Methane recovery from water hyacinth through whole-cell immobilization technology

Environmental challenge vis a vis opportunity: the case of water hyacinth

Water hyacinth (Eichhornia crassipes) is a noxious weed that has attracted worldwide attention due to its fast spread and congested growth, which lead to serious problems in navigation, irrigation, and power generation. On the other hand, when looked from a resource angle, it appears to be a valuable resource with several unique properties. As a result, research activity concerning control (especially biological control) and utilization (especially wastewater treatment or phytoremediation) of water hyacinth has boomed up in the last few decades. Investigations on biogas/compost production from water hyacinth have also come up very well mainly from few research groups in India. This review presents a comprehensive view of the research related to water hyacinth with special emphasis on the recent investigations on water hyacinth control and utilization technologies conducted in the last 2-3 decades. Based on these significant research achievements, now it is desirable to identify a management strategy so that the excessive growth can be controlled and the plant can be used in beneficial ways. In the rural areas, water hyacinth could be used in an integrated manner for decentralized wastewater treatment systems coupled to biogas and compost production from the resulting biomass. There is a need to work out the techno-economic viability of such integrated model systems.

Microbial attachment and growth in fixed-film reactors: Process startup considerations

Optimal steady-state performance of any biofilm reactor requires a fully developed and mature biofilm. During fixed-film reactor startup phase, biofilm is in process of development and accordingly, process performance is difficult to quantify. Environmental, cellular and surface factors greatly influence the process of biofilm formation during reactor startup. Improved knowledge of nutritional, toxicological and environmental requirements of wastewater degrading microorganisms has helped define optimal microbial growth conditions. In case of anaerobic fixed film reactors the startup is hindered by low microbial growth rates, strict environmental requirements and limited ability of methanogens to adhere and form fixed biofilms. These obstacles could be overcome by proper support media selection and formulation of appropriate inoculation procedures and startup strategies.