Industrial solid waste management in wastewater and sewage treatment plants

Industrial solid wastes, unlike liquid effluents and gaseous emissions, receive relatively less attention in terms of treatment, reuse, recycle and recovery of useful by-products. These wastes have great potential for recovery and reuse. As a matter of fact, these so called “wastes” are actually right materials in wrong place. The only popular method to dispose solid wastes is landfill which is not compatible with all kind of wastes like chemical and radioactive solid wastes so exploration of newer kind of waste disposal techniques are needed. The paper provides an insight into different ways and means used by scientists and engineers to minimize pollution of our natural resources and their over exploitation. Sewage Treatment Plants (STP) yield mostly organic solid wastes unlike wastewater treatment plants which deal with inorganic or metallic wastes. Hence we classify the solid wastes and their process to be followed for disposal. Predominantly organic wastes can be effectively treated by biological means to yield useful end products like methane gas as fuel and digested slurry as soil conditioner. Such methods are unexploited and are in seclusion from rest the world. Such solid wastes generated in sewage treatment plants include screenings, grits and primary sludge which if discharged in same plant through common sewerage system can cause clogging due to solid wastes which have to be treated separately in septic tanks. Unit operations and processes in a Water Treatment Plant (WTP) aim at removing inorganic solid wastes such as suspended metals, iron, manganese, fluorides, arsenics etc. There have been recent developments in disposal techniques of chemicals from WTP by co-dumping them with sewage which act as a reagent in degradation and curing of sludge.