The behaviors of the Macrolide-Lincosamide-Streptogramin (MLS) resistance genes were investigated in an anaerobic-aerobic pilot-scale system treating spiramycin (SPM) production wastewater. After ...screening fifteen typical MLS resistance genes with different mechanisms using conventional PCR, eight detected genes were determined by quantitative PCR, together with three mobile elements. Aerobic sludge in the pilot system exhibited a total relative abundance of MLS resistance genes (per 16S rRNA gene) 2.5 logs higher than those in control samples collected from sewage and inosine wastewater treatment systems (P < 0.05), implying the presence of SPM could induce the production of MLS resistance genes. However, the total relative gene abundance in anaerobic sludge (4.3 × 10−1) was lower than that in aerobic sludge (3.7 × 100) despite of the higher SPM level in anaerobic reactor, showing the advantage of anaerobic treatment in reducing the production of MLS resistance genes. The rRNA methylase genes (erm(B), erm(F), erm(X)) were the most abundant in the aerobic sludge (5.3 × 10−1–1.7 × 100), followed by esterase gene ere(A) (1.3 × 10−1) and phosphorylase gene mph(B) (5.7 × 10−2). In anaerobic sludge, erm(B), erm(F), ere(A), and msr(D) were the major ones (1.2 × 10−2–3.2 × 10−1). These MLS resistance genes (except for msr(D)) were positively correlated with Class 1 integron (r2 = 0.74–0.93, P < 0.05), implying the significance of horizontal transfer in their proliferation.
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•SPM wastewater treatment system showed high abundances of MLS resistance genes.•Less MLS resistance genes were found in anaerobic sludge than aerobic sludge.•The most abundant MLS resistance genes were positively correlated with intI1.•Anaerobic and aerobic sludge showed different phylogenetic distributions of ere(A).
A solar photo-Fenton process combined with a biological nitrification and denitrification system is proposed for the decontamination of a landfill leachate in a pilot plant using photocatalytic ...(4.16 m
2 of Compound Parabolic Collectors – CPCs) and biological systems (immobilized biomass reactor). The optimum iron concentration for the photo-Fenton reaction of the leachate is 60 mg Fe
2+ L
−1. The organic carbon degradation follows a first-order reaction kinetics (
k = 0.020 L kJ
UV
−1,
r
0 = 12.5 mg kJ
UV
−1) with a H
2O
2 consumption rate of 3.0 mmol H
2O
2 kJ
UV
−1. Complete removal of ammonium, nitrates and nitrites of the photo-pre-treated leachate was achieved by biological denitrification and nitrification, after previous neutralization/sedimentation of iron sludge (40 mL of iron sludge per liter of photo-treated leachate after 3 h of sedimentation). The optimum C/N ratio obtained for the denitrification reaction was 2.8 mg CH
3OH per mg N–NO
3
−, consuming 7.9 g/8.2 mL of commercial methanol per liter of leachate. The maximum nitrification rate obtained was 68 mg N–NH
4
+ per day, consuming 33 mmol (1.3 g) of NaOH per liter during nitrification and 27.5 mmol of H
2SO
4 per liter during denitrification. The optimal phototreatment energy estimated to reach a biodegradable effluent, considering Zahn–Wellens, respirometry and biological oxidation tests, at pilot plant scale, is 29.2 kJ
UV L
−1 (3.3 h of photo-Fenton at a constant solar UV power of 30 W m
−2), consuming 90 mM of H
2O
2 when used in excess, which means almost 57% mineralization of the leachate, 57% reduction of polyphenols concentration and 86% reduction of aromatic content.
► The solar photo-Fenton process was found to be very efficient in the treatment of leachates, enhancing the biodegradability of the leachate and making possible a subsequent treatment by a biological oxidation process. ► Solar energy is an important natural resource and using it in advanced oxidation processes is probably one of the best ways to make the detoxification of leachates from sanitary landfills economically attractive. ► Biological nitrogen removal was achieved by a by two-step process: aerobic nitrification of ammonia to nitrite and then to nitrate followed by anoxic denitrification of nitrate to nitrite, nitric oxide, nitrous oxide and nitrogen gas using an external carbon source.
This work proposes an integrated leachate treatment strategy, combining a solar photo-Fenton reaction, to enhance the biodegradability of the leachate from an aerated lagoon, with an activated sludge ...process, under aerobic and anoxic conditions, to achieve COD target values and nitrogen content according to the legislation. The efficiency and performance of the photo-Fenton reaction, concerning a sludge removal step after acidification, defining the optimum phototreatment time to reach a biodegradable wastewater that can be further oxidized in a biological reactor and, activation sludge biological process, defining the nitrification and denitrification reaction rates, alkalinity balance and methanol dose necessary as external carbon source, was evaluated in the integrated system at a scale close to industrial. The pre-industrial plant presents a photocatalytic system with 39.52 m2 of compound parabolic collectors (CPCs) and 2 m3 recirculation tank and, an activated sludge biological reactor with 3 m3 capacity.
Leachate biodegradability enhancement by means of a solar driven photo-Fenton process was evaluated using direct biodegradability tests, as Zahn–Wellens method, and indirect measure according to average oxidation state (AOS), low molecular carboxylic acids content (fast biodegradable character) and humic substances (recalcitrant character) concentration. Due to high variability of leachate composition, UV absorbance on-line measurement was established as a useful parameter for photo-Fenton reaction control.
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•Pre-industrial plant for leachate treatment using chemical and biological systems.•Leachate biodegradability enhancement using a solar photo-Fenton reaction.•Nitrogen removal using biological nitrification and denitrification processes.
In Mexico, mezcal production generates huge amounts of vinasses (mezcal vinasses) that cause negative environmental impacts. Thus, mezcal vinasses treatment is necessary before discharging to water ...bodies. Although there is no information for mezcal vinasses, similar effluents have been treated by biological processes (i.e., anaerobic and aerobic), usually complemented by oxidative chemical pretreatments (ozonation) and physicochemical methods. In this work, mezcal vinasses were first ozonated and then subjected to batch aerobic biological degradation. In the ozonation stage, organic matter removals were 4.5 to 11 % as COD, whereas the removal of aromatic compounds and phenols was 16 to 32 % and 48 to 83 %, respectively. In aerobic post-treatment, COD depletions up to 85% were achieved; removals in ozone-pretreated vinasses were higher (80–85 %) than those in raw vinasse (69 %). It seems that ozonation preferentially attacked the recalcitrant fraction of organic matter present in the vinasses and increased its aerobic biodegradability.
According to the characteristics of aniline dyeing wastewater, aerobic biological treatment was adopted herein, and high-throughput sequencing technology was used to analyze the changes to the ...microbial community structure and diversity in the aerobic sludge acclimation stage. As a result, according to the experimental study on the effects of different biomass, the initial pH value and the salinity with the aerobic biological treatment, the chemical oxygen demand (COD) degradation rate can increase linearly with the increase in biomass under different biomass conditions. The organic matter degradation rate is 6.24 mg/L COD·h−1·(mg/L·MLSS)−1, with a correlation coefficient (R2) of 0.98704. When the initial pH value is less than 7.0 ± 0.2, the COD degradation rate increases with the increase in the initial pH value and then decreases gradually. The optimal sludge concentration is 4 g/L; the optimal initial pH value is in the range of 7.0–8.0; the optimal salinity is 1.7%. When the initial concentration of COD is 3000 mg/L, the COD value gradually stabilizes and decreases to 1500 mg/L after 32 h, the degradation rate reaches 50%, and the pH decreases from 7.5 to 4.5. Sphingopyxis has been detected in sludge samples from the third cycle of acclimation, which can biodegrade aromatic compounds, anthraquinone dyes, and their intermediates, and the relative abundance of Sphingopyxis increased from 0.18% to 5.08%, indicating a potential biodegradation ability of aniline dyeing wastewater.
There is increasing concern about chemical pollutants that have the ability to mimic hormones, the so-called endocrine-disrupting compounds (EDCs). One of the main reasons for concern is the possible ...effect of EDCs on human health. EDCs may be released into the environment in different ways, and one of the most significant sources is industrial wastewater. The main objective of this research was to evaluate the treatment performance of different wastewater treatment procedures (biological treatment, filtration, advanced oxidation processes) for the reduction of chemical oxygen demand and seven selected EDCs (dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, bisphenol A and nonylphenol) from wastewaters from a mill producing 100 % recycled paper. Two pilot plants were running in parallel and the following treatments were compared: (i) anaerobic biological treatment followed by aerobic biological treatment, ultrafiltration and reverse osmosis (RO), and (ii) anaerobic biological treatment followed by membrane bioreactor and RO. Moreover, at lab-scale, four different advanced oxidation processes (Fenton reaction, photo-Fenton reaction, photocatalysis with TiO₂, and ozonation) were applied. The results indicated that the concentrations of selected EDCs from paper mill wastewaters were effectively reduced (100 %) by both combinations of pilot plants and photo-Fenton oxidation (98 %), while Fenton process, photocatalysis with TiO₂ and ozonation were less effective (70 % to 90 %, respectively).
Background
Biological treatment technology is good for the recovery of resources and energy from municipal solid waste (MSW) and cutting down biodegradable components in landfill waste. Recently, the ...aerobic biological treatment of MSW has increased in rural areas of China. These facilities are usually open setup and close to nearby residents, and complaints tend to be received regarding odorous gases. A semi-in-vessel setup facility was built in recent years, and its impact on the environment and personnel is not clear.
Results
Ammonia was the predominant compound released from the windrow and its concentration was one order of magnitude higher than those of other compounds. Terpenes and reduced sulfur compounds (RSCs) persisted throughout the entire active fermentation process, with only slight decreases. The biofilter pool had a greater odor impact on the surrounding neighborhood than the waste unloading and sorting operation. The concentrations of most compounds were reduced by the biofilter pool. Ten major substances that caused odors at the facility were analyzed, where most comprised RSCs. The odor impact of the facility was low, but it was associated with a carcinogenic risk to the operators, thereby indicating the need to improve personal protection.
Conclusions
Large amounts of ammonia and volatile organic compounds were released from the composting units, but they had a low odor impact on the environment because of the semi-in-vessel setup. The odor impact of the facility was low but it was associated with a carcinogenic risk to the operators. This technology can be popularized in rural areas.
A two stage sequential Photo-Fenton’s oxidation followed by aerobic biological treatment using two white rot fungi
P. ostreatus
IBL-02 (PO) and
P. chrysosporium
IBL-03 (PC) was performed to check ...decolorization and to enhance mineralization of azo dye Reactive Blue 222 (RB222). In the first stage, selected dye was subjected to Photo-Fenton’s oxidation with decolorization percentage ≈90 % which was further increased to 96.88 % and 95.23 % after aerobic treatment using two white rot fungi
P. ostreatus
IBL-02 (PO) and
P. chrysosporium
IBL-03 (PC), respectively. Mineralization efficiency was accessed by measuring the water quality assurance parameters like COD, TOC, TSS and Phenolics estimation. Reduction in COD, TOC, TSS and Phenolics were found to be 95.34 %, 90.11 %, 90.84 % and 92.22 %, respectively in two stage sequential processes. The degradation products were characterized by UV–visible and FTIR spectral techniques and their toxicity was measured. The results provide evidence that both fungal strains were able to oxidize and mineralize the selected azo dye into non-toxic metabolites.
Thermal Effects Ye, Jie; Zhang, Panyue; Zeng, Guangming ...
Water environment research,
October 2014, Letnik:
86, Številka:
10
Journal Article
Recenzirano
This review is on the research literature published in 2013 on topics relating to thermal effects in water pollution control. The review is divided into the following sections: membrane preparation ...and separation, adsorbent preparation and adsorption process, aerobic biological treatment, anaerobic biological treatment, natural treatment, resource recover and water environment.
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