This study tracked five pharmaceutically active compounds (PhACs) in Mexico City's sewage, namely, famotidine, indomethacin, dexamethasone, azithromycin, and ivermectin, which were used to treat ...COVID-19. The monitoring campaign was carried out over 30 months (May 2020 to November 2022), covering the five COVID-19 waves in Mexico. In the Central Emitter, the main sewage outflow, famotidine displayed levels of 132.57 ± 28.16 ng L−1 (range from < LOQ to 189.1 ng L−1), followed by indomethacin (average 672.46 ± 116.4 ng L−1, range from 516.7 to 945.2 ng L−1), dexamethasone (average 610.4 ± 225.7 ng L−1, range from 233.4 to 1044.5 ng L−1), azithromycin (average 4436.2 ± 903.6 ng L−1, range from 2873.7 to 5819.6 ng L−1), and ivermectin (average 3413.3 ± 1244.6 ng L−1, range from 1219.8 to 4622.4 ng L−1). The concentrations of dexamethasone, azithromycin and ivermectin were higher in sewage from a temporary COVID-19 care unit, by a factor of 3.48, 3.52 and 2.55, respectively, compared with those found in municipal wastewater. In the effluent of the Atotonilco Wastewater Treatment Plant (AWWTP), which treats near 60 % of the Mexico City's sewage, famotidine was absent, while concentrations of indomethacin, dexamethasone, azithromycin and ivermectin were 78.2 %, 76.7 %, 74.4 %, and 88.1 % lower than those in the influent, respectively. The occurrence of PhACs in treated and untreated wastewater resulted in medium to high environmental risk since Mexico City's wastewater is reused for irrigation in the Mezquital Valley. There, PhACs were found in irrigation canals at lower levels than those observed in Mexico City throughout the monitoring. On the other hand, famotidine, indomethacin, and dexamethasone were not found in surface water resulting from the infiltration of wastewater through soil in Mezquital Valley, while azithromycin and ivermectin sporadically appeared in surface water samples collected through 2021. Using an optimized risk assessment based on a semi-probabilistic approach, the PhACs were prioritized as ivermectin > azithromycin > dexamethasone > famotidine > indomethacin.
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•COVID-19 drugs tracked in Mexico City's sewage throughout the pandemic.•High levels of dexamethasone, azithromycin and ivermectin found through the survey.•Azithromycin and ivermectin levels in sewage fit with COVID-19 five waves in Mexico City.•Mexico City exported COVID-19 drugs to Mezquital Valley through sewage during the pandemic.•Ivermectin, dexamethasone and azithromycin were priority pollutants based on risk assessment.
Municipal sewage sludge is rich in phosphorus, the conversion of which into phosphorus-enriched biochar via microwave-assisted pyrolysis (MWAP) can realize the efficient treatment of municipal sewage ...sludge and the recycling of phosphorus. This follows the concepts of the sustainable development of waste management and “cleaner production”. At present, fundamental knowledge is lacking on the use of MWAP to recover phosphorus from municipal sewage sludge. In this study, the effect of MWAP parameters (temperature, power, and residence time) and additives on the properties of phosphorus-enriched biochar and the migration and transformation of phosphorus were investigated. The pH, surface area, and total phosphorous increased with increasing temperature and power, whereas a greater residence time promoted the conversion of non-apatite inorganic phosphorus (NAIP) into apatite inorganic phosphorous (AP). CaO addition promoted the conversion of NAIP into AP, whereas MgCl2 promoted the conversion of AP into NAIP. The simultaneous addition of CaO and MgCl2 led to antagonism, with CaO being dominant, demonstrating that the original phosphorus components prefer to combine with CaO. Phosphorus recovery was optimal at temperatures 500–600 °C and a residence time of 150 min. The addition of 9% CaO or 6% CaO +6% MgCl2 was sufficient to convert sewage sludge into phosphorus into AP. Under such conditions, AP contents in phosphorus-enriched biochar increased 1.4 times compared to that of additive-free biochar. Our study highlights the potential of MWAP for closing the phosphorus cycle and for producing fertilizers from complex materials, such as municipal sewage sludge.
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•MWAP is an effective method to recover P from municipal sewage sludge.•High-efficiency recovery of P could realize at lower temperature than incineration.•The enrichment ratio of P can reach as high as 98.50%.•CaO and MgCl2 exhibit antagonism when added at the same time.•9% CaO or 6%CaO+6%MgCl2 could improve the content of AP (1.4 times) in 500 °C.
Waste management to reduce the loss of natural resources has become a basis of sustainable development and a circular economy. When using waste, the heavy metal (HM) concentration must be taken into ...account since HMs can be potentially released to the environment, posing a toxicity threat. The aim of the study was thus to estimate the availability for plants of Cr, Ni, Cu, Zn, Cd, and Pb introduced into the soil with waste. We hypothesized that the prepared waste mixtures containing coal or biomass ash and municipal sewage sludge would reduce the environmental risk compared to the studied waste used separately. The research was conducted during a 6-year field experiment with grasses and legumes. HM concentration in soil, waste, and plant biomass; tolerance index; and uptake of HMs by plants were measured. The ash–sludge mixtures had a more favourable effect on the soil in terms of pHKCl, TOC, total nitrogen, and total exchangeable bases than the waste used separately. This provided beneficial conditions for plant growth and development. Consequently, the ash–sludge mixtures increased the plant yield as compared to ash alone, while the mixture containing the biomass ash also enhanced the yield in relation to the sewage sludge. The study showed that the mixtures allowed for a reduction of environmental risk arising from the HM input with waste to the soil. It was proven that HM availability for plants could be beneficially modified by mixing waste. Combining the coal ash with the sewage sludge is particularly recommended, owing to the unfavourable properties of coal ash for plants. The application of the higher dose of the coal ash–sludge mixture showed a better effect than the lower dose, while the influence of both doses of the biomass ash–sludge mixture was similar. Under the ash–sludge treatment, plants took up more HM than under the ash used separately, and the HM concentration in the obtained biomass did not generally exceed that observed under single wastes. This should reduce the accumulation of HMs in the soil during a long-term use of the waste and facilitates the utilisation of the produced biomass.
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•Coal or biomass ash, and municipal sewage sludge were used separately or as mixtures.•Ash-sludge mixtures had more favourable effect on soil than waste used separately.•Heavy metal uptake under waste mixtures was higher than with ash used separately.•Heavy metal content in plants under the mixtures was not higher than with single waste.•Waste mixtures tested can be recommended in reclamation strategies including plants.
Using biochar derived from municipal sewage sludge (MSS) pyrolysis as a catalytic pyrolysis catalyst can not only achieve product recycling but also enhance conversion rate. In this study, the ...kinetics of MSS product recirculation catalytic pyrolysis were investigated based on non-isothermal thermogravimetric experiments. The results demonstrate that MSS noncatalytic/catalytic pyrolysis reaction involves five stages, with the main decomposition occurring between 180 and 680 °C and accounting for 53.14%–69.75% of the total mass loss. 20%-cata and 30%-cata reduced the average activation energy by 24.14% and 44.73% for the noncatalytic pyrolysis of MSS, respectively, and the catalytic effect of sludge-based biochar (S–C) allowed the appearance of the lowest activation energy earlier. MSS noncatalytic pyrolysis follows a kinetic mechanism of random nucleation and nucleation growth, whereas exponential nucleation predominate in catalytic pyrolysis. The catalysis mainly operates on macromolecular fracture breakdown and tar secondary cracking. Moreover, a plausible catalytic mechanism for MSS product recirculation catalytic pyrolysis was proposed. The results are expected to be useful in the design of efficient pyrolysis systems.
Sludge reuse and utilization is one of important routines of disseminating fecal pollution to surface water and groundwater. However, it remains unclear the spatial distribution of fecal pollution ...indicators in sludge flocs and their reductions during sludge treatment processes. In this study, the abundances of fecal pollution indicators including cross-assembly phage (crAssphage), JC and BK polyomavirus (JCPyV, BKPyV), human adenovirus (HAdV), the human-specific HF183 Bacteroides (HF183) and Escherichia coli (EC) in soluble extracellular polymeric substances (S-EPS), loosely-bound EPS (LB-EPS), tightly-bound EPS (TB-EPS), and pellets of sludge flocs were determined, and the effect of potassium ferrate (PF) treatment on their removal and inactivation was investigated by using both qPCR and viability-qPCR. Results showed that all investigated indicators were detected in each fraction of sludge flocs. The PF treatment led to a great migration of indicators from sludge pellets to sludge EPS and some extent of their inactivation in each fraction of sludge flocs. The overall reductions of human fecal indicators in sludge determined by qPCR were 0–1.30 logs, which were 0–2 orders of magnitude lower than those of 0.69–2.39 logs detected by viability-qPCR, implying their inactivation by PF treatment to potentially alleviate the associated human health risks.
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•Spatial distribution of fecal indicators in sludge flocs was revealed.•Higher abundances of fecal indicators existed in pellets of thickened sludge.•PF treatment of thickened sludge led to indicator migration from pellets to EPS.•Fecal indicators in pellets and EPS can be inactivated by PF treatment.•PF treatment reduced the human fecal pollution in thickened sewage sludge.
•Anammox bacteria were adapted to low t by gradual acclimation and cold shocks.•The shocked culture was more active than gradually acclimated culture.•N-respiration protein content decreased in ...gradually acclimated bacteria.•Several cold shock proteins were upregulated more efficiently by cold shocks.•At ↓T, anammox adjusted ladderane membrane lipid composition in three aspects.
Anammox bacteria enable efficient removal of nitrogen from sewage in processes involving partial nitritation and anammox (PN/A) or nitrification, partial denitrification, and anammox (N-PdN/A). In mild climates, anammox bacteria must be adapted to ≤15 °C, typically by gradual temperature decrease; however, this takes months or years. To reduce the time necessary for the adaptation, an unconventional method of ‘cold shocks’ is promising, involving hours-long exposure of anammox biomass to extremely low temperatures. We compared the efficacies of gradual temperature decrease and cold shocks to increase the metabolic activity of anammox (fed batch reactor, planktonic “Ca. Kuenenia”). We assessed the cold shock mechanism on the level of protein expression (quantitative shot-gun proteomics, LCHRMS/MS) and the structure of membrane lipids (UPLCHRMS/MS). The shocked culture was more active (0.66±0.06 vs 0.48±0.06 kg-N/kg-VSS/d) and maintained the relative content of N-respiration proteins at levels consistent levels with the initial state, whereas the content of these proteins decreased in gradually acclimated culture. Cold shocks also induced a more efficient expression of potential cold shock proteins (e.g. ppiD, UspA, pqqC), while putative cold shock proteins CspB and TypA were upregulated in both cultures. Ladderane lipids characteristic for anammox evolved to a similar end-point in both cultures; this confirms their role in anammox bacteria adaptation to cold and indicates a three-pronged adaptation mechanism (ladderane alkyl length, introduction of shorter non-ladderane alkyls, polar headgroup). Overall, we show the outstanding potential of cold shocks for low-temperature adaptation of anammox bacteria and provide yet unreported detailed mechanisms of anammox adaptation to low temperatures.
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This study proposed a novel one-stage plug-flow microaerobic sludge blanket (PMSB) with membrane aerated for treating low carbon to nitrogen (C/N) ratio municipal sewage. The performance of ...simultaneous nitrification, denitrification, and anammox in the reactor was investigated. The results illustrated that the removal efficiencies of ammonium and total nitrogen (TN) were 93.2% and 87.1% with a C/N ratio of 4. High throughput sequencing revealed that aerobic bacteria, anaerobic bacteria and facultative anaerobe could co-exist at the same time in the sludge blanket. Meanwhile, a notable correlation between the oxygen concentration and the distance of the membrane module was analyzed. It was shown that the microbial community of functional bacteria developed in different aeration sites due to the oxygen concentration gradient. Microbial community structure was analyzed depending on the sludge stratification in the sludge blanket.
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•A novel plug-flow membrane-aerated process was proposed at low C/N ratio.•The average removal efficiencies of ammonium and TN were 93.2% and 87.1% at the C/N ratio of 4.•The nutrient removal functional bacteria coexisted in the sludge blanket.•Microbial community structure was analyzed depending on the sludge stratification and DO gradient.
Innovative measure is a urgent requirement for managing the huge volume of municipal sewage sludge. The hydrothermal carbonation （HTC） shows some potential advantages for using hydrochar as a soil ...conditioner. The aim of this work was to investigate the properties of hydrochars, by means of the HTC of municipal sewage sludge under different temperatures （190 and 260~C） and reaction hours （1, 6, 12, 18 and 24 h）. The HTC led to the decreases of N, O and H contents by more than 54.6, 37.9 and 10.0%, respectively, and slight changes of C content. The Py-GC-MS analysis showed that a large proportion of fatty acids, in particular hexadecanoic acid, transferred into alkenes, olefins and aromatic compounds. The 13C-NMR and fourier transform infrared spectra （FTIR） confirmed the transformation and changes in chemical structure in which hydrochar contained lower oxygen-containing organic C of O-alkyl, carboxylic and carbonyl C and aliphaticity, but higher aromatic C and aromaticity. The rich hydrophobic functions induced in high positive charges in the charred sludge. The HTC facilitated the pore structure development, proved by higher specific surface area and specific pore volume, with a maximum of 17.30 and 0.83 cm^3 g^-1, respectively. The availabilities of N, P and K markedly reduced during HTC treatment. The activities of most heavy metals were depressed though they accumulated in the hydrochar. Further work is required to investigate the values and risk of the charred sludge amended to soil.
Phosphorus and operating temperature not only affect the agglomeration behavior but also the transformation and migration of heavy metals. Accordingly, this study examined the effect of temperature ...and phosphorus in a fluidized bed combustion process to understand the emission and distribution of heavy metals by both experimental and thermodynamic calculations. The experimental results indicated that the sodium-phosphate reactions occur before the sodium-silicate reaction in the solid phase when the ratio of P/Na was 1/2. A low-melting-point sodium phosphate component, such as NaPO3, leads to easier particle agglomeration than Na2O-SiO2. In terms of the emissions of heavy metals, Pb and Cd show a similar trend: both the amount of emission smaller than that without adding phosphorus and the amount of emission share an upward trend with the operating time increased during MSS fluidized bed combustion. However, with the presence of phosphorus, the emission of Cr shows slightly decreased, and then sharply dropped, after that, increasing with operating time increased. Generally speaking, the maximum amount of Pb and Cd emitted was at 900 °C, followed by 800 °C and 700 °C. The higher temperature would promote the volatilization of Pb and Cd to emit. On the other hand, Cr emitted at the beginning tended to increase but later decreases when the temperatures were 700 and 900 °C, which may be due to the emission of Cr being influenced by the different affinities of both Al and Cr, reacting with Na in a fluidized bed incinerator. As for the distribution of heavy metals in the solid phase, a higher concentration of heavy metals was found in both the coarsest and finest particles during the process of agglomeration/defluidization.
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•Effect of agglomeration on heavy metals behavior has been considered.•Effect of phosphorus on heavy metals in gas-solid phase also discussed.•Emission of heavy metals sharply increased after defluidization started.•Phosphorus reduces the emission concentration of Pb and Cd.
Landfill leachate contains dissolved organic matter (DOM) exhibiting high ultraviolet absorbance at 254 nm (UVA254). The UVA254 limits leachate co-treatment with municipal sewage by hindering the ...downstream UV disinfection efficiency at wastewater treatment plants. Here, we alleviated the UVA254 by timing the radiation in a UV/electrooxidation (UV/EO) process to accelerate reactive species formation. At 200 A·m−2, the UV radiation was delayed by 10 min to accumulate 21 mg·L−1 as Cl2, which enhanced the initial radical formation rate by 5.25 times compared with a simultaneous UV/EO. The timed operation increased the steady-state concentrations of ClO• by 700 times to 4.11 × 10−14 M and reduced the leachate UVA254 by 78.2% after 60 min. We identified that aromatic formulas with low oxygen content were susceptible to UV/EO from Fourier-transform ion cyclotron resonance mass spectrometry analysis. The toxicity of the treated leachate and generated byproducts was assessed through specific oxygen uptake rates (SOUR) and developmental assays with Platynereis dumerilii. After quenching the residual chlorine, leachate co-treatment at 3.5% v/v presented minimal toxicological risk. Our findings provide operational insights for applying UV/EO in high UVA254 matrices such as landfill leachate.
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•Timed UV irradiation during electrooxidation (UV/EO) accelerated radical formation•Applying UV/EO at 200 A·m–2 reduced more UV254 absorbance than 300 A·m–2•Modelled steady-state concentrations of ClO• increased by 700 times after 60 min•UV/EO targeted aromatic formulas of high molecular weight and low oxygen content•Co-treatment at 3.5% v/v was ideal after chlorine quenching for acceptable toxicity
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