Wastewater Treatment: Industrial and Anaerobic

Wastewater treatment is a process of cleansing wastewater, by removing contaminants from it, in order to produce a waste stream or a sludge which can be either discharged in the environment or reused. There exist various methods of wastewater treatment, which can be broadly categorized in three groups - physical, chemical and biological.

Industrial Wastewater

Industrial wastewater is the water contaminated due to industrial or commercial activities by humans. These sources of water pollution range from the iron and steel industries to food processing units. The cooling water used in the iron and steel industry is contaminated with products such as cyanide and ammonia. In mines and quarries, slurries of rock particles are the prime contaminants of water. Though the wastewater produced in the food processing industry is biodegradable and non-toxic, it has high concentration of biochemical oxygen demand and suspended solids. In the organic chemicals industry, water is contaminated by solvents, cleaning agents, by-products and washing or cleaning agents. According to the United States Environmental Protection Agency, even traces of mercury have been found diluted in industrial wastewater.

Industrial Wastewater Treatment

The process of cleansing wastewater which is contaminated by industrial activities is known as industrial wastewater treatment. These contaminants include asbestos, lead, ammonia, solvents, etc., which are harmful for humans and animals alike. The process includes sending this wastewater to water treatment plants to treat it before it is released into the environment. Simple sedimentation techniques are used to remove solid contaminants such as sludge. A large part of industrial wastewater includes oil and grease traces which can be removed by skimming devices. Biodegradable organic material present in the wastewater is most often treated by activated sludge or trickling filter methods. It is also possible to burn dissolved organics by the Advanced Oxidization Process. Neutralization process is used to treat acids and alkalies present in the wastewater, but this may require further treatment because frequent neutralization forms a precipitate which may be equally toxic. Metal contaminants can be precipitated from the wastewater either by changing its pH value or using other chemicals.

Anaerobic Wastewater Treatment

In the anaerobic treatment method, biological agents are used to remove the contaminant from water in the absence of oxygen. These biological agents include microorganisms which break down biodegradable material present in sludge after it is filtered from polluted water. The process is also known as anaerobic digestion, as the microorganisms digest the pollutants in the water. The method is an important component of biological wastewater treatment system. The anaerobic process takes place in huge sealed tanks. In the initial stage, the microorganisms breakdown the sludge and convert it to organic acids, carbon dioxide, hydrogen and ammonia, while in the later stages the sludge remains are converted to biogas by methanogen, a single celled microorganism. This biogas consists of methane and carbon dioxide. Low gas emissions make it one of the most widely used process. The biogas produced by this process can be utilized as an additional source of power. This plain technology is highly efficient method of treating wastewater, and is known to reduce excess sludge production by approximately 90 percent.

Industries play a vital role in the development of a country, so instead of complaining about ill-effects of industrial water pollution we should develop methods of curbing it. One such method is anaerobic wastewater treatment. Though simple, it is one of the most efficient methods of water treatment, and hence widely popular. In the United States, this method is widely used in municipal wastewater treatment plants.