Direct flocculation process for wastewater treatment

Abstract

Flocculation remains as the conventional but most reliable mechanism for suspended solids removal in wastewater treatment system. The long-chain polymers or polyelectrolytes, derivatives of hydrocarbon, are employed as flocculants or sometimes being termed as coagulant aids. This chapter will first introduce the basic principle of flocculation followed by a detailed description on the difference between coagulation-flocculation and direct flocculation. Emphasis on single and dual polymer systems for direct flocculation process is also presented with a case study. The Population Balance Model (PBM) used to simulate the evolution of floc-size distribution to investigate the efficiency of direct flocculation process is also reviewed in this chapter. Flocculants come with many forms and they are classified in terms of molecular weight, physical form, type of charge, and charge density. Thus, flocculants classification, their commercial availability, and applications are included to give a practical guide for the users. Industrial applications of direct flocculation to replace the conventional coagulation-flocculation mainly in ceramic and tiles, food, oleo-chemical, petrochemical, slaughtering house, rubber and latex, textile, paper mill, and packaging industries are investigated. The investigation on direct flocculation in terms of dosage, treatment efficiency, and cost-effectiveness are presented. A new technique of simultaneous adsorption-flocculation for boron removal from wastewater by using palm oil mill boiler (POMB) bottom ash and flocculant is discussed at the end of this chapter.