Chemical Organic Demand Research Articles

Effects of Short Retention Times and Ultrasound Pretreatment on Ammonium Concentration and Organic Matter Transformation in Anaerobic Digesters Treating Sewage Sludge

Anaerobic digestion of sewage sludge is limited at the hydrolysis stage of the process. The goal of this study was to assess the effects of sludge retention times and ultrasound pretreatment on the ammonium concentration and organic matter transformation in anaerobic digesters treating sewage sludge. To achieve this, two laboratory-scale semicontinuous anaerobic digesters were operated for a period of over 70 d, including a control reactor and another fed by pretreated sludge. Both anaerobic systems were fed with mixed sludge (50%/50% primary/secondary treatment) in mesophilic conditions (37 °C), with solid retention times (SRT) of 7.5 d (Phase I) and 3 d (Phase II). The performance of the anaerobic digestion process was assessed in terms of the methane yield and the total and soluble chemical organic demand, total solids, and volatile solids removal. The results showed that the ultrasound pretreatment caused an increase of around 22.2% in CODt removal for an SRT of 7.5 d. Meanwhile, an SRT of 3 d resulted in a decrease of up to 92.4% in CODt removal. The performance in terms of biogas production and organic matter removal was significantly affected by the SRT reduction to 3 d, showing that the process is not viable in these conditions.

Valorization of strawberry extrudate waste: Recovery of phenolic compounds by direct-hydrothermal treatment and subsequent methane production by mesophilic semi-continuous anaerobic digestion

Strawberry extrudate (SE) is an underused by-product from strawberry industry. Recovery of the phenolic compounds present in SE would represent a very interesting valorisation option. Two main challenges need to be solved, firstly, the solubilisation and recovery of the phenolic compounds contained in SE, and, after that, the stabilisation of the resulted de-phenolized SE. The present research evaluates the potential of a biorefinery process combining a hydrothermal pre-treatment, followed by a phenolic extraction process and, finally, the anaerobic digestion of the remaining SE for producing energy that will contribute to compensate the energy requirements of the whole system. Following the hydrothermal pre-treatment at 170 °C for 60 min, an extraction of 0.6 ± 0.1 g of gallic acid per kilogram of SE was achieved using an adsorbent resin, representing a recovery rate of 64 %. Long-term semi-continuous anaerobic digestion of de-phenolized SE was evaluated at different organic loading rates to evaluate the stability of the process. The anaerobic digestion of pre-treated SE achieved a stable methane production value of 243 ± 34 mL CH4·g volatile solids−1·d−1 at an organic loading rate (ORL) of 1.25 g volatile solids·L−1·d−1. During the operation at this ORL, the control parameters including pH, alkalinity, soluble chemical organic demand (sCOD), and volatile fatty acid (VFA) remained stable and consistently constant. Specifically, the VFA in the reactor during this stable period achieved a value of 102 ± 128 mg O2/L. Also, an economic balance showed that the minimal price of the generated phenolic extract for having benefited from the proposed biorefinery system was 0.812 €·(g of gallic acid equivalents)−1, a price within the range of phenolic compounds used in the food industry.

Performance of a Full-Scale Vermifilter for Sewage Treatment in Removing Organic Matter, Nutrients, and Antibiotic-Resistant Bacteria

The vermifilter (VF) is regarded as a sustainable solution for treating rural sewage. However, few studies have investigated the performance of a full-scale vermifilter. The objective of this study is to evaluate the performance of a full-scale vermifilter in reducing organic matter, nutrients, and antibiotic-resistant bacteria contained in sewage. Influent and effluents were obtained from a rural sewage treatment plant using a VF and UV disinfection system. The results show a significant removal (p < 0.05) of chemical organic demand (COD) (77%), biochemical oxygen demand (BOD5) (84%), total nitrogen (TN) (53%), and total phosphorus (36%). Seasonality is an influential variable for COD, BOD5, and TN removal. In addition, the molecular weight distribution shows that the VF does not generate a considerable change in the distribution of organic matter (COD and total organic carbon (TOC)) and NH4+-N. The UV disinfection system eliminated 99% of coliform bacteria; however, they are not eliminated to safe concentrations. Therefore, it is possible to detect bacteria resistant to the antibiotics ciprofloxacin, amoxicillin, and ceftriaxone at 63.5%, 87.3%, and 63.5%, respectively, which were detected in the effluents. This study shows the potential of a system for the removal of pollution and the need to optimize the VF to be a safe treatment.

Ozonation and Granular Activated Carbon Adsorption for the Removal of Refractory Organic Matter and Decolorization During Wastewater Tertiary Treatment

This study investigated two different hybrid processes for the treatment of municipal secondary-treated biological effluents to meet the reuse of recycled water requirements for organic matter and color. The two hybrid treatment approaches were an oxidation-based treatment process (coagulation–sedimentation–deep-bed filtration [CSDF]–ozone oxidation) and an adsorption-based treatment process (CSDF-granular activated carbon [GAC] adsorption). The efficiencies of ozonation and GAC adsorption in removing chemical organic demand (COD), dissolved organic carbon (DOC), and color intensity were evaluated. The effect of CSDF as the pretreatment was also studied. Ozonation showed a much higher color removal efficiency (88%, 4.7 mg/L ozone dose) than GAC adsorption (23%). Organic matter with an apparent molecular weight of 2–3 kDa, being humus-like, might be the colored fraction in the secondary and CSDF effluents. Ozonation had a stronger ability to remove these substances than GAC adsorption, resulting in a visibly higher color removal efficiency. In addition, higher COD and DOC removal were achieved by ozonation when the average ozone dose was increased to 9.1 mg/L. Although both hybrid processes were reliable for reducing organic matter and color, the results show that ozonation is more suitable for simultaneously removing refractory organic matter and color.

Characteristics of antibiotic resistance gene distribution in rainfall runoff and combined sewer overflow.

Rainfall runoff and combined sewer overflow (CSO) converge with organic waste, nutrients, and microbes from the ground and wastewater. These pollutants promote the spread and transformation of antibiotic resistance genes (ARGs). In this study, four rainfall runoff and one CSO outfall were chosen, and samples were collected to explore the occurrence and distribution of ARGs. The ARGs were extracted from suspended solids and analyzed using metagenomic sequencing. A total of 888 ARG subtypes, belonging to 17 ARG types, were detected in all samples. Eleven ARG types were shared by all the samples. Multidrug resistance genes had the highest relative abundance. Their total relative abundance reached 1.07 ratio (ARG copy number/16S rRNA gene copy number) and comprised 46.6% of all the ARGs. In all samples, the CSO outfall had the highest total relative abundance (8.25 × 10-1 ratio) of ARGs, with a ratio ranging ND (not detected)-3.78 × 10-1 ratio. Furthermore, the relationship between ARG types and environmental factors was determined using redundancy analysis. The results showed that chemical organic demand (COD) and bacterial abundance were positively correlated with most ARG types, including multidrug, bacitracin, aminoglycoside, β-lactam, tetracycline, and sulfonamide. NH3-N, TN, and TP were positively correlated with rifamycin, fosmidomycin, and vancomycin resistance genes. The relationship among the ARG subtypes was investigated using network analyses. The multidrug resistance gene subtypes had the highest frequency of co-occurrence. This study provides insights into the occurrence and distribution of ARGs under non-point source pollution and may contribute to the control of ARGs.

Simultaneous partial nitritation, anammox, and denitrification process for the treatment of simulated municipal sewage in a single-stage biofilter reactor

This study provides a feasible scheme for the treatment of municipal sewage through simultaneous partial nitritation, anammox, and denitrification (SNAD) process, which was realized in a single-stage biofilter reactor (BFR). First, the BFR was started up to enrich the anaerobic ammonium-oxidizing bacteria (AnAOB) in the upper part of the reactor through the operation mode of the top influent and bottom effluent. Then, the BFR was inoculated with activated sludge and aerated continuously at the bottom to realize the coupling of SNAD, which was accompanied by a two-point influent from the bottom and top effluent. Results indicated that the high removal efficiency of NH4+-N (93.40%), total nitrogen (TN, 89.95%), and soluble chemical oxygen demand (SCOD, 92.68%) were achieved with an air–water ratio of 4.29 and hydraulic retention time (HRT) of 6 h. During the SNAD steady phase for the treatment of simulated municipal sewage with a soluble chemical organic demand to nitrogen (C/N) ratio of 2.31, low concentrations of NH4+-N (4.13 mg/L), TN (6.44 mg/L), and SCOD (11.29 mg/L) were attained in the effluent. High-throughput sequencing analysis indicated that the relative abundance of Nitrosomonas, Candidatus Brocadia, and Denitratisoma were 0.77%, 0.43%, and 4.07% in the biofilm at the 0–12.5 cm zone, respectively, suggesting successful implementation of the SNAD process.

Enhancing anaerobic digestion process with addition of conductive materials

Anaerobic digestion is widely used for the treatment of wastewater for its low costs and bioenergy production, but the performances of anaerobic digestion often need improving in practical applications. The addition of conductive materials could lead to direct interspecies electron transfer (DIET) among the anaerobic microorganisms, and consequently enhance the efficiencies of anaerobic digestion. In this paper, the effects of DIET via conductive materials on chemical organic demand (COD) removal, volatile fatty acid (VFA) consumption and methane production were reviewed. The reports on the increase of conductive microorganisms due to the addition of conductive materials were discussed. Results regarding activities of microorganisms and morphology and properties of sludge were described and commented, and future research needs were also proposed which included better understanding of the roles of DIET in each step of anaerobic digestion, mechanisms of metabolism of pollutants in DIET-established systems and inhibition of excessive dosage of conductive materials.

Continuous Anaerobic Treatment of the Aqueous Phase of Hydrothermal Liquefaction from Spirulina Using a Horizontal-Flow Anaerobic Immobilized Biomass (HAIB) Reactor

Anaerobic digestion is a possibility for post-hydrothermal liquefaction wastewater (PHWW) treatment because this wastewater is rich in nutrients and organic compounds. However, the PHWW presents many toxic compounds. A strategy for the anaerobic treatment of toxic compounds is using biomass adhered to inert supports forming biofilms, which can offer more resistance to the microorganism and protection from such compounds. The continuous treatment of PHWW is the essential key to obtaining a sustainable hydrothermal liquefaction process. In this work, the use of immobilized biomass was evaluated for the anaerobic degradation of PHWW from Spirulina in batch assays and continuous treatment. Higher methane production potential and volatile fatty acid mass balance showed the advantages of using biomass immobilized in polyurethane foam. Continuous treatment in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor reached chemical organic demand (COD) removal efficiencies of 67% and 58% for volumetric organic load rates of 0.8 and 1.6 g COD.L−1.d−1, respectively. After 200 days of continuous treatment, Anaerobaculum and Coprothermobacter, fermentative proteolytic genera of bacteria with potential for hydrogen production, were favored.

Hydrodynamics- and hydrochemistry-affected microbial selenate reduction in aquifer: Performance and mechanisms

Selenate [Se(VI)] with higher content in groundwater will be harmful for human beings. Hence, effective treatment for Se(VI) in aquifer should be conducted reasonably. Microbial reduction of Se(VI) to elemental selenium with weak movability and toxicity has attracted significant attention due to its high efficiency and no secondary contamination. However, hydrodynamic and hydrochemical influences with corresponding mechanisms during Se(VI) bioreduction are still not clear. In this study, influences of flow rate, initial Se(VI) and organic concentrations, coexisting nitrate were evaluated. Se(VI) removal efficiency and capacity reached 96.42 ± 6.82% and 41.28 ± 3.41 (g/m3·d) with flow rate of 0.56 mL/min, initial Se(VI) and chemical organic demand concentrations of 10 mg/L and 400 mg/L. Dechloromonas and Pseudomonas were presumably contributed to Se(VI) reduction, with upregulated serA and tatC genes. Solid Se0 was identified as the final product from Se(VI) reduction. These results will be beneficial for the further comprehending of Se(VI) remediation in aquifer.

Rapid aerobic granulation using biochar for the treatment of petroleum refinery wastewater

Aerobic granular sludge technology has great potential for the treatment of petroleum refinery wastewater. However, strategies to shorten the granulation time and improvement the stability still need to be developed. In this work, biochar was prepared from waste petroleum activated sludge (biochar-WPS) and used in a sequencing batch reactor for the treatment of petroleum refinery wastewater. Biochar-WPS presented the surface area of 229.77 m2/g, pore volume of 0.28 cm3/g, H/C and O/C atomic ratios of 0.42 and 0.21, respectively. The porous structure and a high degree of hydrophilicity were found to facilitate microbial colonization and adhesion as well as particle aggregation. Application of biochar-WPS resulted in the formation of more substantial and stable aerobic granules (~ 66% of granules > 0.46 mm diameter) 15 days earlier compared with the control. The addition of biochar-WPS enhanced the average removal efficiency of chemical organic demand (~ 3%), oil (~ 4%) and total nitrogen (~ 10%) over the control. Increased microbial richness and diversity were observed within the formed granules and had an increased (~ 4%) proportion of denitrifying bacteria. These results indicate that an aerobic granulation mechanism using biochar-WPS is a feasible option for the treatment of petroleum refinery wastewater.

Removal of 17α-ethinylestradiol and caffeine from wastewater by UASB-Fenton coupled system

ABSTRACT In aquatic systems, some substances considered as endocrine disruptors have been detected, which can be due to their incomplete elimination in wastewater treatment plants (WWTPs) and inadequate disposal of pharmaceuticals. Among these contaminants are 17α-ethinylestradiol (EE2) and caffeine (CAF). Moreover, it has been reported that this kind of contaminants may provoke different adverse effects in many aquatic organisms. Because of that, in the present study, up-flow anaerobic sludge blanket reactors (UASB) coupled with the Fenton process was evaluated for EE2 and CAF removal spiked in wastewater samples. First, the best reaction conditions were established in each process. For UASB reactor, two hydraulic retention times (HRT 8 and 24 h) were evaluated, achieving the highest chemical organic demand (COD) removal (70 %) and drug elimination (84 %–86 %) with HRT 24 h. Subsequently, Fenton process was conducted at pH 3 with different levels of Fe2+ (0.05–0.5 mmol/L) and molar ratios Fe2+:H2O2 (1:1–1:10). Better results were obtained with 0.5 mmol Fe2+/L, and 1:10 ratio molar Fe2+:H2O2. Finally, UASB-Fenton coupled system allowed 80 % of COD decrease, almost complete removal of drugs and the toxicity of samples on Vibrio fischeri was reduced from 73 % to 30 %, demonstrating that this coupled system is a promising and efficient system for pharmaceutical compounds removal from wastewater.

Molecular weight distribution of the recalcitrant organic matter contained in kraft mill effluents and the identification of microbial consortia responsible for an anaerobic biodegradable fraction

The objective of this research was to evaluate the distribution of the molecular weights of the recalcitrant organic matter contained in kraft mill effluents and identify microbial consortia responsible for an anaerobic biodegradable fraction. As a result, the average removal efficiencies of chemical organic demand (COD) and biological oxygen demand (BOD5) during the entire period of operation were 28% and 53%, respectively. The non-biodegradable organic matter was detected at molecular weights less than 1000 Da. However, most of the organic matter was in the molecular weight fraction higher than 10000 Da with 32 ± 11.6% COD as well as color (42.3 ± 8.7%), total phenolic compounds (35.9 ± 7.9%) and adsorbable organic compounds (AOX) (13.0 ± 2.7%). Methanogenic acetoclastic archaea of the genera Methanomethylovorans and Methanosarcina were found in the surface and middle zones of the reactor. Moreover, Methanosaeta and Methanolinea were identified in the low zone of the reactor. In all zones of the reactor, Desulfomicrobium and Desulfovibrio were found to be the most dominant genera of sulfate-reducing bacteria (SRB).

Synthesis and adsorption properties of activated carbon from KOH-activation of Moroccan Jujube shells for the removal of COD and color from wastewater

<p class="Mabstract">This study aimed to investigate the applicability of new low-cost activated carbon<span style="text-decoration: line-through;">s</span> with a high surface area prepared by KOH chemical activation of jujube shells (denoted JSAC) as adsorbent of Chemical Organic Demand (COD) from wastewater.</p><p>The prepared activated carbon is characterized by various physical-chemical methods to determine their morphological, textural and chemical characterization, including nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Boehm titration method and the pH of the point of zero charge (pH<sub>PZC</sub>).</p><p>Then they were used as an adsorbent for the removal of COD from wastewater collected from Fez area. Adsorption equilibrium and kinetic data were determined and fitted to several adsorption isotherms and kinetics models, respectively. The results showed that the Langmuir isotherm fitted well the equilibrium data of COD on JSAC adsorbent; whereas, the kinetic data were best fitted by the pseudo-second-order model. This adsorbent showed the highest removal efficiency for COD (72%) and the grey colour of the wastewater (83%) for an optimum dose of 0.5 g<sub>JSAC</sub>. L<sup>-1</sup>. Results from the study showed that JSAC activated carbon could be utilized as an effective and less expensive adsorbent for the removal of COD in wastewater.</p>

Synthesis and adsorption properties of activated carbon from KOH-activation of Moroccan Jujube shells for the removal of COD and color from wastewater

This study aimed to investigate the applicability of new low-cost activated carbons with a high surface area prepared by KOH chemical activation of jujube shells (denoted JSAC) as adsorbent of Chemical Organic Demand (COD) from wastewater.The prepared activated carbon is characterized by various physical-chemical methods to determine their morphological, textural and chemical characterization, including nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Boehm titration method and the pH of the point of zero charge (pHPZC).Then they were used as an adsorbent for the removal of COD from wastewater collected from Fez area. Adsorption equilibrium and kinetic data were determined and fitted to several adsorption isotherms and kinetics models, respectively. The results showed that the Langmuir isotherm fitted well the equilibrium data of COD on JSAC adsorbent; whereas, the kinetic data were best fitted by the pseudo-second-order model. This adsorbent showed the highest removal efficiency for COD (72%) and the grey colour of the wastewater (83%) for an optimum dose of 0.5 gJSAC. L-1. Results from the study showed that JSAC activated carbon could be utilized as an effective and less expensive adsorbent for the removal of COD in wastewater.

Electro-Fenton Degradation of Trimellitic and Pyromellitic Acids: Kinetics and Mechanism

This paper describes the application of electro-Fenton technology to decontaminate waters containing trimellitic and pyromellitic acids. In this technique, the electrogeneration of hydroxyl radicals (•OH) leads to the oxidative degradation of the benzene polycarboxylic acids until their total mineralization. The effect of the operating parameters on the trimellitic acid removal was studied. Under the optimal conditions (C0 = 2.10−4 M, [Fe2+] = 0.3 mM, I = 300 mA, [Na2SO4] = 0.05 M, pH = 3), the mineralization of pyromellitic and trimellitic acid solutions was followed by chemical organic demand (COD) measurements after 4 and 5 h of electrolysis time, respectively. The highest disappearance rate of the pyromellitic acid is due to its greater reactivity compared to the trimellitic acid towards the hydroxyl radicals. The products resulting from degradation of pyromellitic acid were identified by using UPLC/MS. The identified by-products allowed proposing a degradation pathway for the pyromellitic and trimellic acids.

Food waste anaerobic digestion of a popular restaurant in Southern Brazil

Abstract Food wastage is a relevant problem all over the world. Remains of prepared foods increase the waste of resources due to energy and labor used in their preparation. However, food waste has a high energy potential can be converted in the form of methane via anaerobic digestion. This study evaluated the potential for recovery of energy contained in food wastes and presented a way to stablish the anaerobic digestion process using solely food waste. For this purpose, a prototype anaerobic digester was used of complete mixture with a volume of 408 L, 15% of total solids, temperature of 29.4 °C and an agitation system. The system was operated at steady state for 51 days in hydraulic retention time of 103 days, volatile solids and chemical oxygen demand of 0.80 g L−1 rd−1. According to the literature, the stabilization period presented typical inconvenient of food wastes digestions processes, that was solved monitoring at more frequent intervals the volatile fatty acids and with the maintenance of a compatible volume of organic load according with the size of the reactor. It was obtained a reduction of 90% in volatile solids and 82% in chemical organic demand. The methane production was 0.51 L.g−1CODc, 0.44 L.g−1VSc and volumetric yield of 0.32 L.L−1rd−1, representing 59% of the composition of the biogas. The adequate levels of agitation frequency, feeding load, temperature and C/N ratio were found in this study using the prototype anaerobic biodigester.

Microbial Desalination Cells with Efficient Platinum‐Group‐Metal‐Free Cathode Catalysts

AbstractAn iron‐nitrogen‐carbon‐based catalyst was used at the cathode of a microbial desalination cell (MDC) and compared with platinum (Pt) and an activated carbon (AC) cathode. The Fe‐N−C catalyst was prepared by using nicarbazin (NCB) as the organic precursor through a sacrificial support method (SSM). Rotating ring disk electrode (RRDE) experiments show that Fe‐NCB had a higher electrocatalytic activity compared to AC and Pt. The utilization of Fe‐NCB in the cathode substantially improved the performance output with an initial maximum power density of 49±2 μW cm−2 in contrast to Pt and AC catalysts, which show lower values of 34±1 and 23.5±1.5 μW cm−2, respectively. After four cycles, Fe‐NCB catalyst lost 15 % of its initial performance, but still was 1.3 and 1.8 times more active than Pt and AC, respectively. Solution conductivity inside the desalination chamber (DC) decreased by 46–55 % with every cycle. The pH of the cathodic chamber and the DC increased to 10–11, owing to the production of OH− during the oxygen reduction reaction and the migration of OH− into the DC. Chemical organic demand decreased by 73–83 % during each cycle. It was shown that Fe‐NCB and Pt had a similar coulombic efficiency (CE) of 39±7 % and 38±2 %, whereas AC had lower CE (24±5 %).

Evaluation of Lemna minor and Chlamydomonas to treat palm oil mill effluent and fertilizer production

Malaysia is considered as one of the major palm oil producers in the world. Therefore, it is important to develop an environmentally friendly and economic method to treat palm oil mill effluent (POME). The main aim of this study was to investigate the potential of Lemna minor (L. minor) and Chlamydomonas incerta (C. incerta) with catalog number (KR349061) for the bioremediation of POME in order to achieve higher water quality standard and further produce organic fertilizer. In this study, three different experiments were conducted by using L. minor, followed by addition of C. incerta, and further combination of L. minor and C. incerta. The concentration of nitrate (NO3−), ammoniacal nitrogen (NH3-N), phosphate (PO4-P), Electrical Conductivity (EC) and salinity in produced fertilizer were measured, and then they were compared with two current commercial fertilizers. Growth factors such as growth rates, average number of leaf and height of root of L. minor of plants were also determined. The results showed that the microalgae and macrophytes were capable of removing only 4.4% of chemical organic demand (COD) whereas the respective maximum removal rates for NO3−, NH3-N, and PO4-P were 12.5%, 11.3%, and 70.47%. Also, the average differences of NO3−, NH3-N, and PO4-P concentrations in produced fertilizer in comparison with two current commercial fertilizers were 95, 39.5, and 62.5mg/g, respectively. The results of this study revealed that only L. minor was converted into fertilizer. This study elaborated that both L. minor and C. incerta are able to remove a part of organic pollutants and nutrients from POME.

Removal of veterinary antibiotics from anaerobically digested swine wastewater using an intermittently aerated sequencing batch reactor

A lab-scale intermittently aerated sequencing batch reactor (IASBR) was applied to treat anaerobically digested swine wastewater (ADSW) to explore the removal characteristics of veterinary antibiotics. The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand (COD) volumetric loadings, solid retention times (SRT) and ratios of COD to total nitrogen (TN) or COD/TN. Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics. Mass balance analysis revealed that greater than 60% of antibiotics in the influent were biodegraded in the IASBR, whereas averagely 24% were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium. Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand (COD) volumetric loadings, which could achieve up to 85.1%±1.4% at 0.17±0.041kgCOD/m-3/day, while dropped to 75.9%±1.3% and 49.3%±12.1% when COD volumetric loading increased to 0.65±0.032 and 1.07±0.073kgCOD/m-3/day, respectively. Tetracyclines, the dominant antibiotics in ADSW, were removed by 87.9% in total at the lowest COD loading, of which 30.4% were contributed by sludge sorption and 57.5% by biodegradation, respectively. In contrast, sulfonamides were removed about 96.2%, almost by biodegradation. Long SRT seemed to have little obvious impact on antibiotics removal, while a shorter SRT of 30–40day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge. Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work.

Biogas production from a native beverage vinasse using a modified UASB bioreactor

This work evaluated the redesign of an Upflow Anaerobic Sludge Blanket (UASB) bioreactor to increase biogas production from anaerobic digestion of vinasse and compared the redesign UASB bioreactor with a conventional UASB design. Vinasse contains a high level of organic matter, 120.2±18.4gO2/L of chemical organic demand (COD), and a 0.8 biodegradability index (BI). Thus, vinasse is a potential nutrient source for biogas production by anaerobic digestion. The modified UASB bioreactor has an innovation that consisted in a second leach bed sludge, which improved the methane proportion in biogas producing 2140mLCH4/day as compared to the traditional bioreactor (1840mLCH4/day).