15 - Application of dairy sludge derived products for removal of pollutants from the industrial effluents: A way to sustainable disposal

Abstract

Effluents discharged from electronics manufacturing industry, thermal power plants, electroplating industries, mining, and tanneries are the prime sources of toxic heavy metal pollutants that contaminate freshwater bodies and posing risks to living organisms and the environment. Besides these, the wastewater discharged from textile, ceramic and leather industries contains various toxic high colored organic dyes that can act as a mutagen or carcinogen even at lower concentrations affecting mankind and aquatic organisms. Therefore, it is necessary to treat these effluents coming from industries containing toxic heavy metals and carcinogenic dyes by industry or by government mechanism before discharging them into water bodies. Easy availability and the presence of several functional groups in biowastes such as cheese, whey protein make them remarkable renewable adsorbents that can be applied for adsorptive removal of heavy metals and dyes from contaminated water. Major water pollutants are heavy metals and portable water polluted with higher concentrations of heavy metals, i.e., above the permissible limit recommended by WHO could induce cancers, diabetes, hypertension, kidney disorders, lung diseases, brain damage and may even be fatal to living organisms. Secondly, dyes are the most common dangerous pollutants found in industrial effluents. These water-soluble organic dyes decompose under light or oxidant agents and curtail photosynthesis in aquatic plants. Moreover, cationic dyes are more toxic than anionic dyes because they interact with negative charges on surface of cell membrane and penetrate the cell membrane of aquatic organisms. Among numerous chemical, physical and biological processes available to treat wastewater, adsorption process is found to be a simple, economical, efficient, flexible, and preferred physicochemical treatment method to effectively treat many industrial wastewater before reaching the natural environment. Surface functionalization or coating or surface modification of biowaste adsorbent is essential to enhance its adsorption capacity. In recent years many researchers focus on using modified protein biowaste as adsorbents due to their superior biodegradability and excellent biocompatibility. Cheese whey protein is the biowastes produced as a major by-product in the dairy industry that is discharged in the dairy wastewater. With the above considerations, the present chapter aims to highlight the efficacy of renewable adsorbant for the adsorption of both cationic and anionic heavy metals and dyes on pretreated protein. This chapter also deals with characterization methods to study the morphology of the adsorbent, change in the surface charge, and functional groups involved in adsorption. The later part of the chapter reviews the successive adsorption behavior of anionic and cationic heavy metals and dyes on the biowaste adsorbents using adsorption isotherm models and kinetic analysis. The objectives of the present chapter, therefore include evaluation of the efficacy of dairy processing sludge in the removal of pollutants from wastewater, highlighting the possible mechanisms involved in adsorptive removal of pollutants, identifying the parameters that enhance the removal capacity of the adsorbents, and proposing a regeneration mechanism for reuse of the dairy processing sludge derived products. This chapter provides plausible approaches for the efficient utilization of dairy sludge for wastewater purification.