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1.
Environ Monit Assess ; 192(10): 625, 2020 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-32897491

RESUMO

Donnybrook Waste Stabilization Ponds (WSP) are overloaded and water hyacinth plants have infested the ponds. The study assessed the feasibility of integrating the problematic water hyacinth plants into the current treatment process. Grab samples of influent and effluent for each pond were collected between 28 March and 23 April 2019 and the analysis was done following standard APHA methods. Parameters considered include pH, turbidity, TDS, TSS, TN, TP, BOD, and COD. The raw sewage mean pH, turbidity, TDS, TSS, TN, TP, BOD, and COD were 8.08, 580 NTU, 1639 mg/L, 1294 mg/L, 78 mg/L, 8.16 mg/L, 287 mg/L, and 887 mg/L. The mean pH, turbidity, TDS, TSS, TN, TP, BOD, and COD in the effluent from the existing maturation pond, control pilot pond, and water hyacinth pilot pond were 7.7, 7.7, and 7.3; 75, 67, and 47 NTU; 861, 758, and 668 mg/L; 276, 172, and 82 mg/L; 27, 28, and 17 mg/L; 4, 5.28, and 4 mg/L; 114, 52, and 30 mg/L; and 243, 122, and 81 mg/L. It was concluded that the water hyacinth may be integrated into the WSP system to enhance contaminant removal. The water hyacinth in the ponds should be harvested periodically to avoid secondary organic and nutrient loading from dead plants.


Assuntos
Eichhornia , Purificação da Água , Monitoramento Ambiental , Tanques , Esgotos , Eliminação de Resíduos Líquidos , Águas Residuárias , Zimbábue
2.
Water Sci Technol ; 82(1): 27-38, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910790

RESUMO

The present study describes a pilot-scale experimental validation of a forced-convection greenhouse solar dryer, combined with a biofilter, for controlled atmospheric emissions. This set-up was applied to the dewatering of sewage sludge from a biological plant that treated process wastewater in a commercial Mediterranean winery. Experiments were performed after the harvest, from September onwards, during the peak generation of sludge. The average drying rate during the first 10 days of operation ranged from 1.17 to 2.24 kg m-2 d-1, depending on the measurement method, during which the water content of the sludge was reduced from 90% down to 67%. Biofiltration was quite inefficient against greenhouse gases (methane and dinitrous oxide), and direct emissions during the drying process were on average 57 g CO2-eq m-2 d-1. Ammonia and volatile organic compounds were removed with average efficiencies of 71% and 35%, but ammonia losses through volatilization represented less than 2% of the initial nitrogen content. The sludge was dried further during November, to the lowest possible water content of 14%. Both the intermediate and final sludge dried materials were characterized for their agronomical value as organic fertilizers.


Assuntos
Dessecação , Esgotos , Fazendas , Nutrientes , Águas Residuárias
3.
Water Sci Technol ; 82(1): 120-130, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910797

RESUMO

In order to investigate the effect of temperatures and operating modes on extracellular polymeric substances (EPS) contents, three sequencing batch reactors (SBRs) were operated at temperatures of 15, 25, and 35 °C (R15 °C, R25 °C, and R35 °C, respectively), with two SBRs operated under alternating anoxic/oxic conditions (RA/O and RO/A, respectively). Results showed that higher contents of tightly bound EPS (TB-EPS) and total EPS appeared in R15 °C, while loosely bound EPS (LB-EPS) dominated in R35 °C. In all three kinds of EPS (LB-EPS, TB-EPS and total EPS) assessed, protein was the main component in R15 °C and R25 °C, while polysaccharides dominated in R35 °C. Moreover, compared with RO/A, RA/O was favorable for the production of the three kinds of EPS. Furthermore, three kinds of EPS and their components were augmented during the nitrification process, while they declined during the denitrification process under all conditions except for R35 °C.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Esgotos , Reatores Biológicos , Nitrificação , Temperatura
4.
Sci Total Environ ; 741: 140480, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886969

RESUMO

The co-treatment of two synthetic faecal sludges (FS-1 and FS-2) with municipal synthetic wastewater (WW) was evaluated in an aerobic granular sludge (AGS) reactor. After characterisation, FS-1 showed the following concentrations, representative for medium-strength FS: 12,180 mg TSS L-1, 24,300 mg total COD L-1, 93.8 mg PO3-P L-1, and 325 mg NH4-N L-1. The NO3-N concentration was relatively high (300 mg L-1). For FS-2, the main difference with FS-1 was a lower nitrate concentration (18 mg L-1). The recipes were added consecutively, together with the WW, to an AGS reactor. In the case of FS-1, the system was fed with 7.2 kg total COD m-3d-1 and 0.5 kg Nitrogen m-3d-1. Undesired denitrification occurred during feeding and settling resulting in floating sludge and wash-out. In the case of FS-2, the system was fed with 8.0 kg total COD m-3d-1 and 0.3 kg Nitrogen m-3d-1. The lower NO3-N concentration in FS-2 resulted in less floating sludge, a more stabilised granular bed and better effluent concentrations. To enhance the hydrolysis of the slowly biodegradable particulates from the synthetic FS, an anaerobic stand-by period was added and the aeration period was increased. Overall, when compared to a control AGS reactor, a lower COD consumption (from 87 to 35 mg g-1 VSS h-1), P-uptake rates (from 6.0 to 2.0 mg P g VSS-1 h-1) and NH4-N removal (from 2.5 to 1.4 mg NH4-N g VSS-1 h-1) were registered after introducing the synthetic FS. Approximately 40% of the granular bed became flocculent at the end of the study, and a reduction of the granular size accompanied by higher solids accumulation in the reactor was observed. A considerable protozoa Vorticella spp. bloom attached to the granules and the accumulated particles occurred; potentially contributing to the removal of the suspended solids which were part of the FS recipe.


Assuntos
Esgotos , Águas Residuárias , Reatores Biológicos , Nitrogênio , Eliminação de Resíduos Líquidos
5.
Sci Total Environ ; 741: 140513, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32887002

RESUMO

The dynamics of microbial necromass of municipal solid waste over long-term landfill remain unknown. This study presents the first investigation on the dynamics of bacterial and fungal necromass of municipal sludge in non-aeration versus alternating aeration landfill bioreactors by using amino sugar biomarkers. Results showed that under non-aeration treatment, the decomposition rate of muramic acid derived from bacteria is higher than that of fungal-derived glucosamine. The relative change in glucosamine and muramic acid in the early period of landfills under the alternating aeration treatment is consistent with that under non-aeration treatment. However, with the increase in alternating aeration cycles, bacterial necromass muramic acid exerts a lower decomposition rate than fungal necromass glucosamine. Throughout the entire landfill period, galactosamine is the amino sugar with the slowest decomposition rate under non-aeration mode but the amino sugar with the fastest decomposition rate under alternating aeration mode. The present work fills the knowledge gap of microbial necromass dynamics of municipal solid waste in landfills.


Assuntos
Eliminação de Resíduos , Esgotos , Amino Açúcares , Bactérias , Biomarcadores , Reatores Biológicos , Instalações de Eliminação de Resíduos
6.
Sci Total Environ ; 741: 140071, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32887015

RESUMO

The application of quantitative polymerase chain reaction (qPCR) based microbial source tracking (MST) marker genes are increasingly being used to identify contaminating sources and inform management decisions. In this study, we assessed interlaboratory agreement on duplicate environmental water samples collected from estuarine and freshwater locations, by comparing results of qPCR based testing for Bacteroides HF183, crAssphage CPQ_056, and pepper mild mottle virus (PMMoV). The overall agreements (co-detection and non-co-detection) between CSIRO Land and Water (CLW) laboratory and Sydney Water (SW) laboratory for the HF183, crAssphage CPQ_056 and PMMoV marker genes for duplicate water samples were 74, 75 and 74%, respectively. Cohene's kappa (k) revealed fair to moderate agreements and acceptable relative percent difference (RPD) values of <15% for duplicate samples. The pooled mean abundances of HF183, CPQ_056, and PMMoV in measurable samples at the CLW laboratory were 5.19 ± 0.93, 5.12 ± 0.82, and 4.42 ± 0.65 log10 copies/L, respectively. However, the pooled mean abundances were significantly lower at the SW laboratory, HF183 (4.58 ± 0.84 log10 copies/L), crAssphage CPQ_056 (4.20 ± 0.63 log10 copies/L), and PMMoV (3.89 ± 0.41 log10 copies/L). At individual sample level, most of the paired samples had <1 log10 difference. Significant positive Spearman rank correlations were obtained between two laboratories for the HF183 (Rs = 0.65; p < 0.05), CPQ_056 (Rs = 0.79; p < 0.05), and PMMoV (Rs = 0.54; p < 0.05) marker genes. Several factors such as standards, qPCR platforms, PCR inhibitors, nucleic acid extraction efficiency and low levels of targets in some samples may have contributed to the observed discrepancies. Results presented in this study highlight the importance of standardized protocol, laboratory equipment (such as digital PCR), sample processing strategies and appropriate quality controls that may need implementation to further improve accuracy and precision of results between laboratories.


Assuntos
Rios , Esgotos , Monitoramento Ambiental , Fezes , Água Doce , Microbiologia da Água , Poluição da Água/análise
7.
J Environ Manage ; 263: 110368, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32883474

RESUMO

Nowadays, alternative options to conventional wastewater treatment should be studied due to rising concerns emerged by the presence of pharmaceuticals compounds (PhCs) in the aquatic environment. In this work, a combined system including biological treatment by activated sludge plus adsorption with activated carbon is proposed to remove three selected drugs (acetaminophen (ACT), caffeine (CAF) and ibuprofen (IBU)) in a concentration of 2 mg L-1 of each one. For it three sequencing batch reactors (SBR) were operated. SBR-B treated a synthetic wastewater (SWW) without target drugs and SBR-PhC and SBR-PhC + AC operated with SWW doped with the three drugs, adding into SBR-PhC + AC 1.5 g L-1 of a mesoporous granular activated carbon. Results showed that the hybrid system SBR-activated carbon produced an effluent free of PhCs, which in addition had higher quality than that achieved in a conventional activated sludge treatment in terms of lower COD, turbidity and SMP concentrations. On the other hand, five possible routes of removal for target drugs during the biological treatment were studied. Hydrolysis, oxidation and volatilization pathways were negligible after 6 h of reaction time. Adsorption route only was significant for ACT, which was adsorbed completely after 5 h of reaction, while only 1.9% of CAF and 5.6% of IBU were adsorbed. IBU was the least biodegradable compound.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Adsorção , Reatores Biológicos , Esgotos
8.
J Environ Manage ; 263: 110395, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32883477

RESUMO

One of the main drawbacks of upflow anaerobic sludge blanket (UASB) reactors that treat low-strength sewage at room temperature is related to the low quality of their effluents in terms of dissolved methane, organic matter, and nitrogen content. The present study aims to evaluate the feasibility of using an integrated fixed-film activated sludge (IFAS) system as an alternative post-treatment technology to mitigate the environmental impact of such effluents. For this purpose, a pilot plant composed of a UASB (120 L) followed by an IFAS (66 L) system was operated for 407 days. Special attention was paid to the suspended biomass retention capacity and the dissolved methane and nitrogen removal potential of the IFAS post-treatment system. Furthermore, the role of carriers on denitrification and nitrification processes and the microbial communities present in the biofilm were also analyzed. Average total chemical oxygen demand (CODT) and ammonium removal efficiencies of 92 ± 3% and around 57 ± 16% were attained throughout the entire operation, respectively. During a first period in which biomass was maintained in both biofilms and suspension, and nitrite was the main electron acceptor, maximum nitrogen removal and methane removal efficiencies of 32.5 mg TN L-1 and 93% were observed in the IFAS system, respectively. However, throughout the second period, in which suspended biomass was completely washed out from the IFAS system, and nitrate became the main electron acceptor, these values decreased to 18 ± 4 mg TN Lfeed-1 and 77 ± 12%, respectively. Surprisingly, throughout the entire operation, it was observed that around 50 and 41% of the total nitrogen and methane removals observed in the IFAS system, respectively, were carried out in the aerobic compartment. Aerobic methane oxidizers and anammox were detected with significant relative abundances in the biofilm carriers used in the anoxic and aerobic compartments using 16S rRNA gene amplicon sequencing analysis. Therefore, the use of an IFAS system could be suited to diminish greenhouse gas emissions and nutrients concentration for those sewage treatment plants that used UASB systems, especially in countries with temperate and warm climates.


Assuntos
Nitrogênio , Esgotos , Anaerobiose , Reatores Biológicos , Metano , RNA Ribossômico 16S , Eliminação de Resíduos Líquidos
9.
J Environ Manage ; 263: 110420, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32883483

RESUMO

This study proposed the recycling of sewage sludge (SS) and red gypsum (RG) as potential temporary landfill cover materials. Mixtures with different SS and RG compositions were prepared and tested in determining the most suitable design mix based on the resulting physical, mechanical, and geotechnical properties, namely the hydraulic conductivity, compressive strength, and plasticity. A maximum compressive strength of 524 kPa was achieved for the optimum SS:RG composition of 1:1, corresponding to Ca:Si composition of 2.5:1, which was appropriate to form the calcium silicate hydrate (CSH) gel. The SS and RG compositions did not affect the hydraulic conductivity, which was in the order 10-5 cm/s for all mixtures. Mixtures with RG greater than SS in composition exhibited plastic behaviour due to the Fe content in the RG, which helped minimize the risk of cracking. The optimum mixture had compressive strength greater than the specified minimum of 345 kPa, medium hydraulic conductivity, and moderate plasticity, thus appropriate for application as an alternative material for the temporary landfill cover in the tropics.


Assuntos
Sulfato de Cálcio , Esgotos , Instalações de Eliminação de Resíduos
10.
Sci Total Environ ; 738: 140277, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806351

RESUMO

Although bacterial degradation of polynuclear aromatic hydrocarbons (PAH) have been studied using various pure cultures, only a few studies have explored the degradation kinetics and uptake mechanism of nitrogen heterocyclic PAHs (PANH) with three or more rings. This work explored growth kinetics of a PAH degrading bacterial strain, Pseudomonas aeruginosa RS1 on carbazole (CBZ) and concomitant degradation kinetics of CBZ over the concentration range 25 to 500 mg/L. For CBZ acclimatized strain, the specific growth rate (µ) and specific CBZ uptake rate (q) varied from 0.96 ± 0.05 to 2 ± 0.15 day-1 and from 0.002 ± 0.001 to 0.02 ± 0.01 mg CBZ mg VSS-1 day-1, respectively. The Moser and Monod model provided best fits to the µ vs CBZ concentration and q vs CBZ concentration profiles, respectively. Biosurfactant activity did not play a role in CBZ uptake. However, elevation in cell surface hydrophobicity as revealed through the water contact angle values on bacterial cell mat indicated the possible role of direct interfacial uptake in facilitating CBZ uptake over and above uptake after dissolution. Elevated catechol 1,2-dioxygenase enzyme activity was observed during CBZ degradation. Interestingly, the specific activity of this enzyme was higher in the culture supernatant than in the cell extract. However, during CBZ degradation, accumulation of some toxic metabolites in the aqueous phase was revealed through increase in TOC of the aqueous phase and Kirby-Bauer disc diffusion study performed using a E. coli strain. Both aqueous phase TOC and toxicity decreased beyond the log growth phase indicating further utilization of the degradation intermediates.


Assuntos
Pseudomonas aeruginosa , Esgotos , Biodegradação Ambiental , Carbazóis , Escherichia coli , Cinética
11.
Sci Total Environ ; 738: 140320, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806367

RESUMO

In recent years, many biological and physicochemical treatment technologies have been investigated for the removal of the emerging contaminants (ECs) from the wastewater matrix. However, due to the deficiency of these treatments to completely degrade the ECs in wastewater, hybrid systems were explored using the distinguishing removal potential of the different treatment processes. This review gives an insight on such hybrid systems combining several physical, chemical and biological treatments for the fast and eco-efficient removal of ECs from wastewater. Most of the hybrid systems have applied biological treatments first and then physical or chemical treatments. The hybrid system of membrane bioreactor (MBR) followed by membrane filtrations (RO/NF) effectively removed a suite of ECs such as pharmaceuticals, beta blockers, pesticides and EDCs. Some of the hybrid systems of constructed wetlands and waste stabilization ponds showed promising potential for the biosorptive removal of pharmaceuticals and some beta blockers. The hybrid systems combining activated sludge process and physical processes such as ultrafiltration (UF), reverse osmosis (RO) and gamma radiations are considered as the cost effective technologies and had better removal of trace organic pollutants. The hybrid system of MBR coupled with UV oxidation, activated carbon and ultrasound, and ozonation followed by ultrasounds, completely degraded some ECs and many pharmaceuticals. The review also synthesizes the trend followed by the hybrid system processes for the removal of various categories of ECs. The future research directions for the ECs removal utilizing hybrid nanocomposites and green sustainable technology have been suggested.


Assuntos
Águas Residuárias , Poluentes Químicos da Água/análise , Reatores Biológicos , Esgotos , Eliminação de Resíduos Líquidos
12.
Environ Pollut ; 265(Pt A): 115095, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806410

RESUMO

Sludge is an inevitable by-product of municipal wastewater treatment processes, and its high moisture content poses a major challenge for its subsequent treatment and disposal. Previous studies have explored the effects of applying modified corn-core powder (MCCP) on dewatering sludge. Here, we characterized the effects of applying both MCCP and sludge-based biochar (SBB) on dewatering sludge. Analysis of the anti-shear ability of SBB revealed that SBB was a skeleton builder with high compressive strength, demonstrating that SBB could maintain the permeability of sludge under high-pressure filtration processes and facilitate the flow of bound water. Dissipative particle dynamics (DPD) was used to simulated the sludge flocculating process and verify the feasibility of the experiment. As the simulation progressed, the reaction in the sludge network reached equilibrium and the simulated structure of the sludge became loose. The dewatering performance and physicochemical properties of the treated sludge were studied to further characterize the effect of this combined technology. Compared with MCCP-sludge, MCCP&SBB-sludge, which was treated by 20% DS (mass of dry solids in sludge) of SBB and 20% DS of MCCP, achieved superior dewaterability. This combined method reduced the specific resistance of filtration by 76% and enlarged the net sludge solids yield by 138%. Further study of the properties of MCCP&SBB-sludge revealed a loose structure that resembled the structure recovered by the simulation, suggesting that the DPD simulation method simulated the sludge flocculating process successfully. Therefore, the combined application of MCCP and SBB was superior for sludge dewatering because of the synergistic effects of MCCP and SBB.


Assuntos
Esgotos , Zea mays , Carvão Vegetal , Eliminação de Resíduos Líquidos
13.
Water Sci Technol ; 81(12): 2585-2598, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32857745

RESUMO

Bioleaching, a technologically and economically feasible technology, is considered as the high efficiency method to improve dewaterability in sewage sludge. The objective of this study was to investigate the effect of different sludge concentrations on bioleaching dewaterability and understand the mechanism of the effect of bioleaching on sludge dewaterability. Variation in pH, oxidation-reduction potential (ORP), capillary suction time (CST), specific resistance to filtration (SRF) and different fractions of extracellular polymeric substances (EPS) including slime EPS (S-EPS), loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS) were determined. Different sludge concentrations (5, 10, 15, 20 and 30 g·L-1) were selected to investigate during bioleaching. Results indicated that sludge buffering capacity significantly inhibited bioleaching efficiency as sludge concentrations increased. Optimum enhancements in sludge dewaterability were observed during the 10 g·L-1 sludge concentration treatment, and reached a maximum when the pH was 2.11. The variation of different fractions of EPS revealed that the ratio of S-EPS/TB-EPS significantly affected sludge dewaterability. Principal component analysis and Pearson's correlation analysis both provided evidence that the higher TB-EPS followed by a very large reduction was positively correlated with sludge dewaterability. However, the increase of protein and DNA in S-EPS content was negatively correlated with sludge dewaterability.


Assuntos
Esgotos , Água , Matriz Extracelular de Substâncias Poliméricas , Filtração , Proteínas
14.
Water Res ; 182: 115955, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777640

RESUMO

The function of the microbiomes in wastewater treatment systems and anaerobic digesters is dictated by the physiological activity of their members and complex interactions between them. Since functional traits are often conserved at low taxonomic ranks (genus, species, strain), high resolution taxonomic classification is crucial to understand the role of microbes in any ecosystem. Here we present MiDAS 3, a comprehensive 16S rRNA gene reference database based on full-length 16S rRNA gene amplicon sequence variants (FL-ASVs) derived from activated sludge and anaerobic digester systems in Denmark. The new database proposes unique provisional names for all unclassified microorganisms down to species level, providing a new and much-needed tool for microbiome research. The MiDAS 3 database was used to analyze the microbiome in 20 Danish wastewater treatment plants with nutrient removal, sampled over 13 years. The 50 most abundant species belonged to 42 genera, including 14 genera with provisional 'midas' name. Of those, 20 have no known function in the system, which highlights the need for more efforts towards elucidating the role of important members of wastewater treatment ecosystems. The new MiDAS 3 database also forms the backbone of the MiDAS Field Guide - an online resource linking the identity of microorganisms in wastewater treatment systems to available data related to their functional importance. The new field guide contains a complete list of genera (>1800) and species (>4200) found in activated sludge and anaerobic digesters in Denmark, but is also relevant to wastewater systems across the world. The identity of the microbes is linked to functional information, where available, and the website provides the possibility to BLAST new sequences against the MiDAS 3 database. The MiDAS Field Guide is a collaborative platform acting as an online knowledge repository, facilitating understanding of wastewater treatment ecosystem function.


Assuntos
Microbiota , Esgotos , Anaerobiose , Filogenia , RNA Ribossômico 16S , Águas Residuárias
15.
Waste Manag ; 116: 22-30, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32781408

RESUMO

In Europe, approximately 40% of sludge yearly produced in wastewater treatment plants (WWTPs) is applied in agricultural lands as organic amendment, especially in arid regions. Sludge tends to concentrate wastewater pollutants. Many of them are not removed by sludge stabilization treatments and, as a result, they could originate adverse effects on soils, vegetation, animals, and humans. Although sludge stabilization treatments play an important role in removal contaminants from sludge and, therefore, in preventing contaminant discharges onto soils, there is scarce information about the occurrence of these compounds in these treatments. This fact is especially acute for emerging pollutants and, particularly, their metabolites. In this work, seven pharmaceuticals and personal care products, and their main metabolites, have been monitored in five different stabilization treatments: anaerobic and aerobic digestion, dehydration, composting, and lagooning. Sixteen compounds were measured in the analysed samples. Their distribution was similar in primary sludge, in spite of the different geographic locations of the WWTPs, The distribution was in accordance with the metabolic ratios of most of the studied compounds. Different behaviour was observed depending on the compound, for example, CBZ, 3-OH-CBZ, DIC, and 4-OH-DIC were highly persistent in all studied stabilization technologies whereas CAF, PX showed high degradability. Most of the studied compounds were measured in the final product of the sludge stabilization processes evaluated. This fact shows the necessity to improve the knowledge about the presence of these compounds in sludge intended to be applied onto soil and about the potential ecotoxicological risks of these compounds.


Assuntos
Cosméticos , Poluentes Químicos da Água/análise , Animais , Europa (Continente) , Humanos , Esgotos , Eliminação de Resíduos Líquidos , Águas Residuárias
16.
Waste Manag ; 116: 31-39, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32784119

RESUMO

This paper presents an inventory of sewage sludge ashes (SSA) generated in the mono-incineration plants for municipal sewage sludge in Poland. This research focused on the detailed study of mass flows, chemical composition, and phosphorus recovery potential. There are currently 11 sludge mono-incineration plants operated with a total capacity of 160,300 Mg dry weight (d.w.) of sludge annually. Recently, a significant increase in the amount of SSA generated in these plants has been observed, reaching 26,756 Mg in 2018. Chemical composition of SSA showed significant amounts of the main nutrients: calcium (~14%), phosphorus (~13%), magnesium (~3%), and potassium (~1%). Additional main elements were iron (~14.5%), silicon (~13%), and aluminium (~6%). The main trace elements in the SSA were zinc (~3750 mg/kg) and copper (~899 mg/kg). Pollutants, according to fertilizer regulations of different countries, present in Polish SSA were chromium (~703 mg/kg), nickel (~260 mg/kg), lead (~94 mg/kg), and cadmium (~9 mg/kg). The radionuclides, uranium, and thorium often present in higher amounts in commercial phosphate rock-based fertilizers, were only detected in SSA at low levels of 4-9 mg/kg and 2-3 mg/kg, respectively. Theoretical phosphorus recovery potential from the SSA (from plants in Cracow, Lodz, Gdansk, Gdynia, Szczecin, and Kielce) was estimated at 1613.8 Mg, of which 33.9% is bioavailable. Currently, in Poland, the recommended approach is the production of fertilizers as a result of the extraction of phosphorus from the SSA with its use in the production of secondary mineral fertilizers. Further research in this area is required considering Polish conditions and legislation.


Assuntos
Fósforo/análise , Esgotos , Fertilizantes , Incineração , Polônia
17.
Waste Manag ; 116: 147-156, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32799096

RESUMO

This paper reports a complete characterization of the lowest fractions of bottom ash derived from co-combustion of municipal solid waste with sewage sludge (COBA), with the aim to suggest suitable reuse strategies of this by-product. X-Ray Microanalysis is coupled with mineralogical characterization, based on X-Ray Diffraction and Rietveld refinement, to extract information about COBA crystalline and amorphous phases. The composition of different particle size fractions shows that amount of amorphous increases with the increase of fractions sizes. In particular, the finest COBA size fraction (<300 µm) shows more leachable heavy metals (i.e. Pb, and Zn) compared to the investigated fraction with the highest sizes (1400 µm). On the basis of their composition, lowest particle size fractions show a better hydraulic behavior compared to bottom ash obtained from incineration of only municipal solid waste, suggesting possible attractive COBA applications, as for example, Portland cement substitution. In addition, COBA with size fractions in the range of 1000-1400 µm are proposed to be used to produce glass and ceramic. Finally, due to its high amount of reactive amorphous phase (about 73% for fraction size of 1400 µm) COBA is used, in combination with other by-products (coal fly ash and flue gas desulphurization residues), to stabilize municipal solid waste incinerator fly ash produced at the same incinerator plant, following the azure chemistry principle of use a waste to stabilize another waste.


Assuntos
Cinza de Carvão , Metais Pesados , Incineração , Esgotos , Resíduos Sólidos/análise
18.
Waste Manag ; 116: 91-99, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32799100

RESUMO

Co-combustion was proposed as an effective and complementary means for the co-treatment of low rank coal semicoke (LRCS) and oil sludge. The combustion, kinetics and gaseous pollutants emission characteristics during co-combustion of LRCS and oil sludge were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). Results showed oil sludge had more complex weight loss characteristics than LRCS. Proper addition of oil sludge could effectively improve the ignition, burnout and comprehensive combustion performance of blends and 60% was a recommended oil sludge blend ratio. High heating rates could also enhance the combustion performance of blends. The activation energy determined by Coats-Redfern method gradually decreased with the increase of oil sludge blend ratio. DAEM kinetic analysis results showed the maximum activation energy of 113.4 kJ/mol was obtained when conversion rate was 0.4 due to the poor ignition performance of LRCS. All of the CO, CO2, NOx and SO2 emission gradually decreased with the increasing oil sludge blend ratio. LRCS had suppression effect on NOx emission during co-combustion while oil sludge was just the opposite. The low sulfur release rate of oil sludge resulted in the decreasing SO2 emission of blends although oil sludge had promotion effect on SO2 emission.


Assuntos
Carvão Mineral/análise , Esgotos , Gases , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
19.
Sci Total Environ ; 739: 139845, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32758935

RESUMO

The CO2 concentration in the atmosphere is increasing and threatening the earth's climate. Selective CO2 capture at large point sources will help to reduce the CO2 emissions to the atmosphere. Biochar with microporous structure could be a potential material to capture CO2. The impact of feedstock type, pyrolysis temperature and steam activation of biochars were evaluated for CO2 adsorption capacity. Pine sawdust biochars were produced at 550 °C, and steam activated for 45 min at the same temperature after completing the pyrolysis (PS550 and PSS550). Paper mill sludge biochars were produced at 300 and 600 °C (PMS300 and PMS600). The CO2 adsorption capacity of biochars was tested at 25 °C using a volumetric sorption analyzer. Pine sawdust biochars showed significantly higher CO2 adsorption capacity than paper mill sludge biochars due to high surface area and microporosity. Pine sawdust biochars were then evaluated for dynamic adsorption under representative post-combustion flue gas concentration conditions (15% CO2, 85% N2) using a breakthrough rig. Both materials showed selective CO2 uptake over N2 which is the major component along with CO2 in flue gas. PSS550 had slightly higher CO2 adsorption capacity (0.73 mmol g^-1 vs 0.67 mmol g^-1) and CO2 over N2 selectivity (26 vs 18) than PS550 possibly due to increase of microporosity, surface area, and oxygen containing basic functional groups through steam activation. Pine sawdust biochar is an environmentally friendly and low-cost material to capture CO2.


Assuntos
Dióxido de Carbono , Esgotos , Adsorção , Carvão Vegetal , Porosidade
20.
Sci Total Environ ; 739: 140128, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32758956

RESUMO

The long start-up time and facile biomass loss of aerobic granular sludge (AGS) impede its application for actual wastewater treatment. The present study investigates a novel assist-aggregation strategy based on Aspergillus tubingensis (AT) mycelium pellets to accelerate sludge granulation, and engineered Fe3O4 nanoparticles (NPs) were used to further enhance flocculent sludge (FS) aggregation. The AT mycelium pellets, modified by 0.5 g/L Fe3O4@SiO2-QC NPs (AT-V), had a more compact internal structure than the unmodified group (AT-I). The content of extracellular polymeric substances (EPS) and the zeta potential values were observed to increase from 39.86 mg/gVSS and -9.19 mv for AT-I to 69.64 mg/gVSS and 2.35 mv for AT-V, respectively. In optimized cultivation conditions, the aggregated sludge biomass of AT-V reached 1.54 g/g. An original AT-based AGS (AT-AGS) with a high biological activity (64.45 mgO2/gVSS·h as specific oxygen uptake rate) and enhanced velocity (58.22 m/h) was developed in only 9 days. The removal efficiencies of total nitrogen (TN) and total phosphorus (TP) of the AT-AGS were 12.24% and 16.29% higher than those of the inoculated FS under high feeding load. Additionally, the analysis of cyclic diguanylate (c-di-GMP) and con-focal microscope images implied that polysaccharide (PS) of EPS played an important role in maintaining the stability of the AT-AGS. Finally, the dominant functional species contributing to sludge aggregation and pollutants removal of the AT-AGS showed a larger richness and diversity than those of the inoculated FS. This study might provide a novel high-efficiency strategy for the fast formation of AGS.


Assuntos
Esgotos , Águas Residuárias , Aerobiose , Aspergillus , Reatores Biológicos , Nitrogênio , Dióxido de Silício , Eliminação de Resíduos Líquidos
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