Electrochemical Treatment of Wastewater: An Emerging Technology for Emerging Pollutants

Introduction

Antibiotics are molecules that kill, or stop the growth of, microorganisms, including both bacteria and fungi. Antibiotics that kill bacteria are called “bactericidal”. Antibiotics that stop the growth of bacteria are called “bacteriostatic”. Antibiotics affect four major components and functions of cells as follows:

• a)

  inhibition of bacteria‘s cell wall synthesis; this class of antibiotics includes vancomycin and β-lactam antibiotics such as penicillins, cephalosporins and carbapenems,

• b)

  inhibition of protein synthesis including tetracyclines, aminoglycosides, macrolides and chloramphenicol ;

• c)

  Cell membrane; and

• d)

  DNA synthesis inhibitors such as fluoroquinolones and sulfonamides that inhibit folic acid synthesis.

Antibiotics contributed over years in bacterial infections control. These drugs have an important role in the rise of life expectancy. Despite all the developments in antibiotic industry, infectious diseases remain the second cause of death worldwide; this is due to the development of antibiotics resistance organisms, which decreased current antibiotics effectiveness (Salma and Rafik, 2015). Generally, there are three main ways for antibiotics to enter the environment as follows (Derakhshan et al. 2016):

• a)

  Through the excretion, industries and the entrance to the sewage network and eventually surface water or groundwater or soil. The amounts of any antibiotic’s metabolism in the human body depend on its chemical structure and also its operation in the body; and

• b)

  Through natural resources. Some different antibiotics such as beta lactams, streptomycin, amino glycosides etc. are produced by bacteria in soil.

• c)

  Through the discard of expired and unused antibiotics which may be carried through the health services, sewage or household waste. In such cases, the antibiotics are carried to landfill through the discard of waste.

The human body cells react to antibiotics in very low systemic levels. Antibiotics exist in drinking water or food can increase the levels of these compounds in body. These compounds can reach the body tissues and cause different responses from body. Low concentrations of antibiotics can act as a vaccine for bacteria and make them resistant to the antibiotics used in the treatment of diseases. The bacteria resistance can happen due to the existence of antibiotics in hospitals and health centers wastewater, sewage, soil etc. On open land, raw water and wastewater containing antibiotic, bacteria and resistant bacteria would be used for irrigation, while excess sludge is used as fertilizer. In this action, the resistant bacteria directly enter the food chain. In addition, concentrations of antibiotics less than the required rate for diseases treatment have a significant role in bacteria resistance, which can even transmit to the bacteria genetics. Literature has revealed that the chronic effects of antibiotics are more in the environment (wastewater treatment systems, surface water, etc) and hence the need for pollution reduction and the removal of these compounds from water (Derakhshan et al. 2016).

Background

Environmental pollution is a serious problem with which human is faced and due to the population growth, the importance of environmental pollution control and its exponential growth prevention is needed more than ever. Problems caused by the presence of persistent pollutants in the environment emerging pollutants require investigation to identify various techniques to treat, reduce or remove these pollutants from environment (Derakhshan et al. 2016). Pollutants in water and wastewaters can be categorized into two (conventional and emerging pollutants).