Chapter 13 - Integrated technologies for the treatment of and resource recovery from sewage and wastewater using water hyacinth

Abstract

Water hyacinth (Eichhornia crassipes) is a large vascular floating aquatic plant adaptable to a variety of environments. Water hyacinth is considered to be one among the top 10 invasive weeds as it has high yield and vigorous reproductive capacity. Water hyacinth is an excellent agent for controlling water pollution. Due to its strong capacity to absorb nutrients and pollutants from eutrophic/polluted waters, great adaptability, relatively easy harvesting, and low maintenance costs compared to submerged plant species, water hyacinth is an excellent candidate for remediation of eutrophic and polluted waters, including sewage. Water hyacinth has a great potential to absorb and adsorb nutrients such as nitrogen, phosphorous, and heavy metals present in polluted wastewaters. Therefore, water hyacinth is a valuable resource to clean polluted lakes that are an increasing urban menace, into potential recycling systems where the pollution is treated, and also acts as bio-products generation sources. This is a highly efficient approach to achieve circular bioeconomy by tackling pollution and generating valuable products in the process. Further, the highly invasive weed water hyacinth can be utilized for the generation of biofuels such as biogas and biohydrogen via anaerobic digestion process, dark fermentation along with the generation of organic fertilizer. For instance, 1ha of water hyacinth can produce 8550m3of methane gas that can support four households with an averaged energy budget for a year. Further, water hyacinth can be composted for the generation of organic fertilizer via aerobic or anaerobic composting. This chapter explores the various characteristics of water hyacinth and the methods available for processing its biomass for various applications including biogas production. There are numerous ways to make use of water hyacinth but the implementation of the process is dependent on the availability of easy and mechanized harvesting procedures, availability of land, finances, and proper channel for the sale of the products produced from water hyacinth. Therefore, this chapter describes the numerous ways of valorizing water hyacinth, which may have a huge potential to create niche in the circular bioeconomy.