**Preface to "Wastewater Based Microbial Biorefinery for Bioenergy Production"**

This book is on the topic of wastewater to bioenergy. Book provides information on recent technological advancements in wastewater-based biorefinery for bioenergy production. The intent is to provide overall information to readers on possible approaches in wastewater treatment with simultaneous energy production. There are ten chapters in this book that discuss about the characterization of wastewaters, compositions, challenges in treatment, resource recovery, and bioenergy production. The first chapter describes types of wastewaters, their source, and their compositions. An overview of various possible approaches for resource recovery from wastewater and production of biofuels such as biogas, bioethanol, biodiesel, microbial fuel cell, and direct conversion of sludge wastes using gasification, pyrolysis process is discussed. Chapter 2 discusses that cost associated with wastewater has become a key issue in wastewater managemen<sup>t</sup> technology. This chapter provides a bibliometric analysis of publications in the Web of Science database on wastewater treatment costs in the period 1950–2020. The findings of this study reveal the leading countries in this field of research (China, USA, India, Spain, and the UK). Chapter 3; utilization of microalgae provides a sustainable approach for wastewater treatment and bioenergy production simultaneously. Microalgae can remove nutrients from the wastewater whilst capturing carbon dioxide from the atmosphere. The resulting biomass is employed to generate biofuels, which can run fuel cell vehicles of zero-emission, power combustion engines, and power plants. By cultivating microalgae in wastewater, eutrophication can be prevented, thereby enhancing the quality of the effluent. Chapter 4 discuss about microbial fuel cell experimental setup for bioelectricity production using seafood waste as raw material. Chapter five represents a recent update on biohydrogen production using wastewater-based microbial electrolysis cells (MEC). The present limiting issues for effective scaling up of the manufacturing process include the high manufacturing costs of microbial electrolysis cells, their high internal resistance and methanogenesis, and membrane/cathode biofouling. The challenges in the evolution of microbial electrolysis cell technology in terms of hydrogen yield, operational aspects that impact total hydrogen output in optimization studies, and important information on the efficiency of the processes are discussed. Chapter 6 discuss about a combined approach of anaerobic digestion (AD) and MEC on waste treatment and energy production. The use of MEC supported anaerobic digestion process could increase overall energy production and organic removal. Chapter 7 reports discuss about a method to reduce hydrogen sulfide production during anaerobic digestion and conclude that the addition of waterworks sludge containing iron to a digester for the removal of dissolved hydrogen sulfide is a technically and economically good alternative when producing biogas. Chapter eight is about biofilm a challenge in wastewater treatment that cause many serious problems, such as chronic infections, food contamination, and equipment corrosion. Biofilm formation and growth are complex due to interactions among physicochemical and biological processes under operational and environmental conditions. In this chapter advanced numerical modeling techniques using the lattice Boltzmann method (LBM) are enabling the prediction of biofilm formation and growth and microbial community structures is discussed in detail. Chapter 9 discuss problems related to environmental pollution caused by enhanced energy consumption and emphasize that by improving the efficiency of energy utilization this problem can be overcome. The last chapter defines the water and wastewater sector as an important lifeline upon which other economic sectors depend and securing this sector's critical

infrastructure is therefore important for any country's economy. This chapter provides a case report on South Africa strategy to contextualize the water and wastewater sector's cybersecurity responsibilities within the national cybersecurity legislative and policy environment.

> **Shashi Kant Bhatia** *Editor*
