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In this study, removal of copper from synthetic aqueous solution was done using adsorption process. The batch study was done at room temperature and analyzed using Freundlich and Langmuir isotherms. The Box–Behnken design method of response surface methodology was used to know the interactions between independent variables (pH of aqueous solution, contact time, adsorbent dose, and initial copper concentration) and response variable (copper removal). The activated Ganga sand was used as an adsorbent to make treatment in a cost-effective way. The Ganga sand was activated by using a base solution of 14 N sodium hydroxide. The synthetic aqueous solution was having copper concentration of 100 ppm. The optimum conditions for independent variables to achieve maximum removal of copper from synthetic aqueous solution were also determined. The optimum conditions of aqueous solution for pH, contact time, adsorbent dose, and initial copper concentration were obtained as 8.7, 150 min, 3.5 g/L, and 34 ppm respectively. At this optimum condition, 97.7% of copper removal was achieved. Both isotherms (Freundlich and Langmuir isotherms) were found fitted well with a good correlation coefficient (R2 > 0.95). The kinetic behavior for the responsible adsorption process was analyzed using pseudo-second-order kinetic equations. The results suggested that Ganga sand can be used as a promising economical and conventional adsorbent for copper removal.

Ozone oxidation for treatment of azo dye solution containing Remazol Black B was examined in the present study. Remazol Black B, as di-azo dye, was chosen owing to high solubility in the aquatic sources as pollutants. The effect of ozone reaction on the removal rate of color was investigated. UV–Vis spectroscopy was used to observe dye degradation. The laboratory-scale batch experiments were performed at constant 5 g/h ozone flow rate. The results with Remazol Black B synthetic dye solution designate that 94% color reduction was obtained at 25 min of ozonation. Buffering effect on the azo dye solutions was also evaluated, and the results of this study demonstrated for the removal of color and organic matters. Energy consumption of the treatment after ozone process was also estimated in this study.

In the present study, treatment of low-strength synthetic wastewater through upflow anaerobic sludge blanket (UASB)–clariflocculator integrated system was carried out. Synthetic wastewater containing sucrose as a carbon source and phosphate as a nutrient was passed through the UASB reactor followed by clariflocculator. Water treatment sludge (WTS) was used as a coagulant in the clariflocculator. Box–Behnken design methodology with response surface methodology was used for optimizing the parameters including WTS dose, hydraulic retention time (HRT) and pH of UASB reactor. The phosphate removal was considered as a response. The observed values of responses were fitted by using second-order polynomial to compute the model. The suitability of this second-order polynomial model was checked by performing ANOVA test. Fisher’s test was done to analyze the significance of each factor and interactions between each other. With this methodology, the optimum operational condition of integrated system was obtained at 20 g/L as a WTS dose, HRT 7.68 h and pH 9. The UASB–clariflocculator integrated system removed 72.5% of phosphate at this optimum condition, whereas the phosphate removal through UASB reactor alone was obtained in the range of 8–20% only. The results suggested that water treatment sludge can be used as a coagulant to enhance the removal of phosphate from UASB reactor effluent treating low-strength wastewater and integrated system can be considered as a promising alternative of conventional system for the removal of nutrient from the effluent of UASB reactor.

The lower concentration of arsenic in the groundwater is serious health concerns of the people who are continuously taking from their drinking water. In this study, synthetic arsenic-contaminated water was prepared in the laboratory with varying concentrations of arsenic (100 to 1000 μg/L) and treated by nanosize adsorbent (copper oxide nanoparticles (CuO NPs)). The colloidal and powder form of CuO NPs were synthesized in the laboratory by the hydrothermal technique on a large scale and their shape and size were confirmed by XRD, FTIR, FESEM, and HRTEM analysis. It was found 30 ± 2 nm as size and spherical shape. The equilibrium adsorption of As (III) occurred at 90 min of contact time, pH 7.5, and 4 g/L adsorbent dosage. The maximum percent removal of As (III) was reached to 97.8, 94.6, 91.5, and 88.4% at an initial arsenic concentration of 100, 200, 500, and 1000 μg/L, respectively. The adsorption of As (III) followed pseudo-second-order kinetic and Freundlich isotherm model. Moreover, the overall cost of the synthesized CuO NPs (including material, operational, manpower, and transport cost with other overhead charges) was Rs. 281.832 g(−1), which is lesser than the market price (Rs. 500.018 g(−1)). Hence, the optimized adsorption design would help for the efficient removal of As (III) from aqueous medium.

A novel cellulose and chitosan-based natural biopolymer or coagulant aids with a commercial coagulant (ferric chloride FeCl3) have been used for the removal of arsenite As(III) from synthetic tap water at 2 mg/L of initial arsenic concentration by coagulation–flocculation method. The maximum As(III) removal efficiency of 69.25% was obtained without coagulant aids at 40 mg/L concentration of FeCl3. The addition of cellulose and chitosan with FeCl3 enhanced the removal efficiency of As(III). The percentage of As(III) removal reached 84.62 and 74.87% at the concentration of 1 and 1.5 mg/L for cellulose and chitosan, respectively, with 25 mg/L of fixed FeCl3 concentration. Comparable As(III) removal efficiencies were obtained using cellulose, chitosan, and FeCl3. Moreover, As(III) removal efficiency of cellulose was significantly found greater (p

To control the total treatment cost of textile dye effluent a new advanced combined treatment technology has been investigated. Advanced oxidation processes like ozonation have much potential to degrade dye but its main drawback is high cost. To reduce the cost of ozonation for dye degradation and decolourization, ozonation followed by anaerobic biodegradation using upflow anaerobic sludge blanket (UASB) reactor was carried out. The synthetic textile wastewater containing Reactive Black 5 has been used in this study by this combined treatment process. The system of ozonation and anaerobic treatment by UASB reactor showed that the chemical oxygen demand (COD) reduction has reached to about 90% and dye removal 94% respectively. Combined treatment enhanced the overall color removal up to 10 on platinum cobalt (Pt–Co) scale. Thus the combined treatment process results in high color, COD and total organic carbon (TOC) removal efficiency which would minimize the overall treatment cost. Dye degradation products were analyzed by ion chromatography (IC) and UV–vis spectroscopy.

In the present study ozonation process was implemented to analyze the effect of ozonation time on the rate of chemical oxygen demand (COD) removal, mineralization and rate of decolorization of azo dyes. Three types of azo dyes i.e. Acid Red 14, Direct Red 28 and Reactive Black 5 were selected. Decolorization and mineralization of samples were conducted in batch scale. The COD and color removal efficiency were found to be increasing at a certain time of ozonation. The results with Acid Red 14, Congo Red and Reactive Black 5 dyes solutions lead to maximum COD reduction of 75%, 67% & 50% respectively. 93%, 92% and 94% color removal were achieved after 25 min of ozonation time of the same dyes which highlighted that ozonation process was found to be more efficient for reactive dye decolorization. Ozonation by-products analyzed by ion chromatography resulted that it partially mineralized with the formation of chloride, fluoride, sulphate, nitrate and oxalate ions. During ozonation process a rapid decrease in p...

This study evaluated the efficiency of ozonation for removal of color and chemical oxygen demand (COD) of Congo red, as an anionic dye was selected due to the complex chemical structure with di-azo aromatic group and extended application in the textile industry. The effect of ozonation time on the rate of COD removal, mineralization and rate of decolorization were studied and the result was analyzed in terms of COD and color removal efficiency. Intermediate and final by-products formed during ozonation were identified by ion chromatography (IC). Dye decomposition rate was observed by UV–vis spectroscopy. The removal of COD and color of Congo red by ozonation was performed in a batch reactor with constant ozone flow rate and concentration of 5 g/hr and 55.5 mg/L, respectively. Dye concentration was 1,500 mg/L. Decolorization and degradation of dye sample were carried out with a certain time interval and analyzed immediately. The COD and color removal efficiencies increase at specified time of ozona...