Advantage And Disadvantage Of Waste Management

Hazardous waste management is defined as the collection, treatment and disposal of unwanted material that poses the threat to the environmental chemical under managed conditions. In the hazardous management system, the treatment technologies are an inevitable method for a waste management stream. Treatment process is a significant method used to minimise the amount of hazardous waste produced and recover useful products. It can be classified into chemical, physical and biological methods. One of the best ways to get rids of waste is through chemical treatment process. Chemical treatment methods mostly use different properties of chemical to alter the characteristic of hazardous element into less hazardous elements. It is usually required an

Such waste can be chemically neutralised. The acidic waste are generally neutralised with slaked lime in a continuous stirred reactor. In this reactor, the rate of the slaked lime added is mostly controlled by feedback control system to maintain the pH value. Whereas, alkaline wastes are neutralised by adding sulphuric acid or hydrochloric acid. However, for some application acetic acid is more preferable compared to sulphuric acid or hydrochloric acid due to it non-toxic and biodegradable characteristics. Besides, alkaline waste can also be neutralised through bubbling of carbon dioxide gases to form carbonic acid. One of the advantages of carbon dioxide gas is that it is readily available in the exhaust gas at any combustion process.

On the top of that, chemical precipitation is also one of the techniques that can be applied to liquid waste stream that contained hazardous compounds. It is very effectively in removing or eliminating the heavy metals that dissolved in the waste stream. The solubility of the heavy metal can be decreased by properly adjusting the pH value. For examples, lime is commonly used to the precipitate the metals ion into insoluble metal

The main purpose of flocculation is to form a group of solid particles using flocculating agents and coagulants. Coagulant is a component that used to neutralize the negative charge of a particle, which at the same times destabilizes the forces between colloids. Coagulation and flocculation are always applied subsequently in a water pre-treatment process before a physical separation process. The coagulation- flocculation method can speed up through sedimentation process by removing of nitrous & phosphoric contents and decreasing BOD7. The common reagents which can be used as flocculating agents are aluminium salt and ferric salt. For instance, poly-aluminium chloride, aluminium sulphate, ferric sulphate, ferric chloride, and sodium