Introduction: The aim of this essay is to examine how bio-hydrogen production processing technology will impact and make vital changes to the life of Hong Kongers. Over the past three decades, scientists have endeavored to think about different wastewater treatment methods that could facilitate the improvement of water quality and the production of a renewable energy source (Fang and Liu 2001). To achieve this, the production of biohydrogen from wastewater has been developed in recent years. This essay begins by explaining the principle of this new type of wastewater treatment method and how it is designed to replace the old one in the next 50 years. The second part of this essay focuses on some of the ways in which biohydrogen production contributes to the lifestyle of Hong Kongers, focusing particularly on its applications and its crucial role in providing a very important source of energy, hydrogen. Finally, it will conclude by discussing whether this method could one day replace the old one and bring us the greatest benefits. Scientific Background Living in this modern and well-developed city, Hong Kong residents have a great demand for better quality water. A well-organized wastewater treatment system is therefore very important. In practice, wastewater is purified by different microorganisms to decompose organic pollutants. This is because they are ubiquitous, very efficient and easy to control. From the late 1980s, methanogenic wastewater treatment became the main type of wastewater treatment method (Horan. 1990). It works by anaerobic respiration of several different types of bacteria and archaea to decompose organic substances present in wastewater and produce methane as the main product (Fang and Liu 2001). Although...... middle of paper...... Biological waste treatment. The Cromwell Press; 2001. 78-84 pHart, D. Hydrogen Power: the commercial future of the “ultimate fuel”. Financial Times Energy Publishing, London 1997 Horan, NJ: Biological wastewater treatment systems: theory and operation. Thomson Press (India) Ltd; 1990. 124-132 pRocha, JS, Barbosa, MJ and Wijffels, RH (2001). Production of hydrogen by photosynthetic bacteria. In: BioHydrogen, OR Zaborsky, JR Benemann, J. Miyake and AS Pietro, (eds.), Plenum Publishing, New York, pp. 3-30Santhanam KSV, Miri Massoud J., Bailey Alla V., Takacs Gerald A.: Introduction to hydrogen pedagogy. Roman J. Press; 2009. 32- 35 pOffice of Energy Efficiency (EMSD) Electrical and Mechanical Services Department. Energy end use data in Hong Kong. [Internet] 2011: 5 p.m.-10 p.m.: [cited October 4, 2011]. Available at: http://www.emsd.gov.hk