Recent Developments of Membrane Technology for Wastewater Treatment

The worldwide one major and important issue is the increasing shortage of freshwater. Water is polluted by various category of pollutant such as heavy metal, organic toxic chemical, dyes and others. In such situation providing better solutions for water treatment is a major challenge for researchers. Various techniques have been used in wastewater treatment applications but among those techniques the membrane technology is the most promising technology. This chapter contains recent progress of membrane technology for advanced wastewater treatment, is systematically summarize. This review includes introduction about different membrane technology such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO). Current status of each membrane separation techniques, membrane cleaning techniques, challenges and promising solutions for various wastewater treatment have been discussed.

A Statistical Approach to Model Selection for Dynamic Adsorption Columns

A variety of models have been used to describe and predict breakthrough curves for dynamic adsorption systems, in order to scale up laboratory and pilot plant systems. There are however limitations in the applicability of existing models. The study is aimed at providing unambiguous approaches in selecting the best performing model between Thomas, Yoon-Nelson and Bohart-Adams (B-A) models for three dynamic adsorption systems. Three approaches were implemented in this study using published experimental data of three adsorption systems. The first approach was the application of statistical analysis between actual and predicted breakthrough curves without modifying the models. The second and third approaches were application of local mean values (LMV) and global mean values (GMV) of empirical constants to predict breakthrough curves. Predictive and generalization performances of the three models were evaluated using the statistical criteria of Mean Absolute Error (MAE), Root mean Squared Error (RMSE) and Correlation Coefficient (R2).

Research Progress of Advanced Oxidation Water Treatment Technology

The rapid development of the industry has brought environmental deterioration. The contradiction between industrial development and environmental protection has become increasingly prominent. How to degrade various complex pollutants in water effectively is one of the keys to solve this contradiction. Reasonable treatment and disposal of pollutants to make them harmless to the environment has important practical significance. Advanced oxidation Processes (AOPs) has been gradually applied in the field of water treatment due to its advantages of high treatment efficiency, strong oxidation intensity, no secondary pollution and its capacity to degrade varieties of organic pollutants from wastewater. The oxidative degradation mechanism of AOPs was analyzed in this paper. The future development trend of the advanced oxidation technology was prospected, and the best treatment method for water treatment technologies was sought.

Electrochemical Oxidation of Perfluorooctanoic Acid (PFOA) from Aqueous Solution using Non-Active Ti/SnO2-Sb2O5/PbO2 Anodes

In this study, electrochemical oxidation of perfluorooctanoic acid (PFOA, C7H15CO2H) from aqueous solution was examined in terms of PFOA and total organic carbon (TOC) removal by using Ti/SnO2-Sb2O5/PbO2non-active electrodes. The effects of operating parameters: initial pH (pHo), current density (j), and electrolyte concentration (m) at different time intervals were examined. Specific energy consumption (SEC) was used to determine the process proficiency. The C-C bond between C7F15 was first cleaved and thendegraded into fluoride ions (F−) and short carbon-chain per-fluorinated carboxylic acids (PFCAs) ((∼C2−C7) such as perfluoroethanoic acid (PFEA: C2F5CO2H), perfluoropropanoic acid (PFPA: C3F7CO2H), perfluorobutanoic acid (PFBA: C4F9CO2H), perfluoropentanoic acid (PFPeA: C5F11CO2H), perfluorohexanoic acid (PFHxA: C6F13CO2H), perfluoheptanoic acid (PFHpA: C7F14CO2H). These intermediates by-products were determined using the gas chromatograph-mass spectrometry (GC/MS) analysis. The rate of PFOA decomposition was followed the pseudo-first-order kinetics. About 82%TOC and 94% PFOA removals were formed at the optimal condition of pHo = 3.58, j=168.34 Am-2, and m = 250 mgL-1 at 120 min of electrolysis with SEC = 593 kWh/kg TOC. A plausible degradation mechanism was also proposed at the optimal treatment condition.

Sustainable Organo-Inorganic Metal Composites for Catalytic Degradation of Industrial Persistent Toxic Substances and Energy Storage

Colossal quantity of wastewater contaminated with persistent hazardous substances and degradable toxic compounds to the atmosphere are generated annually. Amongst the particular pollutant, chemicals, organic dyestuffs are of a considerable significance by virtue of its applications in fibers, fabric, coloring element, printed matter and manuring production. The present chapter comprises a complete perspective of green and sustainable organic-inorganic metal nanocomposites for heterogeneous chemical curtail of precarious organic noxious tinge (Chromotrope-2R, Eosin-Y and Methylene Blue) and energy storage (H2 and C2H4). The nanocomposites were designed by simple strategy adopting nanostructured porous carbon material developed from reasonable pyrolysis fuel oil (PFO) related pitch remains.

Hydrolytic Acidification-Two Stage EGSB-A/O Combined Process for Pesticide Wastewater Treatment

The wastewater produced by a chemical enterprise in Ningxia has the characteristics of high COD, high salt content, and high ammoniacal nitrogen. The biodegradability of the wastewater is poor due to presence of higher concentration of pollutant. The scale of first stage of treatment was 400m3/d. The wastewater of different characteristic was collected and treated separately. The combined process of "micro electrolysis + Fenton oxidation + coagulation precipitation + evaporation crystallization" was used to pretreat the wastewater containing high salt and high COD. The main process was "hydrolytic acidification + two-stage Expanded Granular Sludge Bed (EGSB) + two-stage advance Fenton oxidation (A/O)". The final concentrations of effluent COD, NH3-N and TDS are 376 mg/L, 34.74 mg/L, and 442 mg/L, and the removal rates are 99.9%, 81.3%, and 99.9%, respectively. The environmental, engineering and economical (3E) practices showed that the combined process has stable operation, strong impact resistance, and high reduction of COD in the effluent.

Photocatalytic Degradation of Levofloxacin by Cu doped TiO2 under Visible LED Light

Degradation performance of Cu-TiO2 photocatalytic materials against a widely used antibiotic drug levofloxacin (LFX) was investigated under visible LED light source of 40 W. Cu-TiO2 (0.25-1.0 wt%) nanomaterials are prepared through reverse micelle mediated modified sol-gel method. Characterization of synthesized Cu-TiO2 samples are performed by XRD, UV-Vis, and DLS techniques. The doping of 0.5 wt% copper in TiO2 shown lower crystallite size (5.79 nm) and visible light absorption characteristics with energy band gap of 2.84 eV. 0.5 wt% Cu-TiO2 photocatalyst has shown significant LFX degradation of 75.5% with catalyst loading of 1 g/L and initial pollutant concentration of 50 mg/L.