Removal Efficiency Of Total Dissolved Solids Research Articles

Removal of river water turbidity and total dissolved solids using natural coagulants derived from banana peel and Moringa stenopetala seed

ABSTRACT In this study, natural coagulants obtained from banana peel and Moringa stenopetala seed were applied to remove total dissolved solids (TDS) and turbidity from river water. Central composite design (CCD) method was applied for the operating conditions of pH (3–10), coagulant dosage (0.3–1 g/L), stirring speed (30–90 rpm), and settling time (20–60 min). The optimum conditions obtained from the numerical optimization for pH, coagulant dosage, stirring speed, and settling time were 8.52, 1.000 g/L, 33.58 rpm, and 37.92 min, respectively, with a desirability value of 0.883 when banana peel powder was used as a natural coagulant. Under those optimum conditions, the experimental results for banana peel showed 81.32 and 93.09%, removal efficiency for TDS and turbidity, respectively. Similarly, the optimum conditions obtained from numerical optimization for pH, coagulant dosage, stirring speed, and settling time were 9.99, 0.999 g/L, 30.0 rpm, and 39.96 min, respectively, with a desirability value of 0.963. Under these optimum conditions for M. stenopetala seed powder, the experimental results showed 83.64 and 95.13%, removal efficiency for TDS and turbidity, respectively. Overall, M. stenopetala seed powder shows a higher potential for TDS and turbidity removal efficiency than banana peel powder.

Exploring Innovative Applications of Evaporative Cooling for High-Total-Dissolved-Solids Produced-Water Treatment

Summary This research delves into the pioneering application of evaporative cooling (EC) to address the challenge of reducing total dissolved solids (TDS) in produced water generated during hydraulic fracturing operations in the Permian Basin. In this study, we used a meticulously designed laboratory-scale EC system comprising three cooling pads, a fan, a water reservoir, and a pump. Through a systematic series of experiments, both synthetic and authentic produced-water samples were treated, shedding light on the potential of this novel approach. The EC system efficiently processed untreated produced water, circulating it through the cooling pads, all while closely monitoring crucial variables such as inlet and outlet temperatures, relative humidity, and remaining water volume, utilizing a state-of-the-art temperature and humidity meter. Control experiments were systematically conducted to probe the influence of varying salinities, achieved by introducing NaCl into distilled water, encompassing a wide range from 0 ppm to 70,000 ppm. In addition, we extended our evaluation to real produced-water samples collected from diverse regions within the Permian Basin (Delaware, Northern Midland, and Southern Midland), reflecting the system’s capability to manage high salinity and the diverse impurities inherent to oil and gas production. A comparative analysis of energy consumption was undertaken, positioning EC against conventional thermal evaporation techniques. The findings revealed a compelling insight that differences in EC efficiency between synthetic and real oilfield brines were primarily attributed to the presence of sodium (Na+) and chlorine (Cl-) contents rather than the overall TDS concentration. Across all experiments, the system consistently achieved remarkable TDS removal efficiencies, hovering around the 100% mark for both synthetic and authentic produced-water samples. Moreover, the study unveiled a significant advantage of EC, as it proved to be significantly less energy-intensive when juxtaposed with conventional thermal evaporation methods. In addition, our experiments revealed that divalent ions like CaCl2 tend to lower the treatment efficiency compared to monovalent ions, adding a crucial dimension to our understanding of EC in water treatment. The EC system demonstrated remarkable efficiency, achieving nearly 100% TDS removal in both synthetic and real samples while being significantly less energy-intensive than conventional thermal evaporation methods. This research underscores EC’s potential as an effective, sustainable, and economical solution for high-TDS water treatment, with promising applications in industrial settings. The study also draws parallels between EC and air conditioning systems, suggesting its versatility in various industrial applications.

Harnessing graphene oxide-enhanced composite metal-organic frameworks for efficient wastewater treatment

The issue of carwash wastewater emerges as a pressing environmental concern on a global scale, primarily due to the intricate nature of its pollutants, which makes effective treatment a formidable challenge. In the face of this complex scenario, the pursuit of an efficient treatment methodology assumes paramount importance. In response to this complex scenario, this study embarked on an exploration of a novel polymeric adsorbent material synthesized from Zeolitic Imidazolate Framework-67, Zeolitic Imidazolate Framework-8, Polyethersulfone, and graphene oxide in a fixed-bed treatment system for carwash wastewater. The investigation encompassed three distinct filter column depths, measuring 8 cm, 12 cm, and 16 cm, respectively. With an increase in filter depth from 8 cm to 16 cm, notable improvements were observed in the removal efficiencies for most contaminants. Notably, oils/grease removal showed an increasing trend with column depth, reaching 95.4%, 98.6%, and 100% for 8 cm, 12 cm, and 16 cm depths, respectively. TSS and Turbidity removal efficiencies remained consistently high at 100% across all depths, showcasing effective removal of solid particulate matter. Copper and Zinc removal efficiencies increased with deeper column depths, reaching values of 80.4%–89.9% and 79.6%–90.3%, respectively. Surfactants exhibited efficient removal, with values ranging from 90.6% to 96.6%. Total Dissolved Solids removal efficiency increased from 71.6% to 83.4% as column depth increased. Similarly, Chemical Oxygen Demand, Biochemical Oxygen Demand, total organic carbon, and phosphates removal efficiencies showed improvement with increasing column depth, reaching values of 95.4%, 98.3%, 98.8%, and 89.3%, respectively. Moreover, The composite MOF beads demonstrated significant adsorption capacities in carwash wastewater treatment, with a noteworthy 35.08 mg/g for Oils/Grease and 28.12 mg/g for Biochemical Oxygen Demand, highlighting their efficiency in removing hydrophobic contaminants and organic pollutants.The derived results highlight the potential of the composite material for carwash wastewater treatment towards advancing the field of wastewater treatment.

Optimizing Operational Conditions of Pilot-Scale Membrane Capacitive Deionization System

In this study, we developed a pilot-scale membrane capacitive deionization (MCDI) system for treating mildly brackish water and examined various operational parameters, including module arrangements, adsorption/desorption times, and flow rates. As we aimed to optimize these parameters to increase total dissolved solids (TDS) removal efficiency, the results revealed that the dual-series mode module arrangement and an adsorption time of 120 s with a flow rate of 10 L/min achieved the highest TDS removal efficiency of 99%. Energy consumption analysis showed that lower flow rates were associated with higher TDS removal efficiencies, highlighting the balance between energy consumption and water quality. This study provides insights into optimizing a pilot-scale MCDI for efficient water supply solutions, offering promise for sustainable and eco-friendly water treatment.

Environmental and Economic Evaluation of Downflow Hanging Sponge Reactors for Treating High-Strength Organic Wastewater

This study evaluated the performance of a downflow hanging sponge (DHS) in reducing the concentrations of chemical oxygen demand (COD), ammonia (NH3), total suspended solids (TSS), and total dissolved solids (TDS) in high-strength organic wastewater (HSOW). The DHS unit was composed of three segments connected vertically and operated under different organic loading rates (OLRs) between 3.01 and 12.33 kg COD/m3sponge/d at a constant hydraulic retention time (HRT) of 3.6 h. The results demonstrated that the DHS system achieved COD, NH3, TSS, and TDS removal efficiencies of 88.34 ± 6.53%, 64.38 ± 4.37%, 88.13 ± 5.42%, and 20.83 ± 1.78% at an OLR of 3.01 kg COD/m3sponge/d, respectively. These removal efficiencies significantly (p < 0.05) dropped to 76.39 ± 6.58%, 36.59 ± 2.91%, 80.87 ± 5.71%, and 14.20 ± 1.07%, respectively, by increasing the OLR to 12.33 kg COD/m3sponge/d. The variation in COD experimental data was well described by the first-order (R2 = 0.927) and modified Stover–Kincannon models (R2 = 0.999), providing an organics removal constant (K1) = 27.39 1/d, a saturation value constant (KB) = 83.81 g/L/d, and a maximum utilization rate constant (Umax) = 76.92 g/L/d. Adding another DHS reactor in a secondary phase improved the final effluent quality, complying with most environmental regulation criteria except those related to TDS concentrations. Treating HSOW with two sequential DHS reactors was economically feasible, with total energy consumption of 0.14 kWh/m3 and an operating cost of about 7.07 USD/m3. Accordingly, using dual DHS/DHS units to remove organics and nitrogen pollutants from HSOW would be a promising and cost-efficient strategy. However, a tertiary treatment phase could be required to reduce the TDS concentrations.

Evaluation of a Hybrid Moving Bed Biofilm Membrane Bioreactor and a Direct Contact Membrane Distillation System for Purification of Industrial Wastewater.

Integrated wastewater treatment processes are accepted as the best option for sustainable and unrestricted onsite water reuse. In this study, moving bed biofilm reactor (MBBR), membrane bioreactor (MBR), and direct contact membrane distillation (DCMD) treatment steps were integrated successively to obtain the combined advantages of these processes for industrial wastewater treatment. The MBBR step acts as the first step in the biological treatment and also mitigates foulant load on the MBR. Similarly, MBR acts as the second step in the biological treatment and serves as a pretreatment prior to the DCMD step. The latter acts as a final treatment to produce high-quality water. A laboratory scale integrated MBBR/MBR/DCMD experimental system was used for assessing the treatment efficiency of primary treated (PTIWW) and secondary treated (STIWW) industrial wastewater in terms of permeate water flux, effluent quality, and membrane fouling. The removal efficiency of total dissolved solids (TDS) and effluent permeate flux of the three-step process (MBBR/MBR/DCMD) were better than the two-step (MBR/DCMD) process. In the three-step process, the average removal efficiency of TDS was 99.85% and 98.16% when treating STIWW and PTIWW, respectively. While in the case of the two-step process, the average removal efficiency of TDS was 93.83% when treating STIWW. Similar trends were observed for effluent permeate flux values which were found, in the case of the three-step process, 62.6% higher than the two-step process, when treating STIWW in both cases. Moreover, the comparison of the quality of the effluents obtained with the analysed configurations with that obtained by Jeddah Industrial Wastewater Treatment Plant proved the higher performance of the proposed membrane processes.

Optimization of the biological salt removal process from artificial industrial wastewater with high TDS by Spirulina microalga using the response surface method.

This study aimed to examine the direct applicability of Spirulina maxima as a new conceptual method for removing total dissolved solids (TDS) from artificial industrial wastewater (AIW). In this study, live microalgal cells were used in a photobioreactor for TDS removal. The effects of TDS levels, pH, light intensity, and light retention time on microalgal growth and TDS removal were investigated, and optimal conditions were determined using the response surface method and Box-Behnken Design (RSM-BBD). The calculated values of coefficient of determination (R2), adjusted R2, and predicted R2 were 0.9754, 0.9508, and 0.636, respectively, which are close to the R2 values and validated the proposed statistical model. A second-order model could optimally determine the interactions between the studied variables according to the one-way analysis of variance (ANOVA). The results showed that increasing TDS levels reduced microalgal growth and TDS removal efficiency in AIW. S. maxima reduced TDS by 76% and 47% at TDS concentrations of 2,000-4,000 mg/L, respectively, when used in AIW. Maximum biomass efficiency (1.8 g/L) was obtained at a TDS concentration of 2,000 mg/L with other parameters optimized.

Thermodynamic and kinetic study of fluorinated gas hydrates for water purification

AbstractThis study investigated and compared the thermodynamic stability, kinetic behaviour, and effectiveness of a water purification process using pentafluoroethane (HFC125a) and 1,1,1,2‐tetrafluoroethane (HFC134a) as guest molecules. The hydrate phase equilibria of each fluorinated gas (F‐gas) in pure water and NaCl solution were predicted using the Hu‐Lee‐Sum correlation, which agreed well with the experimental results from our previous studies. Under the same subcooling temperature of 3 K (at 0.3 MPa), the rate of hydrate growth with HFC134a was faster than that of HFC125a in the absence or presence of NaCl. In situ Raman spectroscopy confirmed that the HFC134a and HFC125a molecules occupy only a large cage of structure II hydrate. The Raman shifts of CH and CC bands in all phases (gas, liquid, and hydrate phases) of HFC125a shifted to higher wavelengths than those of HFC134a due to the increase in the number of fluorine atoms. The change in the salinity was studied to evaluate the effectiveness of an F‐gas hydrate‐based water purification process. In addition, the desalination efficiency of the HFC134a and HFC125a hydrates was compared by separating hydrate crystals from the slurries. The results showed that the desalination efficiency (or total dissolved solids removal efficiency) of HFC134a hydrate was higher than that of HFC125a hydrate. This study proves the importance of the water purification process using hydrates.

Performance Evaluation of Textile Effluent Treatment Plant: Bangladesh Perspective

The present study was undertaken to evaluate the performance efficiency of an Effluent Treatment Plant (ETP) of a Textile industry located at Tongi, Bangladesh with biological treatment (BT) and Membrane Bio-Reactor (MBR) with an average inflow of 300 m3/hr. The effluent samples were collected from the inlet and outlet of the ETP on a weekly basis for a 4 weeks’ period and were analysed for key parameters such as colour, temperature, total suspended solids (TSS), Total Dissolved Solids (TDS), pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), and Chemical Oxygen Demand (COD). In this study, it was observed that the colour of the effluent in the inlet was dark blue and after multiple unit treatments of the colour’s final outlet the discharge, water colour was very light purple. The temperature was varied from 32.2⁰C to 34.33⁰C. The TDS was varied from 1252.5 mg/l to 1087.5 mg/l and the percentage removal efficiency of TDS was varied from 21.47% to 42.7%. The TSS was varied from 4 mg/l to 4.5 mg/l and the percentage removal efficiency of TSS was varied from 98.48% to 98.21%. The pH value was varied from 6.48 to 7.63. The DO value in the inlet was varied from 6.47 mg/l to 6.775 mg/l. The BOD was recorded from 12.75 mg/l to 17.75 mg/l and the percentage removal efficiency of BOD was varied from 89.92% to 87.24%. The COD was varied from 33.75 mg/l to 34.25 mg/l and the percentage removal efficiency of COD was varied from 91.11% to 90.5%. It is conjectured that the values of the measured parameters are seen to be within the permissible limit as per the standard of the Department of Environment (DoE) of Bangladesh.

Petroleum refinery wastewater treatment using a polysulfone-nano TiO2 hybrid membrane coupled with an ozonation process as a pre-treatment

Fouling has been the main problem that seriously hinders membrane applications for petroleum wastewater treatment. This study aimed to explore advanced membrane process integrated with ozonation as a preliminary treatment. Ozone utilization was set at a constant dose of 3000 mg/h for different ozonation times and temperatures. A longer ozonation time significantly improved the removal of pollutants. Ozonation at 30°C for 120 min removed up to 38.25% total dissolved solids (TDS), 73.33% organic compounds expressed as chemical oxygen demand (COD), 11.6% ammonia, and 62.15% total phenol. Although an increase in the ozonation temperature increased the ammonia removal by up to a remarkable 82%, it did not significantly affect the TDS, COD, and phenol removal efficiencies. Scanning electron microscope (SEM) and Fourier-transform infrared (FTIR) evaluations of the used membrane revealed that membrane fouling was caused by organic compounds consisting of hydrocarbon oil, benzene, toluene, xylene, phenol, and salt. Ozonation enhanced the permeate flux of the membrane by up to 96% and improved pollutant removal by up to 77%. The ozonation process was also responsible for the reduction of fouling resistance on the membrane surface by up to 21%.

Life cycle assessment for algae-based desalination system

To clearly understand the environmental impacts of algae-based desalination system, a life cycle assessment is undertaken by comparing four different scenarios: (1) multi-stage microalgae based desalination system without algal biomass reuse; (2) multi-stage microalgae based desalination system with algal biomass reuse; (3) hybrid desalination system with microalgae as the pre-treatment for Low Pressure Reverse Osmosis; and (4) conventional Seawater Reverse Osmosis system. It is suggested that scenarios 2 and 4 have the overall lowest and highest environmental impacts, respectively. This phenomenon is probably caused by the lower energy consumption and lower operational and maintenance requirements of high rate algal pond system. Furthermore, scenario 2 considers the algal biomass reuse to generate electricity through anaerobic digestion, which could offset the environmental impacts. It is also identified that the operational phase contributes approximately 50–60% of the total environmental impact in most impact categories for algae-based desalination system, however, the operational phase contributes around 70–80% of the total environmental impact for membrane based desalination system. A sensitivity study is undertaken to evaluate the effects of three key design parameters on environmental impact in global warming impact category. It is identified that the total dissolved solids removal efficiency of high rate algal pond plays the most important role in determining the potential environmental impacts of different scenarios. This study clearly shows that scenario 2 of multi-stage microalgae based desalination system with algal biomass reuse is the most environmentally friendly desalination approach.

Dairy wastewater treatment with bio-electricity generation using dual chambered membrane-less microbial fuel cell

Global energy requirements are mostly dependent on the fossil fuels, which eventually lead to foreseeable depletion of limited fossil energy sources. In this context, regeneration of dairy wastewater is one of the possibilities, and countries like India are progressing towards harnessing new energy sources from dairy waste water. Microbial fuel cells (MFC) have been investigated by many researchers in the past who concluded that MFCs could be applied for the treatment of liquid waste streams and also for generation of electricity. A variety of complex organic wastes and renewable biomass provide MFCs with a significant advantage over chemical fuel cells which can utilize only purified reactive fuels (e.g., hydrogen). Primary application of MFCs is its use in wastewater treatment coupled with electricity generation. The aim of this study was to test a novel Dual Chambered Microbial Fuel Cell (DC-MFC) design for dairy wastewater treatment and bio-electricity generation. Higher percentage of reduction of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) and significant electricity generation using MFCs can be achieved. This study shows a considerable reduction in biochemical oxygen demand, chemical oxygen demand and total dissolved solids (TDS). Highest COD removal achieved was 92.2%, BOD removal efficiency was 88.02% and TDS removal efficiency was 76.3%. The maximum electricity generated was 644 mV. Hence, the overall reactor efficiency is very encouraging and could be scaled up easily in the near future.

Treatment of real printing wastewater using electrocoagulation process with titanium and zinc electrodes

Electrocoagulation (EC) has numerous benefits over traditional coagulation. It is noteworthy that most researchers have studied EC using either iron electrodes or aluminum electrodes. The key objective of this study is to investigate the performance of the EC process with zinc and titanium electrodes for treating real printing wastewater through several experimental conditions. Experiments were done through batch systems. The effects of the operating variables, inclusive of varying current densities (CDs), spacing between electrodes, electrolysis time, and varying electrode materials (titanium and zinc) on the efficiency of the removal of different parameters were studied. Oil and grease, total dissolved solids (TDS), and chemical oxygen demand (COD) were among these parameters. The highest removal efficiency for COD after 90 min using a zinc electrode was approximately 50 % attained at 20 mA/cm2. For the titanium electrode, after 90 min, the highest removal efficiency for COD was 46 % attained at 15 mA/cm2. For the removal efficiency of TDS, the zinc electrode performance was better than that of the titanium electrode for every CD. After 90 min, the optimal TDS removal efficiencies were 9 % and 19 % for titanium and zinc electrodes, respectively. The titanium electrode offers the maximum efficiency of removal for oil and grease. The highest efficiencies of removal were attained at a separation distance of 4 cm. At a CD of 15 mA/cm2, the best COD elimination efficiencies using the titanium electrode at the separation distances of 6, 4, and 2 cm were 24 %, 47 %, and 30 %, respectively. At a CD of 15 mA/cm2, the best COD removal efficiencies using the zinc electrode at the separation distances of 6, 4, and 2 cm were 27 %, 41 %, and 38 %, respectively. In both the zinc and titanium electrodes, following the experiments, corrosion occurred in the anodes, which is evidence that the process of treatment took place. The EC performance was observed to be much better than that of conventional coagulation during the treatment of printing wastewater. Zinc and titanium electrodes demonstrated a good capability of removing pollutants when used in the EC process.

Removal of total dissolved solids from wastewater using a revolving algal biofilm reactor.

Total dissolved solids (TDS) comprising inorganic salts and organic matters are pollutants of concern to aquatic systems and water for human use. This work aimed to investigate the use of revolving algal biofilm (RAB) reactors as a sustainable and environmental friendly method to remove TDS from industrial effluents and municipal wastewaters. The wastewaters contained chloride, sodium, potassium, calcium, magnesium, and sulfate as the major components. The RAB reactors fed with synthetic industrial effluent with high TDS level demonstrated the best algal growth, with the highest TDS removal efficiency (27%) and removal rate (2,783mg/L-day and 19,530mg/m2 -day). A suspended algal culture system only removed 3% TDS from the same wastewater. The TDS removal by the RAB reactors was considered due to several mechanisms such as absorption by the algae cells, adsorption by extracellular polymeric substance of the biofilm, and/or precipitation. Collectively, this research shows that the RAB reactors can serve as an efficient system in wastewater remediation for TDS removal. PRACTITIONER POINTS: Total dissolved solids (TDS) in wastewater are pollutants of concern. The RAB reactors can remove TDS from various types of wastewater. The RAB reactors removed TDS by adsorbing ions elements such as Cl, Na, K, Ca, Mg, and S. The algal biomass absorbs ions through extracellular polymeric substance.

Carwash Wastewater Treatment by Electrocoagulation Using Aluminum Foil Electrodes

Large quantities of contaminated carwash wastewater are produced per day from carwash places. Extensively it contains large quantities of chemicals from detergents, oil, grease, heavy metals, suspended solids, types of hydrocarbons, and biological contents. A novel electrocoagulation treatment by foil electrodes was conducted to remove COD, turbidity, Total Dissolved Solids (TDS) from contaminated carwash wastewater and decrease its Electrical Conductivity (EC). A thin layer of aluminum foil is used as an electrode in this treatment process. The effects of different voltage and treatment times were studied. The best result was found at a voltage of 30 volts and treatment time 90 minute where the removal efficiency of COD, turbidity, TDS, and EC were 97.94%, 99.90%, 25.31%, 15.57% respectively.
 

Treatment of Saline Water Using Electrocoagulation with Combined Electrical Connection of Electrodes

Saline water treatment has become increasingly important for drinking water supplies. The aim of this study was to evaluate the ability of the electrocoagulation (EC) process with combined aluminum electrodes in removing various types of salt from water samples collected at Sawa Lake, Al-Muthanna, Iraq. The targeted types of salt include total dissolved solids (TDS), chloride salt (Cl−), bromine (Br−), and sulphate (SO42−). A bench scale consisting of combined EC configurations with static electrodes was employed under combined electrical connections. The effect of the six variables factors, such as applied current density (I), reaction time (RT), pH, temperature (T), stirring speed (Mrpm) and inter electrode distance (IED) were observed to achieve a higher removal of TDS, Cl−, Br− and SO42−. Initial results showed the following optimum operating conditions: I = 2 mA/cm2, RT = 80 min, pH = 8, T = 25 °C, IED = 1 cm and Mrpm = 500. The maximum removal efficiency of TDS, Cl−, Br− and SO42− were 91%, 93%, 92% and 90%, respectively. It can be concluded that the EC method applied in the present study was effective to removing salts from lake water.

Removing Organic Matter and Nutrients from Pig Farm Wastewater with a Constructed Wetland System.

Pollutants from pig farms in Mexico have caused problems in many surface water reservoirs. Growing concern has driven the search for low-cost wastewater treatment solutions. The objective of this research was to evaluate the potential of an in-series constructed wetland to remove nutrients from wastewater from a pig farm. The wetland system had a horizontal flow that consisted of three cells, the first a surface water wetland, the second a sedimentation cell, and the third a subsurface flow wetland. The vegetation used was Thypa sp. and Scirpus sp. A mix of soil with red volcanic rock (10–30 mm diameter) and yellow sand (2–8 mm diameter) was used as a substrate for the vegetation. The experiments were carried out in duplicate. Water samples were collected at the inflow and outflow of the cells. Two hydraulic retention times (HRT) (5 and 10 days) and three treatments were evaluated: 400, 800, and 1200 mg·L−1 of chemical oxygen demand (COD) concentration. Data was collected in situ for temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). COD, total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3–N), and total phosphorous (TP) were analyzed in the laboratory. The results showed that the in-series constructed wetland is a feasible system for nutrient pollutant removal, with COD removal efficiency of 76% and 80% mg·L−1 for a 5- and 10-day HRT, respectively. The removal efficiency for TKN, NH3–N, and TP reached about 70% with a 5-day HRT, while a removal of 85% was obtained with a 10-day HRT. The wetland reached the maximum removal efficiency with a 10-day HRT and an inflow load of 400 mg·L−1 of organic matter. The results indicate that HRT positively affects removal efficiency of COD and TDS. On the other hand, the HRT was not the determining factor for TP removal. Treatment one, with an initial COD concentration of 400 mg·L−1, had the highest removal of the assessed pollutants, allowing for the use of water for irrigation according to Mexican regulatory standards (NOM-001). The water quality resulting from treatments two and three (T2 = 800 mg·L−1 of COD and T3 = 1200 mg·L−1 of COD) did not comply with minimal requirements for irrigation water.

Study on the effect of total dissolved solids (TDS) on the performance of an SBR for COD and nutrients removal

ABSTRACTIn this study, the effect of total dissolved solids (TDS) on the performance of a sequencing batch reactor (SBR) system to treat synthetic wastewater with microbial inoculum was evaluated. The SBR was operated continuously for eight days on a 6-h cycle with anaerobic/anoxic/aerobic phases in each cycle after entering the steady state, and the influent TDS was tested at five levels, i.e., 750, 1500, 3000, 4500, and 6000 mg L−1. The results showed that only two TDS levels (750 and 1500 mg L−1) could achieve good COD removal efficiencies (94.8 and 92.2%, respectively). For TDS levels equal to, or greater than, 3000 mg L−1, a 20% reduction in COD removal efficiency resulted. Different from COD, removal of NH4+–N appeared not to be affected by the TDS content, and a removal efficiency of higher than 97% was obtained, regardless of the TDS content. However, only the lowest two TDS levels achieved high phosphate removals (>99%), and the removal efficiency dropped to 57.8 and 45.9%, respectively, for TDS levels of 3000 and 4500 mg L−1. More interestingly, a phosphate release, instead of uptake, was observed at the TDS level of 6000 mg L−1. It may be concluded that for effective phosphate removal, the TDS level in the liquid should be controlled under 1500 mg L−1, and higher liquid TDS levels were detrimental to the aerobes and could disrupt the aerobic metabolism, leading to the failure of the SBR treatment system. A tendency that raising TDS content would adversely affect the aerobic oxygen uptake rate was observed, which could also result in SBR upset. A power regression with an R of 0.9844 was established between the influent TDS concentration and the TDS removal efficiency, which may be used to estimate the SBR performance in TDS removal based on the influent TDS content.

Oxidation-coagulation-filtration processes for the reduction of sulfide from the hair burning liming wastewater in tannery

The liming wastewater in tanneries contain huge amounts of soluble sulfide; upon acidification, this produces toxic hydrogen sulfide, which is a grave environmental concern. In the present study, an approach was made to treat liming wastewater with oxidation-coagulation-filtration techniques; wastewater was treated with hydrogen peroxide to eliminate the emission of hydrogen sulfide and aluminum sulfate was used as coagulant. The physicochemical parameters of untreated liming wastewater were: sulfide 7285.2 ± 11 mg/L; pH 12.5 ± 0.2; total dissolved solids (TDS) 23.8 ± 0.3 g/L; total suspended solids (TSS) 17.8 ± 0.2 g/L; electric conductivity (EC) 40.5 ± 0.2 mS; salinity 23.4 ± 0.1 ppt; and dissolved oxygen (DO) 8.3 ± 0.1 mg/L. The physicochemical parameters of the treated liming wastewater at optimum conditions were: sulfide 81.9 ± 0.5 mg/L; pH 6.9 ± 0.2; TDS 4.5 ± 0.1 g/L; TSS 0.8 ± 0.02 g/L; EC 5.8 ± 0.1 mS; salinity 3.1 ± 0.04 ppt; and DO 7.3 ± 0.03 mg/L. The removal efficiency of sulfide, TDS, TSS, EC and salinity were 99%, 81%, 96%, 86% and 87%, respectively. The most promising outcome of this technique was the efficiency in the removal of sulfide. This simple technique for treating liming wastewater would be very effective in reducing environmental pollutants being emitted by the tanneries.

Desalination of oilfield produced water associated with treatment of domestic wastewater and bioelectricity generation in microbial osmotic fuel cell

In the present study, a novel application of microbial osmotic fuel cell (MOFC) for simultaneous treatment of real wastewater, bioenergy generation and desalination of real oilfield produced water is investigated. A three-chambered MOFC provided with forward osmosis (FO) membrane and cation exchange membrane (CEM) was inoculated with activated sludge and fueled with actual domestic wastewater. Real oil produced water having initial total dissolved solids (TDS) concentration of 49,200mg/L was used as a draw solution for the desalination mid chamber. Results revealed that maximum removal efficiency of COD from real wastewater, TDS removal efficiency from actual produced water, power density, current density, and power yield were 92%, 80%, 48.52mW/m2, 136.30mA/m2, and 7.46W/kg CODR, respectively. A mathematical model was developed to predict the performance of MOFC. It was found that the predicted results were in a good agreement with experimental results with a correlation coefficient up to 0.989, indicating the validity of the suggested model for this bio-electrochemical-osmotic system within the selected range of operating conditions.