Treatment of the baker's yeast wastewater by electrocoagulation

The performance of pharmaceutical wastewater treatment system of electrocoagulation assisted adsorption using perforated electrodes to reduce passivation

The integrated electrocoagulation-assisted adsorption (ECA) system with a solar photovoltaic power supply has gained more attention as an effective approach for reduction chemical oxygen demand (COD) from pharmaceutical wastewater (PhWW). In this research, the ECA system was used for the treatment of PhWW. Several operating parameters were investigated, including electrode number, configuration, distance, operating time, current density, adsorption time, and temperature. A current density of 6.656 mA/cm2, six electrodes, a 20-min time, a 4 cm distance, an MP-P configuration, and a 45 °C temperature produced the maximum COD reductions, where the operating cost of conventional energy was 0.273 $/m3. The EC, adsorption, and combination of EC and adsorption processes achieved efficient COD reductions of 85.4, 69.1, and 95.5%, respectively. The pseudo-second-order kinetic model and the Freundlich isotherm fit the data of the endothermic adsorption process. Therefore, it was found that the combination processes were superior to the use of these processes in isolation to remove COD.

Electrochemical treatment of textile wastewater using copper electrodes

The conventional electrode aluminum used in electrocoagulation (EC) for the textile wastewater undergoes pitting type of corrosion, so dissolution of the same is very high during electrolysis. This research focuses on the treatment of real-time textile effluent with copper electrodes that corrode uniformly during electrolysis, with optimizing operating parameters for high color removal efficiency (CRE%). The sludge acquired was analyzed by XPS and XRD to study the mechanism of dye removal. The treated effluent was subjected to phytotoxicity analysis using Vigna radiata to study the toxicity effect of the intermediary products. 98.6% of CRE was attained in treating the effluent with copper electrodes. XPS and XRD results showed that both Cu(OH)2 and CuO served as coagulants in the dye removal. The phytotoxicity results showed that the percentage of germination, shoot and root lengths of Vigna radiata in the treated effluent were similar to the results obtained for the control.

Treatment technologies for bakers' yeast production wastewater

Researchers in recent years have utilized a broad spectrum of treatment technologies in treating bakers' yeast production wastewater. This paper aims to review the treatment technologies for the wastewater, compare the process technologies, discuss recent innovations, and propose future perspectives in the research area. The review observed that nanofiltration was the most effective membrane process for the treatment of the effluent (at >95% pollutant rejection). Other separation processes like adsorption and distillation had technical challenges of desorption, a poor fit for high pollutant load and cost limitations. Chemical treatment processes have varying levels of success but they are expensive and produce toxic sludge. Sludge production would be a hurdle when product recovery and reuse are targeted. It is difficult to make an outright choice of the best process for treating the effluent because each has its merits and demerits and an appropriate choice can be made when all factors are duly considered. The process intensification of the industrial-scale production of the bakers' yeast process will be a very direct approach, where the process optimisation, zero effluent discharge, and enhanced recovery of value-added product from the waste streams are important approaches that need to be taken into account.

Integrated process for protein, pigments, and biogas production from baker's yeast wastewater using filamentous fungi

Baker's yeast production industry generates large quantities of high chemical oxygen demand (COD) wastewater. The integration of baker's yeast wastewater (BYW) for an innovative two-step waste biorefinery process by producing protein-rich fungal biomass and biogas along with COD and nutrients removal was the main object of the present research. In the first step, fungal biomass production from BYW was investigated using four species of filamentous fungi. The maximum biomass yield of 5.13 g/L BYW containing 43.8% mycoprotein and 36.3% COD removal was achieved by A. oryzae. In the second step, to produce biogas and further remove organic matter, the effluent of fungal fermentation was subjected to anaerobic digestion and COD removal between 22.4 and 44.2% was obtained. Overall, 1 m³ of BYW yielded 5.13 kg of protein-rich biomass and 1.42 m³ of methane. Additionally, pigment production using N. intermedia was investigated, and 1.54 mg carotenoids/g biomass was produced.

Use of Electrocoagulation for Treatment of Pharmaceutical Compounds in Water/Wastewater: A Review Exploring Opportunities and Challenges

Increasing dependency on pharmaceutical compounds including antibiotics, analgesics, antidepressants, and other drugs has threatened the environment as well as human health. Their occurrence, transformation, and fate in the environment are causing significant concerns. Several existing treatment technologies are there with their pros and cons for the treatment of pharmaceutical wastewater (PWW). Still, electrocoagulation is considered as the modern and decisive technology for treatment. In the EC process, utilizing electricity (AC/DC) and electrodes, contaminants become coagulated with the metal hydroxide and are separated by co-precipitation. The main mechanism is charge neutralization and adsorption of contaminants on the generated flocs. The range of parameters affects the EC process and is directly related to the removal efficiency and its overall operational cost. This process only could be scaled up on the industrial level if process parameters become optimized and energy consumption is reduced. Unfortunately, the removal mechanism of particular pharmaceuticals and complex physiochemical phenomena involved in this process are not fully understood. For this reason, further research and reviews are required to fill the knowledge gap. This review discusses the use of EC for removing pharmaceuticals and focuses on removal mechanism and process parameters, the cost assessment, and the challenges involved in mitigation.

Comparison of poly ferric chloride and poly titanium tetrachloride in coagulation and flocculation process for paper and cardboard wastewater treatment

The current study investigated the efficiency of poly ferric chloride (PFC) and poly titanium tetrachloride (PTC) in coagulation-flocculation process for treatment of paper and cardboard wastewater. The effect of pH (5-11), coagulant concentrations (100-1000 mg/L), mixing rate (10-60 rpm), mixing time (5-25 min), and settling time (5-30 min) were examined. The results showed that the removal efficiency for turbidity, total suspended solids (TSS), and chemical oxygen demand (COD) by PFC and PTC coagulants increased with pH rising up to 9 for the former and 7 for the latter coagulant. Furthermore, the removal efficiency for the afore-mentioned parameters increased along with a 30 rpm increase in the mixing rate, while the mixing time reached 20 min. It was also found that the best removal efficiencies for turbidity, TSS, and COD by PFC under optimal conditions (pH 9, coagulant dose 800 mg/L, and settling time of 25 min) were 97.11%, 99.1%, and 84.91%, respectively. In addition, the removal efficiencies for PTC (optimal conditions of pH 7, coagulant dose 600 mg/L, and settling time of 15 min) were found to be 98.29%, 99.29%, and 86.42%, respectively. Water recovery and the produced sludge volume by PFC were 80% and 200 cm³, respectively, in the settling time of 25 min and for PTC were 81.5% and 185 cm³, respectively, in the settling time of 15 min. Costs of the coagulation-flocculation process for treatment 1 m³ of paper and cardboard wastewater using PTC and PFC were 0.42 $ and 0.32 $, respectively. Finally, it can be concluded that compared to PFC, PTC with higher settling rate has a greater efficiency for treatment of paper and cardboard wastewater.

Review on current approach for treatment of palm oil mill effluent: Integrated system

Malaysia is one of the countries that is well known for its palm oil based products and exports all over the world. Over the years, palm oil mill has been rising at alarming rate in Malaysia, causing palm oil-based wastes to increase especially palm oil mill effluent (POME). POME in Malaysia are channelled into water bodies such as rivers after treated mostly with conventional biological method. However, with current technologies and knowledge, conventional POME treatments are seen to be outdated and require major improvements as greenhouse gaseous are emitted to the environment as well as being less cost effective. Integrated systems that combine two or more conventional methods are introduced and reviewed to provide insights on the advantages and disadvantages of the system if it is to be implemented in real life plant. Integrated systems that focus on combining conventional methods are compiled and reviewed specifically for POME treatment. Among the integrated methods that are reviewed includes biological with membrane, adsorption with magnetic field exposure, adsorption with membrane and electrocoagulation with membrane. The systems are seen to give excellent color, chemical oxygen demand (COD) and total suspended solids (TSS) removal with average of higher than 90%. Reduction in space utilization, improved treatment time as well as simplified operating system were reported when integrated systems are applied as compared to conventional treatment of POME.

Long term performance of a pilot scale anaerobic membrane bioreactor treating beet molasses based industrial wastewater

Baker's yeast industries (BYI) generate highly polluted effluents, especially vinasse from yeast separators, with very high chemical oxygen demand (COD), nitrogen, sulphate and salts, mainly potassium and calcium. Anaerobic treatment is the most commonly applied method for treating BYI wastewaters. However, it is quite challenging to obtain a high performance due to the difficulties in biomass retention. Moreover, it does not provide compliance with COD and color discharge limits when used as a sole treatment process. In this context, a pilot scale anaerobic membrane bioreactor, which provides excellent biomass retention, was operated to investigate its treatment performance for vinasse from a BYI. The reactor achieved a COD removal between 48% and 92% up to a volumetric load of 10 kg COD m³ d^-1. A specific methane production of 0.37 m³ CH₄ kg^-1 COD_removed was observed in the study. On the other hand, passage of inert organic compounds through membrane deteriorated permeate quality and treatment efficiency. High alkalinity and pH led to the accumulation of calcium precipitates, which reduced volatile solids fraction of sludge and biomass activity in the reactor. The present study showed the operational challenges and potential drawbacks of AnMBR systems for BYI wastewater treatment. The experience gained in the pilot system can be utilized in the design and operation of full scale AnMBRs for high strength industrial effluents.

A comprehensive review on contaminants removal from pharmaceutical wastewater by electrocoagulation process

The pharmaceuticals are emergent contaminants, which can create potential threats for human health and the environment. All the pharmaceutical contaminants are becoming enormous in the environment as conventional wastewater treatment cannot be effectively implemented due to toxic and intractable action of pharmaceuticals. For this reason, the existence of pharmaceutical contaminants has brought great awareness, causing significant concern on their transformation, occurrence, risk, and fate in the environments. Electrocoagulation (EC) treatment process is effectively applied for the removal of contaminants, radionuclides, pesticides, and also harmful microorganisms. During the EC process, an electric current is employed directly, and both electrodes are dissoluted partially in the reactor under the special conditions. This electrode dissolution produces the increased concentration of cation, which is finally precipitated as hydroxides and oxides. Different anode materials usage like aluminum, stainless steel, iron, etc. are found more effective in EC operation for efficient removal of pharmaceutical contaminants. Due to the simple procedure and less costly material, EC method is extensively recognized for pharmaceutical wastewater treatment over further conventional treatment methods. The EC process has more usefulness to destabilize the pharmaceutical contaminants with the neutralization of charge and after that coagulating those contaminants to produce flocs. Thus, the review places particular emphasis on the application of EC process to remove pharmaceutical contaminants. First, the operational parameters influencing EC efficiency with the electroanalysis techniques are described. Second, in this review emerging challenges, current developments and techno-economic concerns of EC are highlighted. Finally, future recommendations and prospective on EC are envisioned.

A novel electrocoagulation electrode configuration for the removal of total organic carbon from primary treated municipal wastewater

In this paper, the removal of total organic carbon (TOC) from a primary treated municipal wastewater using a new electrode configuration in electrocoagulation was evaluated. The used electrode configuration induces a dielectrophoretic (DEP) force by using an asymmetrical aluminum electrode with an alternating current power supply. The impact of applied current, electrolysis time, and interelectrode distance on the removal efficiency of TOC were evaluated. The experimental results showed that the maximum removal efficiency of TOC was obtained at 30 min electrolysis time, 600 mA applied current, and 0.5 cm interelectrode distance. Under these operating conditions, the TOC removal was 87.7% compared to 80.5% using symmetrical aluminum electrodes with no DEP effect. The energy consumption at the selected operating conditions was 3.92 kWh/m³. The experimental results were comparable with the simulation results done by COMSOL Multiphysics software.

Removal of platinum (IV) from aqueous solutions with yeast-functionalised bentonite

There is a need for cheap but, efficient methods for the removal of precious metals from wastewaters, which are normally lost during mineral processing. Moreover, the disposal of yeast waste from brewing has been a problem in many parts of the world. In this study, the removal of Pt(IV) from aqueous solutions using the readily available bentonite clay functionalised with spent yeast from brewing was investigated. The maximum adsorption capacity of Pt(IV) with 100 mg yeast-functionalised bentonite at pH 2 within 90 min was 255 μg g^-1 (98.5% efficiency) but, decreased as pH increased. The adsorption capacity of Pt(IV) was insignificantly (p > 0.05) affected by the presence of competing ions (Fe(III), Ca(II), Mg(II), K(I), Co(II)^, Ni(II), Hf(IV), Zn(II) and other platinum group metals (PGMs)). Moreover, most of these metals were significantly adsorbed along with Pt(IV). The indicative cost-benefit analysis showed that 1 kg of the yeast-functionalised bentonite can remove ∼700 g Pt(IV) in which a profit of more than USD20000 can be made. The bentonite functionalised with spent yeast from brewing has a potential to recover lost PGMs in wastewater. Since, this is a cheap process, the mining and other industries can make much profit from such recoveries.

Analysis of the Potential of an Increase in Yeast Output Resulting from the Application of Additional Process Wastewater in the Evaporator Station

This paper reports the results of an analysis of process wastewater streams in the context of an increase in yeast production. This research is based on the analysis of data from the biggest yeast factory in Europe. The research presented in this paper involves the analysis of the influence of direction of additional wastewater into the evaporator station on yeast production. In the process wastewater, nitrogen is mainly present in organic forms. The analysis reported in this paper involves the concentration of total nitrogen in wastewater streams, as it is the main parameter applied to determine the amount of wastewater that can be applied in agricultural fields. Directing additional wastewater into the evaporator station can offer a simultaneous increase in the volume of its use in the field of agriculture and will ultimately yield an increase in productivity (under conditions where additional pressure on the natural environment is not exerted). The results obtained in this analysis were an increase in production of ηYp = 0.1027, corresponding to about 6500 Mg of yeast per year. This is a feasible value, which can be derived from the existing agricultural field area and the properties of the evaporator station in the factory. At the same time, the same increase in the volume of organic fertilizer is obtained. This fertilizer is generated as a byproduct of the pre-treatment of wastewater at the evaporator station. Thus, the increase in the production of the fertilizer can have a positive effect on fields in local farms, which are typically the recipients of this fertilizer.

Optimized synthesis of carbon-doped nano-MgO and its performance study in catalyzed ozonation of humic acid in aqueous solutions: Modeling based on response surface methodology

This research study focused on the optimization of the synthesis of carbon-doped nano-MgO (C-MgO) and the investigation of its catalytic capacity in a catalytic ozonation process (COP) for the removal of humic acid (HA). Characterization analyses, including SEM, EDX, XRD, BET, and photoluminescence test showed that the C-MgO was successfully synthesized. L8 orthogonal arrays according to the Taguchi methodology optimized the synthesis of the C-MgO as follows: sucrose to MgO ratio = 0.5, sonication time = 15 min, calcination temperature = 400 °C and pH = 10.5. A central composite design based on response surface methodology was employed to optimize and model the COP in the removal of HA. A quadratic polynomial model with p-value < 0.0001 and R² = 0.9988 showed a better fit to experimental responses. The optimum levels of the studied parameters in the COP based on the predictive model were obtained as follows: pH = 9.5, reaction time = 12 min, catalyst dose = 1 g/L, and HA concentration = 5 mg/L. The HA mineralization was determined to be 86.8% at the 100 min reaction time. Additionally, the COP exhibited 34% synergistic effect and the kinetic rate constant of 0.1898 min^-1 in the HA removal. The presence of tert-butanol, methanol, salicylic acid, and some anions did not significantly affect the removal of the HA in the COP. From a practical view, this report indicated that the C-MgO catalyst could be potentially applied in the COP for the treatment of the water having high concentrations of HA substances.

Applicability of the electrocoagulation process in treating real municipal wastewater containing pharmaceutical active compounds

In this study, the viability of using electrocoagulation process as a method for pharmaceuticals removal from real municipal wastewater was demonstrated. Batch experimental runs were performed using a simple laboratory scale electrochemical reactor with aluminium and stainless steel as anode and cathode, respectively. Diclofenac (DCF), carbamazepine (CBZ) and amoxicillin (AMX) were selected as representative of pharmaceuticals frequently detected in the aquatic environment. The effects of varying experimental parameters namely current density (0.3, 0.5 1.15 and 1.8 mA cm^-2), initial pharmaceutical concentration (0.01, 4 and 10 mg L^-1), electrolysis duration (3, 6 and 19 h) and application mode (continuous vs. intermittent) on pharmaceutical removal efficiencies were evaluated. High pharmaceutical abatement was recorded at elevated current density and prolonged electrolysis duration due to additional electro-generated coagulant species in solution.

Synergy of flocculation and flotation for microalgae harvesting using aluminium electrolysis

Microalgae are often used as feedstock for renewable biofuel production and as pollutant up-takers for wastewater treatment; however, biomass harvesting still remains a challenge in field applications. In this study, electro-flocculation using aluminium electrolysis was tested as a method to collect Chlorella vulgaris. The electrolysis products were positively charged over a wide pH range below 9.5, which gave them a flocculation potential for negatively charged microalgae. As flocculants were in-situ generated and gradually released, microalgae flocs formed in a snowballing mode, resulting in the compaction of large flocs. When higher current density was applied, microalgae could be harvested more rapidly, although there was a trade-off between a higher energy use and more residual aluminium in the culture medium. Benefits of this flocculation method are twofold: the phosphate decrease in post-harvesting could improve nutrient removal in microalgae based wastewater treatment, while the ammonium increase may favor microalgae recovery for medium recycling.

Electrocoagulation process to Chemical and Biological Oxygen Demand treatment from carwash grey water in Ahvaz megacity, Iran

In this work, we present the result of an electric coagulation process with iron and aluminum electrodes for removal of chemical and biological oxygen demand (COD and BOD) from grey water in different car washes of Ahvaz, Iran. Nowadays, one of the important dangerous that can contaminate water resources for drinking, agriculture and industrial is Car wash effluent [1,2]. In this study, initial COD and BOD concentration, pH of the solution, voltage power and reaction time was investigated. The concentration level of remaining COD and BOD in samples was measured, using DR/5000 UV–vis HACH spectrophotometer [3,4]. The effects of contact time, initial pH, electrical potential and voltage data on removal of COD and BOD were presented. Statistical analysis of the data was carried out using Special Package for Social Sciences (SPSS 16).

A review of electrocoagulation technology for the treatment of textile wastewater

The conventional coagulation technique of textile wastewater treatments is plagued with the issue of low removal rate of pollutants and generation of a large quantity of sludge. Recently, electrocoagulation (EC) technique gained immense attention due to its efficiency. The technique involves dissolution of the sacrificial anodes to provide an active metal hydroxide as a strong coagulant that destabilizes and amasses particles and then removes them by precipitation or adsorption. EC process is influenced by operating parameters such as applied current density, electrodes material and configuration, type of electrical connection, pH and conductivity of the solution, and mixing state. Consequently, this work reviewed the major and minor reactions of EC process with operational parameters, design of EC cell, mass transfer studies and modeling, and industrial wastewater applications. The work also includes comparison of EC technique with conventional coagulation and combinations with other techniques. Special emphasis is on removal of pollutants from textile wastewater. Further, the electrical energy supplies and cost analysis are also discussed. Even though several publications have covered EC process recently, no review work has treated the systematic process design and how to minimize the effect of passivation layer deposited on the surface of the electrodes. EC process with rotating electrodes has been recommended to reduce this phenomenon. The effect of electrodes geometry is considered to enhance the conductivity of the cell and reduce energy consumption. The studies of ionic mass transfer were not implemented before special by limiting current method during the EC process. Moreover, no aforementioned studies used computational fluid dynamics modeling to present the mass transfer inside the EC reactor.

A comprehensive review of electrocoagulation for water treatment: Potentials and challenges

Electrocoagulation is an effective electrochemical approach for the treatment of different types of contaminated water and has received considerable attention in recent years due its high efficiency in dealing with numerous stubborn pollutants. It has been successful in dealing with organic and inorganic contaminants with negligible or almost no generation of by-product wastes. During the past decade, vast amount of research has been devoted to utilizing electrocoagulation for the treatment of several types of wastewater, ranging from polluted groundwater to highly contaminated refinery wastewater. This paper offers a comprehensive review of recent literature that has been dedicated to utilizing electrocoagulation for water treatment, focusing on current successes on specific applications in water and wastewater treatment, as well as potentials for future applications. The paper examines such aspects as theory, potential applications, current challenges, recent developments as well as economical concerns associated with the technology. Most of the recent EC research has been focusing on pollutant-specific evaluation without paying attention to cell design, process modeling or industrial applications. This review attempts to highlight the main achievements in the area and outlines the major shortcomings with recommendations for promising research options that can enhance the technology and broaden its range of applications.

Analysis of sludge aggregates produced during electrocoagulation of model wastewater

This paper presents the results of the study of sludge aggregates produced during electrocoagulation of model wastewater of a composition corresponding to the effluents from the cellulose and paper industry. Wastewater was electrocoagulated statically using aluminium electrodes with a current density of 31.25 A m(-2) and 62.50 A m(-2). In subsequent stages of the treatment, sludge flocs were collected, their size was studied and their floc settling velocity (30-520 μm s(-1)) and fractal dimension (D) were determined. The values of D ranged from 1.53 to 1.95 and were directly proportional to the degree of wastewater treatment. Higher values of D were determined for sludge with lower water content (after 24 hours' settling). Fractal dimension can therefore be used as an additional parameter of wastewater treatment control.

Post-treatment of molasses wastewater by electrocoagulation and process optimization through response surface analysis

Molasses wastewater is a high strength effluent of food industry such as distilleries, sugar and yeast production plants etc. It is characterized by a dark brown color and exhibits a high content in substances of recalcitrant nature such as melanoidins. In this study, electrocoagulation (EC) was studied as a post treatment step for biologically treated molasses wastewater with high nitrogen content obtained from a baker's yeast industry. Iron and copper electrodes were used in various forms; the influence and interaction of current density, molasses wastewater dilution, and reaction time, on COD, color, ammonium and nitrate removal rates and operating cost were studied and optimized through Box Behnken's response surface analysis. Reaction time varied from 0.5 to 4 h, current density varied from 5 to 40 mA/cm(2) and dilution from 0 to 90% (v/v expressed as water concentration). pH, conductivity and temperature measurements were also carried out during each experiment. From preliminary experiments, it was concluded that the application of aeration and sample dilution, considerably influenced the kinetics of the process. The obtained results showed that COD removal varied between 10 and 54%, corresponding to an operation cost ranging from 0.2 to 33 euro/kg COD removed. Significant removal rates were obtained for nitrogen as nitrate and ammonium (i.e. 70% ammonium removal). A linear relation of COD and ammonium to the design parameters was observed, while operation cost and nitrate removal responded in a curvilinear function. A low ratio of electrode surface to treated volume was used, associated to a low investment cost; in addition, iron wastes could be utilized as low cost electrodes i.e. iron fillings from lathes, aiming to a low operation cost due to electrodes replacement. In general, electrocoagulation proved to be an effective and low cost process for biologically treated molasses-wastewater treatment for additional removal of COD and nitrogen content and color reduction. Treated effluent samples with good quality were produced by EC, with COD, NH4-N and NO3-N concentrations of 180, 52 and 2 mg/l respectively. Response surface analysis revealed that optimized conditions could be established under moderate molasses wastewater dilution, (e.g. 45%), at 3.5 h treatment time and 33 mA/cm(2) current density.

Effect of bipolar electrode material on the reclamation of urban wastewater by an integrated electrodisinfection/electrocoagulation process

This work presents an integrated electrodisinfection/electrocoagulation (ED-EC) process for urban wastewater reuse that employs iron bipolar electrodes. Boron doped diamond (BDD) was used as the anode and stainless steel (SS) as the cathode. A perforated iron plate was introduced between the anode and cathode to function as a bipolar electrode. This ED-EC combined cell makes it possible to conduct the simultaneous removal of microbiological content and elimination of turbidity from urban wastewater. The results show that current densities greater than or equal to 6.70 A m(-2) enable complete disinfection of the effluent and the removal of more than 90% of its initial turbidity. Hypochlorite and chloramines formed during the ED-EC process were found to be the main compounds responsible for the disinfection process. Furthermore, a cell configuration of cathode (inlet)-anode (outlet) improves the process performance by enhancing turbidity removal. Finally, the influence of the bipolar electrode material (iron or aluminium) was assessed. The results indicate that the efficiency of the electrodisinfection process depends mainly on the anodic material and is not influenced by the material of the bipolar electrode. In contrast, the removal of turbidity is more efficient when using iron as a bipolar electrode, especially at low current densities, due to the formation of a passive layer on the aluminium that hinders the dissolution of the bipolar electrode.

Development of pilot scale nanofiltration system for yeast industry wastewater treatment

The treatment of the yeast industry wastewater was investigated by nanofiltration (NF) membrane process on a pilot scale. Two wastewaters were used as feed: (i) dilute wastewater with COD 2000 mg/L and (ii) concentrate wastewater with COD 8000 mg/L. The permeate flux, COD retention, color and electrical conductivity (EC) removal were evaluated in relation to trans-membrane pressure and long-term filtration. A linear growth in permeate flux was found with increasing in trans-membrane pressure for wastewaters. In addition, the COD retention, color and EC removal increased with trans-membrane pressure enhancement. The results obtained from the long-term nanofiltration of dilute wastewater indicated that the permeate flux decreased from 2300 L/day to 1250 L/day and COD retention increased from 86% to 92%. The quality of the permeate in term of COD is lower than the discharge standard in river (200 mg/L). Thus, this process is useful for treatment of wastewaters produced by yeast industry.

Optimization of struvite fertilizer formation from baker's yeast wastewater: growth and nutrition of maize and tomato plants

Struvite precipitate obtained from yeast industry anaerobic effluent with high ammonium nitrogen (NH4-N) was investigated for fertilizer effect on plant growth and nutrition according to applications of N, nitrogen/phosphorus/potassium (NPK), and control. Optimum struvite formation conditions were determined via Box-Behnken design. Optimum condition was obtained at pH 9.0 and Mg/N/P molar ratio of 1.5:1:1. Under these conditions, heavy metal concentrations in the obtained struvite precipitate (except Cu) were below the detection limits. In addition to high N, P, and Mg content, energy-dispersive X-ray (EDX) analysis showed that the struvite also included the nutritional elements Ca, K, Na, and Fe. X-ray diffraction (XRD) analysis revealed the complex structures of NaAl(SO4)2(H2O)12, NaMn(2+)Fe2(PO4)3, and (Na2,Ca)O2(Fe,Mn)O.P2O5 in the precipitate. High Na(+) and Ca(2+) concentrations in the anaerobic effluent reacted with phosphate during struvite precipitation. Different applications and struvite dosages significantly affected fresh and dry weights and nutrient element uptakes by plants (P < 0.05). N, P, and Mg uptakes of plants were significantly higher at struvite ×2, ×3, and ×4 dosages compared with NPK application. For adequate nutrition and supply of optimum dry weight, struvite ×2 dosage (5.71 g struvite/kg soil) was found appropriate for both maize and tomato plants.

Electrocoagulation for the treatment of textile industry effluent--a review

Various techniques such as physical, chemical, biological, advanced oxidation and electrochemical are used for the treatment of industrial effluent. The commonly used conventional biological treatment processes are time consuming, need large operational area and are not effective for effluent containing toxic elements. Advanced oxidation techniques result in high treatment cost and are generally used to obtain high purity grade water. The chemical coagulation technique is slow and generates large amount of sludge. Electrocoagulation has recently attracted attention as a potential technique for treating industrial effluent due to its versatility and environmental compatibility. This technique uses direct current source between metal electrodes immersed in the effluent, which causes the dissolution of electrode plates into the effluent. The metal ions, at an appropriate pH, can form wide range of coagulated species and metal hydroxides that destabilize and aggregate particles or precipitate and adsorb the dissolved contaminants. Therefore, the objective of the present manuscript is to review the potential of electrocoagulation for the treatment of industrial effluents, mainly removal of dyes from textile effluent.

COD fractionation and biological treatability of mixed industrial wastewaters

This study was conducted at a centralized wastewater treatment plant that receives discharges from nearly 160 industries. The chemical oxygen demand (COD) was fractionated for two objectives: delineation of the limits of the activated sludge process being used at the plant, and evaluation of the potential environmental impact of the treated effluent. Physico-chemical analyses, respirometric and biodegradation tests, as well as COD fractionation were carried out. Molasses-wastewaters were determined to be the major contribution to the plant. The influent was dark brown in color, with a relatively high content of both organics (2503 mg/L COD) and salts (5459 μS/cm conductivity), but a low biochemical oxygen demand (568 mg/L BOD(5)) and BOD(5)/COD ratio (0.24). The degradability of the organics was limited by the high content of inert soluble COD (S(I)). The COD fractionation pattern was 40-20-40% for S(I), X(I) (inerts) and S(H) (soluble hydrolyzable), respectively. More than 90% BOD(5) removal was obtained, which was sufficient for the plant to meet the national Standards. However, the effluent discharged into the river was intensely colored and polluted (>1000 mg/L COD, >5000 μS/cm), emphasizing the need for legislation regulating COD, color and salinity, and for upgraded treatment methods worldwide for molasses wastewaters.