**Abstract**

Pollution caused by chemical and dairy effluent is a major concern worldwide. Dairy wastewaters are the most challenging to treat because of the presence of various pollutants in them. The characteristics of effluent like temperature, color, pH, Dissolved Oxygen, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), dissolved solids, suspended solids, chloride, sulfate, oil, and grease depend solely on the volume of milk processed and the form of finished produce. It is difficult to select an efficient wastewater treatment method for the dairy wastewaters because of their selective nature in terms of pH, flow rate, volume, and suspended solids. Thus there exists a clear need for a technology or a combination of technologies that would efficiently treat the dairy wastewaters. This chapter explains the energy-generating microbial fuel cell or MFC technologies for dairy wastewaters treatment having different designs of MFCs, mechanism of action, different electrode materials, their surface modification, operational parameters, applications and outcomes delivered through the technology in reducing the COD, BOD, suspended solids and other residues present in the wastewaters. The chapter also elaborates on the availability of various natural low-cost anode materials which can be derived from agricultural wastes. The current chapter elaborates on MFC technology and its tools used for dairy wastewater treatment, providing useful insight for integrating it with existing conventional wastewater treatment methods to achieve the degradation of various dairy pollutants including emerging micropollutants.

**Keywords:** dairy wastewaters, chemical oxygen demand, microbial fuel cell, electrode materials, surface modification

#### **1. Introduction**

In most countries, the dairy industry has shown tremendous growth in size and volume and is considered to be one of the largest sources of wastewater production [1]. With the swift industrialization that took place in the last century [2] and with the increased milk production rate (approximately 3% annually), dairy processing is generally regarded to be the biggest industrial wastewater source based on food production, especially in European areas [3–5].

The dairy industry is regarded as one of India's prime food industries and India ranked 1st among all the nations for milk produce [6]. The nuanced essence of

wastewater from the dairy industry lies in the presence of carbohydrates, proteins, and fats. 2–2.5 L of wastewater is generated during the processing of every liter of milk [7]. A large number of industries are located around river banks and due to lack of stringent rules and regulations, a large volume of dairy wastewater is released without treatment which goes unutilized and pollutes the environment [8]. Dairy industries are also the potent source for various emerging contaminants specifically estrogens which find their way into the environment through wastewater effluents coming out from dairy industries and livestock activities. The fate of these emerging contaminants is recognized as an issue of public health and environmental concern. The current wastewater treatment technologies are not efficient enough for the removal of these pollutants as these are not monitored regularly due to the lack of stringent rules and regulations for these contaminants. Therefore there is a need to find an innovative technology that serves the purpose. Microbial Fuel Cell (MFC) treatment has gained appreciable interest because of its ability to treat wastewaters and simultaneously leading to the generation of power. This property of the MFC technology makes it suitable for the elimination of such recalcitrant pollutants from dairy wastewater making it sustainable in nature.
