support the elevated level of methane production. The stability of the unmodified lignin in anaerobic digestion was also confirmed, allowing for its recovery as an important by-product.


Subject(s)
Lignin , Sewage , Anaerobiosis , Bioreactors , Methane , Wood
15.
Bioresour Technol ; 297: 122506, 2020 Feb.
Article in English | MEDLINE | ID: mdl-31812600

ABSTRACT

Sludge reduction via microbial metabolism does not require extra energy and resource inputs and thus merits attention as an alternative approach for sustainable wastewater treatment. This review presents a summary and analysis of the existing literatures on sludge reduction based on microbial metabolism, as well as interprets these sludge reduction mechanisms using bacterial thermodynamics and stoichiometry. Future efforts should be directed toward using advanced analytical techniques to further reveal sludge reduction mechanisms. The feasibility of coupling sludge reduction and nutrient removal by microorganism metabolism needs to be further evaluated to minimize the effect of sludge reduction on nutrient removal. A comprehensive life cycle assessment of sludge reduction strategies is recommended to effectively confirm their sustainability. Full-scale research is needed to verify the results obtained from bench- and pilot-scale experiments. This review presents the future opportunities and challenges for sludge reduction based on microbial metabolism in the excess sludge disposal.


Subject(s)
Sewage , Waste Water , Bacteria , Waste Disposal, Fluid
16.
Water Res ; 170: 115298, 2020 Mar 01.
Article in English | MEDLINE | ID: mdl-31751893

ABSTRACT

Handling excess sludge produced by wastewater treatment is a common problem worldwide. Due to limited space available in landfills, as well as difficulties involved in using excess sludge in agriculture, there is a need for alternative disposal methods. Although anaerobic digestion (AD) is widely used in processing sludge, only partial energy recovery from methane and sludge volume reduction can be achieved, resulting in a substantial amount of sludge remaining, which needs to be disposed of. Direct incineration after sludge drying is one possible option, a practice that is already in place in some cities in China. A comparison between direct incineration and conventional AD (with or without pretreatment by thermal hydrolysis) has to be made with respect to the energy balance and investment & operational (I & O) costs. This comparison reveals direct incineration to have the lowest energy deficit and I & O costs. Therefore, it is expected that direct incineration without AD will become the preferred sustainable approach to handling sludge.


Subject(s)
Incineration , Sewage , Anaerobiosis , China , Cities , Methane , Waste Disposal, Fluid
17.
Waste Manag ; 102: 97-105, 2020 Feb 01.
Article in English | MEDLINE | ID: mdl-31669679

ABSTRACT

Generally, the bio-treatment effluent of municipal solid waste incineration (MSWI) leachate was difficult to meet the local leachate discharge standards for chemical oxygen demand (COD) (100 mg/L), ammonia nitrogen (NH4+-N) (25 mg/L), and total nitrogen (TN) (40 mg/L), and advanced treatment (such as coagulation, membrane filtration, advanced oxidation) is required. However, the cost of advanced treatments is proportional to the concentration of the pollutant. Therefore, improved bio-treatment efficiency is the key to reduce the treatment cost of MSWI leachate. In this study, the up-flow anaerobic sludge blanket (UASB) -modified Bardenpho process was used for the treatment of MSWI leachate. The results showed that it was feasible to dilute the leachate by recirculation of the settling tank effluent, which has great significance in the bio-treatment efficiency. The treatment process achieved removal efficiencies of COD and NH4+-N of 97.5-99.5% and 99.3-99.7%, respectively. Adjustments to the operational conditions of the primary anoxic tank, such as adding an organic carbon source and increasing the hydraulic retention time and the nitrification reflux ratio resulted in a TN removal efficiency of 97.7-98.7%. Controlling the generation of dissolved organic nitrogen (DON) and increasing its removal efficiency significantly improved the TN removal efficiency. The concentrations of NH4+-N and TN in the settling tank effluent complied with the local leachate discharge standard, which minimized the cost of advanced treatment. The results provide new ideas for enhancing the bio-treatment efficiency of leachate and theoretical and technical support for reducing the cost of treatment.


Subject(s)
Solid Waste , Water Pollutants, Chemical , Bioreactors , Incineration , Nitrogen , Sewage , Waste Disposal, Fluid
18.
Water Res ; 169: 115193, 2020 Feb 01.
Article in English | MEDLINE | ID: mdl-31670083

ABSTRACT

The positive roles of N-acyl homoserine lactone (AHL)-mediated quorum sensing (QS) in aerobic granular sludge (AGS) have been widely acknowledged. However, it is not feasible to manipulate granulation via direct addition of AHL chemicals or AHL-producing strains. Here, several strains with high AHL-producing capacity were successfully isolated from AGS. These QS strains were cultivated, mixed as a consortium, and then divided into two groups: AHLs supernatant and bacterial cells encapsulated in sodium alginate (CEBs). The potential of QS regulation, via doses of AHLs supernatant and CEBs, in accelerating granulation was evaluated. Results clearly indicated that short-term (days 21-70) addition of AHLs supernatant led to a rapid specific growth rate (0.08 d-1), compact structure without filamentous bacteria overgrowth, excellent settlement performance (SVI10 37.2 mL/g), and a high integrity coefficient (4.4%) of the granules. Sustainable release of AHLs (mainly C6- and C8-HSL) was induced by exogenous AHLs, possibly attributed to the enrichment of the genera Aeromonas and Pseudomonas. Further, tryptophan and aromatic protein substances were produced to maintain structural stability, suggesting that short-term QS regulation had long-term positive effects on the characteristics of AGS. By comparison, the addition of CEBs posed negligible or negative impact on the granulation, as evidenced by the rupture of smaller aggregates and poor characteristics of AGS. Overall, augmentation of the signaling content via addition of AHLs supernatant from QS strains is an economical and feasible regulation strategy to accelerate granulation and sustain long-term structural stability.


Subject(s)
4-Butyrolactone , Quorum Sensing , 4-Butyrolactone/analogs & derivatives , Acyl-Butyrolactones , Bacteria , Sewage
19.
Bioresour Technol ; 296: 122280, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31693972

ABSTRACT

Effects of additional alkalinity on the performance of aerobic granular sludge (AGS) in sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) were evaluated. Results showed that COD and ammonia-N (NH4+-N) were slightly stimulated and remained high and stable with the increase of alkalinity up to 750 mg/L, while denitrification was boosted and total inorganic nitrogen (TIN) removal efficiency increased from 60.46% to 98.62% with an additional alkalinity of 750 mg/L. However, total phosphorus (TP) removal stayed unaffected and efficient. Illumina MiSeq sequencing revealed that microbial diversity and richness shifted mostly with 500 mg/L exterior alkalinity addition. Additional alkalinity altered the bacterial compositions within aerobic granules at various levels and the enrichment of Thiothrix and Acinetobacter was accounted for the promotion of COD and TIN removal.


Subject(s)
Bioreactors , Sewage , Denitrification , Nitrification , Nitrogen , Phosphorus , Waste Disposal, Fluid
20.
Ecotoxicol Environ Saf ; 188: 109818, 2020 Jan 30.
Article in English | MEDLINE | ID: mdl-31689659

ABSTRACT

The occurrence, removal efficiency, mass loading and environmental emission of four categories (benzotriazoles; parabens; antimicrobials; benzophenones) of personal care products were simultaneously determined along the whole process line through an integrated approach (involving both dissolved and adsorbed phase) at a typical wastewater treatment plant in Hunan Province, Southern China. The results showed the prevalence of 13 and 11 target compounds in wastewater and suspended particulate matter, respectively. Twelve substances were detected in the sludge with the mean concentrations ranging from 0.12 to 591.23 ng/g dry weight. Benzotriazoles were the dominant compounds existing in water and antimicrobials were readily being absorbed onto suspended particulate matter and sludge. The overall removal efficiencies of compounds in the total treatment were -84.06%-98.53%. Mass balance results revealed that 85.17%-98.73% of the parabens and benzophenones were removed by degradation, while antimicrobials were removed by being adsorbed onto sludge. However, benzotriazoles could not be efficiently removed and the mass loss was lower than 61.03%. Although ultraviolet radiation played a limited role in removing most target compounds, it still had an impact on removing antimicrobials, 5,6-dimethyl-1H-benzotriazole and 2-hydroxy-4-methoxybenzophenone. The total mass loading and emission of personal care products were 506.35 mg/d/1000 people and 357.56 mg/d/1000 people, respectively. This work would help understand the removal approaches and real pollution of personal care products in the water environment.


Subject(s)
Cosmetics/analysis , Sewage/chemistry , Ultraviolet Rays , Waste Water/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Adsorption , China , Cosmetics/chemistry , Water Pollutants, Chemical/chemistry
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