Biodegradability Index Research Articles

An Examination of Calculations: From Anaerobic Mono-digestion to Co-digestion

Anaerobic digestion is a biochemical process and form of sustainable technology. In comparison to mono-digestion, co-digestion is more effective in the utilization of diverse resources, supply of nutrient balance, and overall digestibility and stability. The co-digestion biodegradability index, co-digestion performance index, and synergistic effect index are generally used as anaerobic metrics to evaluate the co-digestion performance. Although they are numerical parameters, little information on their working procedures has been revealed. There is also a lack of supporting calculations for some published data hence their values cannot be verified. The aim of this article is to reconsider and examine the mathematical calculations from anaerobic mono-digestion to co-digestion. The method of study is a pen-and-paper analysis that processes both experimental and theoretical data from past studies. The article serves four purposes. First, it identifies processing parameters. Second, it shows step-by-step procedures of a series of calculations. Third, it identifies the core parameter in the calculation of anaerobic co-digestion. Fourth, it establishes the relationships between co-digestion biodegradability index, co-digestion performance index, and synergistic effect index. Critically, the mass fraction of volatile solid is identified as the core parameter that determines the valid calculations of co-digestion.

Physico-chemical quality and toxicity of wastewater from Katiola commune (North-Central Côte d’Ivoire)

In Africa in general and in Côte d’Ivoire in particular, the management of wastewater in the context of sanitation is devolved to cities and municipalities. Katiola commune is no exception. In fact, this municipality faces problems with wastewater management. The objective of this study is to evaluate the physicochemical quality and toxicity of wastewater from this municipality with a view to implementing an appropriate management method. Thus, surveys followed by field visits and wastewater sampling were carried out on six (06) sites. The data from the analyzes were compared to the guide values ​​of the WHO, France and Ivory Coast. The results reveal that populations dispose of wastewater using unconventional practices (90%). This wastewater is considerably mineralized (469 and 663 μS/cm), of domestic origin and easily biodegradable (biodegradability index equal to 2.49) with a normal pH. In terms of toxicology, Katiola wastewater is rich in lead (26.9 to 640 µg/L) and nickel (50 to 779.2 µg/L). As for pesticides, beta-endosulfan and endrin have concentrations lower than the limit value set by the French standard, thus meaning a low impact on humans and their environment.

Evaluation of Biochemical Methane Potential and Kinetics of Organic Waste Streams for Enhanced Biogas Production

Organic waste has the potential to produce methane gas as a substitute for petrol-based fuels, while reducing landfilling and possible environmental pollution. Generally, anaerobic digestion (AD) is used only in wastewater treatment plants as a tertiary stage of sewage sludge treatment, generating a fraction of the energy that such process plants require. In this study, four different wastes—food waste (FW), dairy industry waste (DIW), brewery waste (BW), and cardboard waste (CBW)—were tested for biogas production. The biochemical methane potential (BMP) of each sample was evaluated using an automatic methane potential system (AMPTS). Operating parameters such as pH, temperature, total solids, and volatile solids were measured. Experiments on the anaerobic digestion of the samples were monitored under mesophilic conditions (temperature 37 °C, retention time 30 days). Specific methane yields (SMYs), as well as the theoretical methane potential (BMPth), were used to calculate the biodegradability of the substrates, obtaining the highest biodegradability for BW at 95.1% and producing 462.3 ± 1.25 NmL CH4/g volatile solids (VS), followed by FW at an inoculum-to-substrate ratio (ISR) of 2 at 84% generating 391.3 NmLCH4/g VS. The BMP test of the dairy industry waste at an inoculum-to-substrate ratio of 1 was heavily inhibited by bacteria overloading of the easily degradable organic matter, obtaining a total methane production of 106.3 NmL CH4/g VS and a biodegradability index of 24.8%. The kinetic modeling study demonstrated that the best-fitting model was the modified Gompertz model, presenting the highest coefficient of determination (R2) values, the lowest root means square error (RMSE) values for five of the substrates, and the best specific biogas yield estimation with a percentage difference ranging from 0.3 to 3.6%.

Agricultural Valorization of Treated Effluent from Korhogo Wastewater Treatment Plant

Aims: The main objective is to evaluate the effluents of Korhogo’s wastewater treatment plant for irrigation and fertilization in agriculture. Study Design: Characterization of outlet treated wastewaters has been firstly done. Then their suitability for irrigation has been determined and finally their fertilizing power has been assessed. Place and Duration of Study: Department of geosciences, Korhogo’s wastewater treatment plant and laboratory. Sampling and analyses were carried out in January 2023, before agricultural field implementation started in February 2023. Methodology: Firstly, Physico-chemical and microbiological analyses, allowed characterization of outlet treated wastewaters. A determination of their suitability for irrigation was then done through Sodium Adsorption Ratio calculation and water classification with Diagram of Richards. An assessment of their fertilizing capacity was finally carried out using these waters for irrigating and fertilizing crop plots (3x2 m), and consisting of determining firstly their biodegradability index, then their nutrient contents (Nitrogen, Phosphorus and potassium), and the influence of their use on crop development and yield. Results: The results show that several parameters meet standards for discharge of treated wastewater except total nitrogen, suspended matters and total phosphorus (67.67 mg/l, 271.33 mg/l and 18.30 mg/l). Sodium Adsorption Ratio (SAR) value=3.78 and C3S1 class indicate that these treated effluents can be used for irrigation without salinization risk. As fertilizer, treated effluents brought to crops respectively 603 kg/ha of nitrogen, 162 kg/ha of phosphorus and 99 kg/ha of potassium for maize; and 368.5 kg/ha of nitrogen, 99 kg/ha of phosphorus and 60.5 kg/ha of potassium respectively for Okra. A yield of 12.2 kg of fresh maize and 3.15 kg of fresh okra was obtained for the plot irrigated by treated effluents, compared with 4.80 kg of fresh maize and 0.36 kg of fresh okra for the plot irrigated by well water. Conclusion: This study has shown that outlet treated wastewater from Korhogo’s wastewater treatment plant is suitable for crops irrigation, contains sufficient nutrients enhancing crops development and yield.

Enhancing physico-chemical water quality in recycled dairy effluent through microbial consortium treatment

The dairy industry, notorious by generating wastewater rich in organic and nitrogenous content, necessitates sustainable recycling solutions. Biological treatment emerges as a cost-effective and chemical-free alternative. This study delves into the potential of microbial consortium, a microbial consortium, for recycling dairy effluent, aiming at water reclamation and environmental sustainability. Effluent samples from Madurai's Dairy Industry underwent microbial consortium treatment in a recycling prototype, with treatment efficacy assessed through physicochemical parameters and contaminant removal efficiency.Guided by a biodegradability index of 4.51, the study showcased EM's impact, revealing a notable decrease in pH levels, fostering an alkaline environment (2.35 ± 0.06 ppt). Dissolved oxygen increased significantly to 4.50 ppm, indicating improved aerobic conditions. EM treatment led to substantial reductions in calcium (53 %), magnesium (95 %), nitrogen (22 %), sulfate (79 %), phosphate (86 %), BOD (78 %), and COD (82 %). In contrast, dairy effluent treated without microbial consortium during the sludge activation process exhibited negligible water quality improvement.These findings underscore microbial consortium efficacy in advancing biological treatment of dairy effluent, demonstrating a significant reduction in contaminants and showcasing its potential for sustainable water reclamation. Improved alkalinity, dissolved oxygen, and nutrient content further signify positive impacts on ecosystem health. Microbial consortium emerges as a promising avenue for recycling dairy effluent, offering an economically viable and environmentally friendly solution. The study emphasizes the crucial role of microbial treatments in achieving efficient water reclamation, contributing to a cleaner and sustainable environment. Future research and broader implementation of microbial consortium in dairy industry wastewater management are recommended for enhanced environmental benefits.

Enhancing textile wastewater treatment for subsequent biological processes by integrating electrooxidation and electrocoagulation

ABSTRACT The presence of refractory contaminants in textile wastewater is one of the major concerns while handling them with the biological processes at common effluent treatment. Electro-oxidation (EO) as a standalone process is an insufficient treatment method for the abolition of inorganic contaminants (carbon and non-carbon). By incorporating electrocoagulation (EC) as an associated treatment method after EO, removal of such contaminants becomes easy, which not only makes the treated wastewater fit for biological remediation but also reduces load on biological units. The removal of non-carbonic impurities was assessed in terms of improvement in the chemical oxygen demand (COD) post EC. L25 orthogonal array of experiments was obtained using the Taguchi method. From the S/N ratio plot, the optimal process combination was obtained as, EO with current density = 25 mA/cm2, electrolysis time = 50 min followed by EC with current density = 18 mA/cm2, speed of rotation = 50 rpm and electrolysis time = 40 min. The enhancement in COD and total organic carbon removal efficiencies after EC were 65.11 and 63.57%, respectively, over EO. The biodegradability index also improved from an initial value of 0.098–0.737 post-hybrid treatment. Inorganic carbon reduced from a value of 36.37 mg/L after EO to 0.1 mg/L post EC.

Tratamiento químico de vinaza de caña de azúcar con peróxido de hidrógeno

[Introduction]: Vinasse is generated as a residue in the production of ethanol by fermentation-distillation of molasses/sugar cane juice, at a rate of 13 L/L of ethanol. It is an acid liquid, brown in color, characterized by high mineralization and Chemical Oxygen Demand (COD) values of up to 150 000 mg/L, being highly polluting. [Objective]: The objective of this research was to evaluate a vinasse treatment process with hydrogen peroxide as a source of hydroxyl radicals at laboratory scale. [Methodology]: The vinasse samples, from different distilleries in the province of Tucumán, were characterized following standardized techniques of Standard Methods. The oxidation tests were carried out with different peroxide/vinasses ratios, in a semi-batch reactor, under ambient conditions, measuring COD as an indicator parameter of the treatment. [Results]: After 5 days, an 85 % decrease in COD and an increase in the Biodegradability Index were achieved. The kinetics of the oxidative reaction was first order with respect to COD, with an apparent rate constant of 0.3694 1/day. [Conclusions]: Although the COD values allowed by local regulations (250 mg/L) were not reached, the proposed treatment is encouraging due to its simplicity, representing a potential option to the environmental challenge represented by vinaze in Latin America.

Adaptation of a microbial consortium to pelagic Sargassum modifies its taxonomic and functional profile that improves biomethane potential.

In recent years, pelagic Sargassum has invaded the Caribbean coasts, and anaerobic digestion has been proposed as a sustainable management option. However, the complex composition of these macroalgae acts as a barrier to microbial degradation, thereby limiting methane production. Microbial adaptation is a promising strategy to improve substrate utilization and stress tolerance. This study aimed to investigate the adaptation of a microbial consortium to enhance methane production from the pelagic Sargassum. Microbial adaptation was performed in a fed-batch mode for 100days by progressive feeding of Sargassum. The evolution of the microbial community was analyzed by high-throughput sequencing of 16S rRNA amplicons. Additionally, 16S rRNA data were used to predict functional profiles using the iVikodak platform. The results showed that, after adaptation, the consortium was dominated by the bacterial phyla Bacteroidota, Firmicutes, and Atribacterota, as well as methanogens of the families Methanotrichaceae and Methanoregulaceae. The abundance of predicted genes related to different metabolic functions was affected during the adaptation stage when Sargassum concentration was increased. At the end of the adaptation stage, the abundance of the predicted genes increased again. The adapted microbial consortium demonstrated a 60% increase in both biomethane potential and biodegradability index. This work offers valuable insights into the development of treatment technologies and the effective management of pelagic Sargassum in coastal regions, emphasizing the importance of microbial adaptation in this context.

Sequential electro-coagulation and electro-Fenton processes for the treatment of textile wastewater.

Textile wastewater, laden with persistent dyes and non-biodegradable organics, poses a challenge for treatment in common effluent treatment plants (CETPs) using conventional methods. Pre-treatment of textile effluents is essential to ensure compatibility with CETPs. The present study employed three-dimensional (3D) aluminum and graphite electrodes for a sequential electro-coagulation and electro-Fenton (EC + EF) process. An experimental plan of 25 experiments was constructed using Taguchi method. The combination resulted in high removal efficiencies: 99.91% for color, 93.20% for chemical oxygen demand (COD), and 91.75% for total organic carbon (TOC) for the operating parameters; for EC, current density (J): 20 mA/cm2, time (t): 45 min, speed of rotation (N): 55 rpm; and for EF, current density (J): 25 mA/cm2, time (t): 50 min, iron concentration: 40 mg/L. Post-treatment, the wastewater exhibited an enhanced biodegradability index of 0.875, rendering it suitable for CETPs. There was an increase of 11% in the total energy consumption when energy spent during rotation and aeration at the time of EC and EF, respectively, were considered. This energy increases the cost and is not accounted for, in previous research. The energy consumption in kWh per g of COD removed at optimum condition for the hybrid treatment was 0.0314, which is lower than the energy consumption by other electrochemical processes employing plate electrodes. This indicates that 3D electrodes are more energy efficient than plate electrodes. PRACTITIONER POINTS: Hybrid electrochemical processes can be used as pre-treatment method for textile effluents. Three-dimensional electrodes improve removal rates with lower energy consumption. Significant color, COD, and TOC abatement were noted post-hybrid treatment of textile wastewater. Biodegradability of the textile effluent improves after the hybrid treatment.

The scope of alum coagulation-flocculation assisted by slaked lime for the treatment of industrial wastewater containing highly concentrated Acid Black 194 dye. Optimization, molecular weight distribution and toxicity analysis

This work evaluated the capacity of the alum coagulation-flocculation (C–F) process, assisted by slaked lime, for the treatment of industrial textile wastewater (ITWW) containing highly concentrated Acid Black 194 dye. By optimizing the operating conditions ([Alum] = 16.09 g/L, [Ca(OH)2] = 5.16 g/L) through experimental design, response surface methodology, and multi-objective optimization analysis, the C–F process removed 95 % of the dye, 63 % of the COD, 60 % of the TOC, and 94 % of the total Cr concentration, with a total operating cost of 5.99 USD/m3. This improved the biodegradability index (from 0.20 to 0.26), the COS parameter (from 0.14 to 2.46), and the toxicity of the effluent (LC50 for Artemia salina increased from 15.16 mg/L to 56.7 mg/L). The calcium hardness and total hardness were also reduced by 40 % and 44 %, respectively. The C–F supernatant was composed mainly of molecules with molecular weights less than and equal to 10 kDa. An LC-MS spectral analysis revealed the presence of four residual aromatic and recalcitrant compounds in the C–F supernatant, indicating that its further treatment is required before it can be safely discharged or recycled for industrial purposes. The alum C–F process, assisted by slaked lime, demonstrated greater performance, surpassing the individual processes in effectiveness and efficiency, and confirming their synergetic effect. The alum process alone (16.09 g/L) achieved a 37 % reduction COD and 91 % color removal, at a total cost of 4.49 USD/m3. The lime process alone (5.16 g/L) achieved a 37 % COD reduction and 64 % color removal, at a total cost of 1.36 USD/m3.

Biodegradability index (BDI) as an indicator for effluents quality measurement; a case study based on different industry sectors in Matara District, Sri Lanka

ABSTRACT This study addresses the crucial need for appropriate indicators to characterize aquatic pollution, given the challenges posed by unrestricted effluent discharge globally. Focusing on wastewater from hotel and tourism industries and vehicle service stations in Matara District, Sri Lanka, we explored the relationship between biological oxygen demand (BOD) and chemical oxygen demand (COD) through the biodegradability index (BDI). Monthly water samples were collected from January 2019 to December 2022, analyzed using standard methods, and statistically evaluated. Results revealed a significant spatial variation in BDI among industry sites, with a modest temporal change. The BOD:COD ratio exhibited a slight increasing trend over time, suggesting factors beyond temporal influence. BDI correlated significantly with temperature, alkalinity, and total suspended solids (TSS), emphasizing its potential as an indicator. The study underscores the importance of complementing the BOD:COD ratio with other indicators for a comprehensive assessment of industrial effluent quality. This research contributes valuable insights into understanding wastewater characteristics, facilitating informed pollution reduction and control strategies in aquatic systems.

Effect of Inlet Pressure on the Biodegradability Index of Cavitated Herbal Waste

This paper analyzes the effect of inlet pressure on the index of biodegradability of cavitated herbal waste (HW) following its suspension in mechanically treated wastewater (MTW) for further biological processes. Hydrodynamic cavitation (HC) was carried out at inlet pressures of 3.5, 5.0, and 7.0 bar. The BOD5/COD ratio increased by 30% between the 5th and 10th minutes of the process, with the inlet pressure amounting to 3.5 bar, which indicated increased biodegradability of HW. For the higher inlet pressures used, the value of the biodegradability index (BI) increased by 23% and 13% for 5.0 and 7.0 bar, respectively, after 60 min of the process. The value of COD as well as the VS, TS, TC and TOC concentrations dropped for each analyzed inlet pressure, which indicated that complex organic compounds were effectively destroyed. The highest disintegration degree (DDCOD) was achieved with an inlet pressure of 3.5 bar. SEM analysis was performed to analyze the changing morphological structure of the HW. It was proven that the structural morphology of the herbal waste was significantly influenced by hydrodynamic cavitation, which could affect subsequent biological processing.

Chemical oxygen demand and biochemical oxygen demand analysis of discharge waters from laundry industry: monitoring, temporal variability, and biodegradability

In Europe, chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) are used as organic indicators for the analytical characterization of laundry water. However, the values of these indicators are derived from one-off analytical measurements at a defined frequency. In addition, there are few data on the temporal variability of COD and BOD5 parameters and on water biodegradability beyond 5 days. In this work, samples of physicochemical treated wastewater were collected for 1 year and their content in COD and BOD5 measured, with BOD monitored over 35 days. The results showed that, for the 24 samples studied, the average and standard deviation values were 835 ± 176 mg/L for COD and 445 ± 114 mg/L for BOD5, indicating a biodegradability index of 2.0 ± 0.4. The interpretation of the data also indicated that the concentrations were close to emission limit value, particularly for BOD5. BOD21 values were particularly high compared to the initial COD, indicating the biodegradability of water. Laundry effluents were also rich in substances very quickly biodegradable, which has been demonstrated by the values of the ratio between BOD7 and BOD5. However, a significant proportion of surfactants is not degraded, as shown by measurements of total organic carbon and anionic surfactant analysis. The results of this study could help the industrial partner involved in our project to guide its choice of the complementary method to better treat wastewater and to reduce its organic load.

Pollution Load Reduction from Domestic Wastewater with Electrocoagulation Process for Agricultural Reuse

Objectives: The present study is aimed to investigate electrocoagulation of domestic wastewater and assessment of pollutants removal efficiency for potential reuse in agriculture. Methods: The electrocoagulation treatment of domestic wastewater with Fe – Fe electrodes was performed under optimal conditions of pH (8.0), current density (0.6 mA/cm2), treatment time (45 minutes), and NaCl dose (2.8 g/L) in a slurry type of reactor. The primary clarified and biotreated domestic wastewaters were subjected to electrocoagulation with Direct Current (DC) as power source. Findings: There was observed higher pollutants removal efficiency from the biotreated wastewater as compared with the primary clarified wastewater after electrocoagulation. The treated wastewaters showed significant removal of pollutants in terms of BOD (79.5% – 87.9%), COD (86.8% – 89.5%), TDS (87.4% – 89.9%), TSS (66.7% – 75.3%), conductivity (77.8% – 78.4%), turbidity (74% – 81.2%), colour (77.7% – 86.2%), nitrates (44.1% – 51.7%), and phosphates (48.7% – 55.9%) after electrocoagulation treatment. Electrocoagulation considerably improved the biodegradability index of the primary clarified (0.59 to 0.92) and biotreated (0.69 to 0.8) wastewaters. This indicates easy removal of the pollutants further by biological processes in the aquatic ecosystems. Electrocoagulation demonstrated potential for removal of pollution from the domestic wastewater for productive reuse in agriculture and urban areas. Novelty: There exist few studies of use of electrochemical process for treatment and reuse of domestic wastewater. The treated waters complied with the regulatory standards and had satisfactory quality for reuse in agriculture and urban activities. Keywords: Electrocoagulation, Domestic wastewater, Biodegradability index, Agricultural reuse, National Green Tribunal

Simultaneous ammonia and organics degradation from municipal landfill leachate by electrochemical oxidation

ABSTRACT The two primary issues for wide implementation of the electrochemical oxidation of wastewater are the significant cost of electrode and high energy consumption. On the other side, conventional biological processes and membrane technology have several drawbacks for recalcitrant landfill leachate (LL) treatment. To address these issues, graphite/PbO2 anode was used to treat medium to mature age (biodegradability index, 5-day biochemical oxygen demand/chemical oxygen demand: 0.25) LL. To reduce the cost of the oxidation process and maximize the efficiency, operating conditions were optimized. The optimum parameter values were obtained as 24.7 mA cm−2, 180 ± 3 rpm, and 1.9 cm of current density, stirring rate, and electrode gap, respectively. Dissolved organic carbon (DOC), chemical oxygen demand (COD), and ammonia-N removal efficiencies of 55 ± 1.4%, 81 ± 1.9%, and 56 ± 3% were obtained after 8 h of degradation at optimum conditions. The decrease in aromatic substances and ultraviolet (UV) quenching materials were evaluated by UV-Visible spectroscopy and Specific UV absorbance. The conversion of aromatic compounds into simpler molecule compounds was also verified by Fourier-transform infrared spectroscopy analysis. The lab-scale anode synthesis cost was evaluated as 0.42 USD.

Assessment of Phytotoxicity in Untreated and Electrochemically Treated Leachates through the Analysis of Early Seed Growth and Inductively Coupled Plasma-Optical Emission Spectroscopy Characterization

The treatment of stabilized leachates with high refractory organic matter content, which are over 10 years old, presents a challenge. This study explored the potential of electro-coagulation (EC) and electro-oxidation (EO) treatment systems to address this issue. The objective of this study was to investigate the phytotoxicity of the proposed treatment system on seed growth and examine possible relationships between phytotoxicity results and the characterization of leachates, effluents, soil, and radicles. Phytotoxicity tests were conducted on seeds of Lactuca sativa, Cucumis sativus, and Phaseolus vulgaris, using Inductively Coupled Plasma-Optical analysis. The evolution of organic matter was monitored by fractionating the chemical oxygen demand (COD) and humic substances. The biodegradability index increased from 0.094 in raw leachate to 0.26 and 0.48 with EC and EO, respectively. Removal rates of 82%, 86%, 99%, and 81% were achieved for COD, dissolved organic carbon, color, and ammoniacal nitrogen, respectively. The biodegradable COD increased from 26% in raw leachate to 39% in the EC process and 58% in the EO process effluent. The proposed treatment system successfully broke the aromatic structures of the humic substances present in the raw leachate, thereby increasing the content of biodegradable material. Phytotoxicity tests revealed that the proposed treatment system significantly reduced the phytotoxicity of the generated effluents.

The biogas upgrading from landfill leachate pretreated with low-frequency ultrasonic: anaerobic digestion performances and energy balance

The efficient biogas production from landfill leachate (LL) is one of hot topics in anaerobic digestion systems. Higher bioavailability of LL can be achieved by application a feasible and promising pretreatment technologies in order to utilize as a substrate for anaerobic reactors. Here, the enhanced bioavailabity of LL using the low-frequency ultrasonic process and energy balance in anaerobic digestion process was estimated within incubation period of 24 days. The optimal performance of low-frequency ultrasonic for LL biodegradability index: sCOD and TVFA were estimated under influencing parameters: ultrasonic density (UD) (0.02–0.14 W/mL) and Ultrasonic time (UT) (0–12 min). Moreover, the effects of low-frequency ultrasonic pretreatment process on biogas production in batch mode anaerobic reactors operated at 37 ± 1 °C were surveyed for daily and cumulative methane production, operational performance and energy balance. An increased sCOD (820 mg/L) and TVFA (659 mg/L) were observed under optimum codition: UD (0.1 W/mL) and UT (10 min). The highest methane production (430 mL) was found in reactor 4, where %15 volume ratio of LL pretreated with low frequency ultrasonic were feed in. Energy balance assessment indicated that output energy for anaerobic reactors assissted with ultrasonic in range of + 6.99 and + 7.98 kJ/g VS removed. Therefore, incorporation the low-frequency ultrasonic and digestion process revealed a promising and economic technique to improve biomethane potential and energy balance from LL.

Treatment of fish canning wastewater by electrochemical oxidation process

The high organic load and the salinity content presented by fish canning wastewater (FCW), although a hindrance to the application of traditional treatment processes, are favourable conditions for the treatment by electrochemical oxidation (EO). In this study, the performance of EO treatment of FCW at different applied current density (j) and electrical charge, using a boron-doped diamond (BDD) anode, was evaluated regarding organic load, nitrogen, and phosphorous removals, biodegradability increment, toxicity reduction, and specific energy consumption. Experimental results showed that, for the range of the applied j studied, the efficiency of the process only depends on the applied electrical charge and that EO, with BDD anode, can effectively promote the depuration of the highly polluted FCW without requiring the addition of chemicals. After an applied charge of 60.5 kC, treated wastewater was obtained with a chemical oxygen demand of 130 mg L−1, a biodegradability index of 0.90, and a 2.8-fold reduction in toxicity towards Daphnia magna. Moreover, 80 % of nitrogen and 60 % of phosphorous removal were attained, foreseeing the potential recovery of nutrients through electrochemically mediated precipitation.

Diazinon and MCPA photo-reduction with sulfite excitation under UV irradiation and reducing agents’ generation

Diazinon (DIZ) and 4-Chloro-2-methylphenoxyacetic acid (MCPA) herbicide and widely used in agricultural lands. Present study investigates diazinon and 4-chloro-2-methylphenoxyacetic acid photo-reduction via UV/Sulfite (US) in as Advanced Reduction Processes (ARP). The ideal pH was Molar ratio of sulfite: DIZ or MCPA 1:1 and, 20 min reaction time, and pH 9, in which about 100 % reduction of DIZ and MCPA with a concentration of 10 mg L−1 was achieved and the optimal conditions were considered. Kinetic investigation increasing DIZ and MCPA concentration from 5 to 20 mgL−1, kobs increase about from 0.151 to 0.234 for DIZ and from 0.231 to 0.589 min−1. Also, reaction rate (robs) increases about from 0.755 to 4.68 for DIZ and from 1.155 to 11.78 mg L−1.min. The amount of energy consumption in DIZ solution increased from 5 to 20, respectively, from 0.73 to 2.37, and in the reduction of MCPA from 0.47 to 1.49 kWh per cubic meter. According to experiments performed in 30 min with the US process, COD levels were reduced by about 46 % of both pollutants. It is important to note that the BOD/COD ratio rose from about 0.20 to 0.48 after 30 min. Since the index of biodegradability has grown high, it can be concluded that non-biodegradable COD (NBDCOD) convert to biodegradable COD (BDCOD) and toxicity is lower than of before of treatment. This study has been very suggesting that the UV/sulfite method produces effluent with a non-toxic and ecologically beneficial manner by biological treatment or discharge directly in environment.

Techno-economic assessment of coupling ozonation and biodegradation process for the dye wastewater treatment

The biological processes have been outlined as an economical and sustainable technique for the treatment of a variety of organic pollutants. However, these processes are limited when wastewater contained recalcitrant pollutants which cause a lower biodegradability index (BOD5: COD <0.2). The present study made an effort to develop a coupled system to enhance the performance of the biological processes, and subsequently treat the low biodegradability index wastewater. The performance and feasibility of the integrated system were studied for the complete mineralization of Congo red dye from wastewater. The ozonation was carried out for 25 min with an ozone dose of 69.97 mg/L to enhance the BOD5/CODratio from 0.114 to 0.44, to make the sample suitable for biological treatment. The ozonated sample was further mineralized by biodegradation. Identification of intermediate metabolites was carried out by GC–MS analysis and the end product matches closely with fragments such as 2-Amino-1-propanol (m/z = 75) and Oxaluric acid (m/z = 132). Techno–economic assessment showed that the coupling of ozonation with biodegradation could save 34 % unitary expense in comparison to a single ozonation process.