Real Life Wastewater Research Articles

Ultrafast solid-state microwave fabrication of CoFe2O4@carbon black composite with coupling reinforcement effect towards actualizing effective water decontamination

Due to the synergistic redox coupling between the two metals, cobalt ferrite-based materials demonstrate stable degradation properties for organic pollutants by activating peroxomonosulfate (PMS). However, the challenge lies in developing the simplest and fastest methods to construct and modulate cobalt ferrite composites. In this study, CoFe2O4 nanoparticle-integrated carbon black composite catalysts (CoFe2O4-CB-x) were prepared using an environmentally friendly solid-state microwave method. The CoFe2O4-CB-120 catalyst showed excellent efficiency in degrading tetracycline (TC) through PMS activation, achieving a removal rate of nearly 90 % in 30 min with an apparent rate constant of 0.1232 min−1. The catalyst also effectively degraded various organic compounds and real-life wastewater by almost 80 %, promising application potential. Furthermore, CoFe2O4-CB-120 maintained its high activity after five cycles, attributed to its its magnetic properties facilitating good separation and preventing catalyst loss during cycling tests. The degradation mechanism of the CoFe2O4-CB-120/PMS system was thoroughly investigated, identifying key active species such as SO4•−, •OH, and 1O2, with proposed pathways for TC degradation. This study presents an innovative, simple, and efficient strategy for producing spinel cobalt ferrite and carbon composites for PMS activation in organic pollutant degradation.

Magnesium doped biochar for simultaneous adsorption of phosphate and nitrogen ions from aqueous solution

Phosphorus (P) and Ammonium Nitrogen (N) are essential nutrients for plants and environmental stability. However, their excess in water causes eutrophication, damaging aquatic ecosystems. While adsorption is a promising solution, finding affordable and efficient adsorbents remains a challenge. In this study, magnesium (Mg), iron (Fe), and Mg/Fe doped biochars (BC) adsorbents were synthesized, and evaluated for adsorption of individual P and N and a P + N mixture from a solution and wastewater from a wastewater treatment plant. Compared to other adsorbents, Mg/BC showed excellent performance in adsorbing phosphorus (P) and ammonium nitrogen (N) from aqueous solutions. It demonstrated a large adsorption capacity of 64.65 mg/g and 62.50 mg/g from individual P and N solutions, and 30.3 mg/g and 27.67 mg/g from the P and N mixture solution, respectively. In addition, Mg/BC efficiently removed P and N from real-life wastewater. In the real wastewater, P and N removal efficiencies reached 88.30% and 59.36%, respectively. Kinetics analysis revealed that the pseudo-second-order model accurately described the adsorption of phosphorus (P) and ammonium nitrogen (N) in all solutions. The adsorbent followed the monolayer-Langmuir isotherm for N ions and the multilayer-Freundlich isotherm for P, indicating efficient adsorption processes. Thermodynamic experiments indicated that the adsorption of P and N was not only feasible but also occurred spontaneously in a natural manner. This study revealed that the strategic modification of biochar plays a crucial role in advancing effective wastewater treatment technologies designed for nutrient removal.

Copper enhanced guanine electrochemical signal for nucleic acids detection in municipal tertiary wastewater

An electroanalytical method is developed for guanine detection based on its electrochemical oxidation on a clay-modified carbon paste electrode (clay-CPE). The electrochemical guanine signal is found to be significantly enhanced upon its complexation with Cu2+ ions. Cu2+-guanine complex formation is studied using UV–Vis spectroscopy and electrochemical pulse voltammetry at different ratios, with 1:2 Cu2+:guanine found to be the optimal stoichiometry. The clay modifier and the electrode are fully characterized using electron microscopy, Fourier-transform infrared, X-ray photoelectron and X-ray fluorescence spectroscopies, and X-ray diffractometry. The analytical method is fully optimized regarding the electrolyte, technique, and electrochemical parameters. A calibration curve is built obtaining a linear range of 0.1–45 µM, a limit of detection of 0.16 µM, a limit of quantification of 0.54 µM, and a sensitivity of 1.1 µA/µM, which are among the best reported so far and achieved with an environmentally friendly and low-cost method. Our system is very selective with minimal interference in the presence of interferents with concentrations as high as 100× that of guanine. The Cu2+-mediated clay-CPE-based analytical method is applied for the detection of nucleic acid in real-life wastewater, which is critical to achieving efficient wastewater treatment. This demonstrates the applicability of our method for environmental purposes and opens the door for other applications as well, such as diagnostics.

Statistical Optimization of As(V) Adsorption Parameters onto Epichlorohydrin/Fe3O4 Crosslinked Chitosan Derivative Nanocomposite using Box-Behnken Design.

In this study, Box-Behnken design (BBD) in response surface methodology (RSM) was employed to optimize As(V) removal from an aqueous solution onto synthesized crosslinked carboxymethylchitosan-epichlorohydrin/Fe3O4 nanaocomposite. The factors like solution pH, adsorbent dose, contact time and temperature were optimized by the method which shows high correlation coefficient (R2=0.9406), and a predictive quadratic polynomial model equation. The adequacy of the model and parameters were evaluated by analysis of variance (ANOVA) with their significant factors of Fischer's F - test (p<0.05). Seven significant parameters with interaction effects in the experiment with p-value < 0.0001 was observed, having a maximum removal efficiency of As(V) is 95.1%. Optimal conditions of dosage, pH, temperature, initial ion concentration and contact time in the process were found to be 0.7 g, pH 6.5, 308K, 10 mg/L and 60 min respectively. Langmuir isotherm model fitted better than the Freundlich model having a maximum adsorption capacity of 28.99 mg/g, a high regression value of 0.9988, least chi-square value of 0.1781. The process was found to follow monolayer adsorption and pseudo-second-order kinetics. Thermodynamic parameters indicate the process is spontaneous, endothermic and physisorption in nature. Successful regeneration of the adsorbent implies its applicability to the removal of arsenic from real life wastewater.

Determination of kinetic coefficients for treating synthetic oily wastewater in suspended growth batch fed reactor.

Discharge of oily wastewater imparts serious threat to the environment because of high level concentration of chemical oxygen demand (COD), biochemical oxygen demand (BOD) as well as oil and grease and it is difficult to treat such wastewater due to its inherent toxic and inhibitory property. A treatability study of oily wastewater (carrying petroleum) has been performed in the present work using a batch suspended growth reactor. The experiment was conducted using acclimatized suspended biomass in laboratory environment and the kinetic coefficients were determined which are immensely important for the design of such reactor. The oil removal efficiency was observed to be in the range of 62.84-85.45% corresponding to average MLSS concentration range of 1,797-3,668 mg/L. Haldane kinetic model was found to be the best fitted for the biodegradation of oily wastewater with acclimatised microorganisms in the present investigation. The kinetic co-efficients including Ks, Y, kd, k and ki were calculated from the experimental data and the values were compared with published results cited by various scientists. The derived kinetic coefficients values are to be useful for understanding the dynamics of substrate utilisation with production of biomass and efficient design of biological systems and also for pilot plant investigation with real life wastewater of similar nature.

Adsorptive Removal of As(V) from Aqueous Solution onto Steel Slag Recovered Iron – Chitosan Composite: Response Surface Modeling and Kinetics

In the present work iron particles was recovered by dry magnetic separation, from waste steel slag, doped with chitosan for adsorbent prepared, characterized and evaluated for the removal of As(V) from an aqueous solution. The adsorption of As(V) was optimized by using response surface methodology through Box-Behnken design model, which gave high correlation coefficient (R2 = 0.9175), and a predictive model of quadratic polynomial equation. Analysis of variance and Fischer's F-test were used to govern the parameters which interrupt the adsorption of As(V).The adsorbent was characterized by FTIR, XRD and SEM. Optimal conditions, including adsorbent dosage, pH, temperature, initial ion concentration and contact time for the removal of As(V), were found to be 0.8 g, pH 4, 308 K, 10 mg L−1 and 3 h, respectively. Langmuir isotherm model fitted better compared to the Freundlich model having a maximum adsorption capacity of 11.76 mg g−1, a high regression coefficient value of 0.993 and least chi-square value of 0.1959. The process was found to follow monolayer adsorption and pseudo-second-order kinetics. Thermodynamic parameters such as ∆S, ∆H and ∆G indicated the feasibility, spontaneous and endothermic nature of adsorption. Successful regeneration of the adsorbent implies its applicability to the removal of arsenic from real life wastewater.

Waste capacitor: A fresh approach to detect and remove Cr(VI) from water and making it an energy harvesting material

The large scale amplification of industrial discharge in the modern era is resulting in widespread water pollution, especially from various industrial effluents and wastewater containing heavy metals, posing a severe threat to our environment. In order to combat such problems, this work aims on Multifunctional Fluorescent Nano-Sensor (MFNS) mediated simultaneous detection and removal of hexavalent chromium from real life wastewater which further converts it into an energy harvesting material, namely, “Waste capacitor”. This smart material can detect the presence of the targeted heavy metal (Cr(VI)) in the wastewater and can entrap it by using a facile adsorption process. Thereafter, it will change its microstructure which further enhances its dielectric properties. Morphology, microstructure and optical properties of the synthesized material have been studied thoroughly and a turn-off based fluorescence sensing has been reported herein. Photoinduced electron transfer (PET) based fluorescence quenching is mainly responsible for this sensing mechanism. The selectivity and sensitivity of the material during fluorescence sensing have also been studied by using standard Stern-Volmer method showing that the synthesized material is tremendously selective and sensitive towards the specific target ion. High surface area with slit-like porous structure enhances the adsorption based removal of the contaminant. Nearly 76% of contaminants have been removed by using this smart material. After adsorbing specified target, this MFNS changes its microstructure and results in superior dielectric constant with a minimal tangent loss. Tremendous sensitivity (in nM range), selectivity towards the specific contaminant and adsorption of toxic heavy metal and converting it into a green energy harvesting material (waste capacitor) makes this smart multifunctional material a real waste to wealth converter.

Isolation of Chromium Resistant Bacteria from Contaminated Soil and Its Performance Evaluation for Hexavalent Chromium Removal

The present study deals with the metal tolerance as well as metal resistance characteristic in bacteria isolated from mostly tannery effluent contaminated soil. Seven chromium resistant bacteria (CrRB 1-7) were isolated for this study in LB medium amended with 100 mg/L filter sterilized hexavalent chromium (Cr(VI)) solution. The minimum inhibitory concentrations (MIC) of these gram positive and gram negative bacteria were found in the range of 350 – 450 mg/L of Cr(VI) concentration. Cr(VI) removal potential of these seven isolates were also studied. One isolate CrRB 1 possessed the ability to remove 98.4% Cr(VI) within 24h in LB medium. The effect of hexavalent chromium on their biomass growth potential were further observed. For CrRB1 least differences were found in doubling time calculated from growth curve in presence and absence of Cr(VI). CrRB 1 was then further studied in real life wastewater i.e. tannery effluent to evaluate its performance for removal of Cr(VI).The favorable outcomes encourages for the use of this isolate in green bioremediation technology for tannery industry. The subsequent reactor studies requires to reveal its performance for in-situ application.

Gd(III)-Doped Boehmite Nanoparticle: An Emergent Material for the Fluorescent Sensing of Cr(VI) in Wastewater and Live Cells.

This article reports the effect of Gd(III) doping on the structure, microstructure, and optical properties of boehmite nanoparticles. The bright-blue fluorescence along with a long lifetime makes our material an efficient candidate for optical applications. Our material particularly targets and eliminates hexavalent chromium ions (Cr(VI)) from aqueous media, which turns it into a multifunctional fluorescent nanosensor (MFNS). The development of an efficient hexavalent chromium ion (Cr(VI)) sensor to detect and quantify Cr(VI) ions is still a serious issue worldwide. Thus, this work will be very beneficial for various environmental applications. No such work has been reported so far which includes cost-effective and biocompatible boehmite nanoparticles in this field. Detailed synthesis and characterization procedures for the MFNS have been incorporated here. The biocompatibility of the MFNS has also been studied rigorously by performing cell survivability assay (MTT) and cellular morphology assessments. Our extensive research confirmed that the "turn-off" sensing mechanism of this sensor material is based on a collisional quenching model which initiates the photoinduced electron transfer (PET) process. High selectivity and sensitivity (∼1.05 × 10-5 M) of the MFNS toward hexavalent chromium ions even in real life wastewater samples have been confirmed, which makes this fluorescent probe a potential candidate for new age imaging and sensing technologies.

Defining the kinetics of the novel application of anaerobic acetogenics for treating textile dyeing wastewater

A bench-scale completely mixed reactor was operated under anaerobic acetogenic conditions to treat real life wastewater from a textile processing and dyeing facilities. The reactor performance data was modeled with respect to removal of soluble chemical oxygen demand (SCOD) and color to critical elements that needs to be neutralized before discharge to the environment. The reactor performance is defined by a first order model for both SCOD and color transformation. Transformation of SCOD increase with length of reactor operation indicating that culture acclimation plays a significant role in the performance of the reactor (day 2: k = 0.16 day− 1, day 7 k = 2.17 day− 1; an increase of roughly 13 folds). Upon optimum operation first order rate constant “k” for the degradation of the textile dyeing wastewater was 0.047 h− 1 (95% confidence bound; 0.030, 0.064, r2 = 0.84, RMSE = 10.5). Culture acclimation facilitates extent of SCOD removal (day 2: 39.7%, day 7: 89.7%). Food to microorganism ratio affects both the kinetic parameter “k” and extent of SCOD transformation with an optimum F/M ratio of 0.1. The importance of culture acclimation was evident in color removal as well, between day 5 to day 9 of operation. The kinetic constant “k” increased by 10.2 folds (k = 0.094 day− 1 to k = 0.96 day− 1). The extent of color removal also increased by a factor of 2.9 (day 5: 27.4%, day 9: 79.2%) with acclimation. The experimental and modeling program validates that anaerobic acetogenic process can be successfully applied to treat textile processing dyeing wastewater.

Field Scale Evaluation of Seasonal Wastewater Treatment Efficiencies of Free Surface-Constructed Wetlands in ICRISAT, India

The disparity between volume of wastewater generated and treated has resulted in severe water pollution and eutrophication of the water bodies in most Indian cities. Constructed wetlands (CWs) present a low-cost wastewater treatment option; however, field scale studies with real life wastewater are limited. Eichhornia crassipes (water hyacinth), Typha latifolia (Typha) and Pistia stratiotes (water lettuce) grow abundantly in eutrophicated water bodies, and are known for their nutrient uptake ability. In the present study, the wastewater of a nearby urban residential colony was treated by two-field scale free water surface CWs operating under identical hydraulic loading. The first treatment cells, in each of these two CWs were vegetated with Typha. The second treatment cells were vegetated with water hyacinth (CW-1) in one of the CWs and with water lettuce (CW-2) in the other. Wastewater treatment efficiencies of these free water surface CWs were evaluated, in terms of the removal efficiencies for key parameters, viz. chemical oxygen demand (COD), ammoniacal and nitrate nitrogen, phosphate, sulphate and total suspended solids (TSS). The CW-1 showed greater seasonal variation in performance. A steady removal efficiency of 35–40% was observed for ammoniacal nitrogen in both the free water surface CWs throughout the year, though removal efficiency of nitrate nitrogen reduced significantly during the winter. Plant sample analysis showed that the N, P and K uptake capacities of water lettuce were 1.53, 1.55 and 1.34 times higher than that of water hyacinth, for identical wastewater loading. The dry weight of the harvested biomass for water lettuce, during summer months, was much higher at 5.63 g/m2/d compared to 3.8 g/m2/d for water hyacinth.

Lessons learnt from the application of a multi-variable controller for nitrogen removal in the Mekolalde wastewater treatment plant: good simulation practices in control

Although often perceived as tools for use by scientists, mathematical modelling and simulation become indispensable when control engineers have to design controllers for real-life wastewater treatment plants (WWTPs). Nonetheless, the design of effective controllers in the wastewater domain using simulations requires effects, such as the nonlinearity of actuators, the time response of sensors, plant model uncertainties, etc. to have been reproduced beforehand. Otherwise, control solutions verified by simulation can completely underperform under real conditions. This study demonstrates that, when all the above effects are included at the outset, a systematic use of simulations guarantees high quality controllers in a relatively short period of time. The above is exemplified through the Mekolalde WWTP, where a comprehensive simulation study was conducted in order to develop a control product for nitrogen removal. Since its activation in May 2011, the designed controller has been permanently working in the plant which, from this time onwards, has experienced significant improvements in the quality of water discharges combined with a lower utilization of electricity for wastewater treatment.

Biodegradation kinetics of Bi-substrate solution of phenol and resorcinol in an aerobic batch reactor

Phenol and resorcinol compounds are found to co-exist in real-life wastewater, especially in petrochemical, coking and coke-oven wastewater. An indigenous mixed microbial culture isolated from effluent treatment plant of a coke oven industry has been employed to investigate for its biodegradation capacity of bi-solute mixture of phenol and resorcinol under aerobic batch reactor operation. A 22 full factorial design with the two substrates at two different levels of initial concentration ranges (high and low) was explored to design the biodegradation experiments. The effect of individual substrate concentrations and their interaction on rate of phenolics biodegradation were also determined. The phenol and resorcinol as substrates were completely utilized after 22 hrs when the solutes are present at low concentrations of 100 mg/L each. But the culture has taken total 58 hrs to biodegrade completely higher initial concentrations i.e., 400 mg/L of each substrate. This study also observed that both specific growth rate of the culture and the specific substrate degradation rate have descended to lower value in presence of phenol and resorcinol as dual substrate in the solution compared to their presence as single substrate, showing the interaction and inhibition by each substrate. Sum kinetic model was used to describe the variation in the specific substrate degradation rates by the mixed culture. From the interaction parameters obtained from this model, it has been observed that resorcinol inhibits specific substrate degradation rate to a higher extent than inhibition caused by phenol (IResorcinol, Phenol = 0.5, IPhenol, Resorcinol = 0.1, RMSE = 0.04361)

Optimal Design of Regional Wastewater Pipelines and Treatment Plant Systems

This manuscript describes the application of a genetic algorithm model for the optimal design of regional wastewater systems comprised of transmission gravitational and pumping sewer pipelines, decentralized treatment plants, and end users of reclaimed wastewater. The algorithm seeks the diameter size of the designed pipelines and their flow distribution simultaneously, the number of treatment plants and their size and location, the pump power, and the required excavation work. The model capabilities are demonstrated through a simplified example application using base runs and sensitivity analyses. Scaling of the proposed methodology to real life wastewater collection and treatment plants design problems needs further testing and developments. The model is coded in MATLAB using the GATOOL toolbox and is available from the authors.

Effect of solids retention time and wastewater characteristics on biological phosphorus removal

The paper deals with the effect of wastewater, plant design and operation in relation to biological nitrogen and phosphorus removal and the possibilities to model the processes. Two Bio-P pilot plants were operated for 2.5 years in parallel receiving identical wastewater. The plants had SRT of 4 and 21 days, the latter had nitrification and denitrification. The plant with 4 days SRT had much more variable biomass characteristics, than the one with the high SRT. The internal storage compounds, PHA, were affected significantly by the concentration of fatty acids or other easily degradable organics in the wastewater, and less by the plant lay-out. The phosphorus removal is mainly dependent on availability in the wastewater of fatty acids but also by the suspended solids in the effluent, which is higher in the plant with nitrification-denitrification, probably due to a higher SVI or denitrification in the settler. The addition of glucose to the influent seems to have an effect on the performance of the plants similar to that of acetic acid. In spite of great load variations over time to the pilot plants and the different operational modes, the study of population dynamics showed less significant variations with time which has importance in relation to modelling. The overall conclusion of the comparison between the two plants is that the biological phosphorus removal efficiency under practical operating conditions is affected by the SRT in the plant and the wastewater composition. Thus great care should be taken when extrapolating results from one type of plant to another. Indirectly the experiments confirm that results from lab-experiments with artificial wastewater are difficult to extrapolate through modelling to real life wastewater and conditions. The 2.5 years time series can be valuable in verification of models for Nitrogen and Enhanced Biological Phosphorus Removal.

Wastewater nitrification kinetics using reciprocating jet bioreactor

Kinetic investigations on growth parameters of nitrifying and COD oxidizing bacteria were carried out with recourse to a three stage reciprocating jet bioreactor system using real life wastewater. The system employed in this investigation essentially consisted of separate aerobic oxidation stage along with nitrification stage and anaerobic denitrification stage with facility for biomass recirculation whenever necessary. Steady-state COD oxidation reactor performance was assessed for various values of residence time. Yield coefficient and decay coefficient of COD oxidizing biomass were obtained as 0.3329 kg BM/kg COD and 0.0032 (1/h) respectively.

Pumped Wastewater Collection Systems Optimization

Identifying the need for intermediate and/or end pumping in real life wastewater collection systems, an optimization algorithm is developed for the design of gravity‐cum‐pumped systems with recourse to dynamic programming. The problem of dimensionality is minimized through cost effective feasible groupings at junction manholes and with division of algorithm in two parts. The first part identifies optimal control variables associated with each link and stores the same while the second part uses these stored values along with input data to prepare detailed hydraulic and cost statements. The effectiveness of the algorithm is tested through two case studies.