Pyrolysis of water hyacinth in a fixed bed reactor: Parametric effects on product distribution, characterization and syngas evolutionary behavior

Global impact of water hyacinth (Eichhornia Crassipes) on rural communities and mitigation strategies: a systematic review

The proliferation of water hyacinths (Eichhornia crassipes), recognized as one of the most invasive aquatic plants worldwide, presents profound ecological and socioeconomic challenges across diverse ecosystems, particularly in rural communities. This systematic review examines the extensive global impacts and explores various mitigation strategies to manage and utilize this pervasive species. Ecologically, water hyacinth disrupts aquatic ecosystems by depleting oxygen levels, obstructing sunlight, and displacing native species, which in turn compromises water quality and biodiversity. Economically, its rapid spread affects agriculture, fishing, and navigation, imposing significant costs on local economies and livelihoods. In response, this review assesses integrated management approaches combining mechanical, chemical, and biological controls that have been implemented to curb its growth. Moreover, innovative strategies that repurpose the biomass for bioenergy, handicrafts, and bio-remediation are discussed, highlighting their potential to transform an ecological menace into an economic resource. These strategies not only mitigate the plant's negative impacts but also contribute to sustainable development by providing economic opportunities and enhancing ecosystem services. This review stresses the necessity for a holistic approach to water hyacinth management that is adaptive, sustainable, and beneficial to affected communities.

Remediation and recovery of Kariba weed as emerging contaminant in freshwater and shellfish aquaculture system via solvothermal liquefaction

Fast growing Kariba weed causes major problems and pollution on freshwater and shellfish aquaculture systems by interfering with nutrient uptake of crops, restricting sunlight penetration, and decreasing water quality due to massive biomass of Kariba weed remnants. Solvothermal liquefaction is considered an emerging thermochemical technique to convert waste into high yield of value-added products. Solvothermal liquefaction (STL) of Kariba weed as an emerging contaminant was performed to investigate the effects of different types of solvents (ethanol and methanol) and Kariba weed mass loadings (2.5-10 % w/v) on treating and reducing the weed via conversion into potentially useful crude oil product and char. Up to 92.53 % of Kariba weed has been reduced via this technique. The optimal conditions for crude oil production were found to be at 5 % w/v of mass loading in methanol medium, resulting in a high heating value (HHV) of 34.66 MJ/kg and yield of 20.86 wt%, whereas the biochar production was found to be optimum at 7.5 % w/v of mass loading in methanol medium, resulting in 29.92 MJ/kg of HHV and 25.38 wt% of yield. The crude oil consisted of beneficial chemical compounds for biofuel production such as hexadecanoic acid, methyl ester (65.02 peak area %) and the biochar showed high carbon content (72.83 %). In conclusion, STL as a remediation for emerging Kariba weed is a feasible process for shellfish aquaculture waste treatment and biofuels production.

An integrated biorefinery approach for the valorization of water hyacinth towards circular bioeconomy: a review

Water hyacinth (WH) has become a considerable concern for people across the globe due to its environmental and socio-economic hazards. Researchers are still trying to control this aquatic weed effectively without other environmental or economic losses. Research on WH focuses on converting this omnipresent excessive biomass into value-added products. The potential use of WH for phytoremediation and utilizing waste biomass in various industries, including agriculture, pharmaceuticals, and bioenergy, has piqued interest. The use of waste WH biomass as a feedstock for producing bioenergy and value-added chemicals has emerged as an eco-friendly step towards the circular economy concept. Here, we have discussed the extraction of bio-actives and cellulose as primary bioproducts, followed by a detailed discussion on different biomass conversion routes to obtain secondary bioproducts. The suggested multi-objective approach will lead to cost-effective and efficient utilization of waste WH biomass. Additionally, the present review includes a discussion of the SWOT analysis for WH biomass and the scope for future studies. An integrated biorefinery scheme is proposed for the holistic utilization of this feedstock in a cascading manner to promote the sustainable and zero-waste circular bio-economy concept.

Optimisation of process parameters using response surface methodology to improve the liquid fraction yield from pyrolysis of water hyacinth

The water hyacinth has been identified as a persistent threat to the pillars of sustainability, resulting in an increased demand for cost-effective mitigation measures. Existing control measures such as chemical and mechanical methods have proved ineffective and expensive, although their use in a biorefinery is deemed sustainable. The study focused on using the response surface methodology of Design-Expert to optimise process parameters, emphasising temperature and particle size, to improve the liquid fraction yield from the pyrolysis of water hyacinths. The experiment was conducted in the temperature range of 273.22 and 676.78 °C, with a particle size range of 380 and 2620 µm, and subjected to a heating rate of 30 °C/min and a nitrogen flow rate of 25 l/min. The results suggest that an increase in temperature and particle size led to a rise in the liquid fraction and a decrease in char. The liquid fraction increased from 24.36 wt.% at 273.22 °C to 48.45 wt.% at 575 °C and reduced to 25.56 wt.% at 626.78 °C. Char decreased from 58.21 to 33.84 wt.% at 626.78 °C. Given this, the quadratic model was found fit for optimisation. Statistical analysis of variance showed good agreement between actual data and the predicted model. This study argues that the valorisation of water hyacinths, if accompanied by policies and strategies, can trigger comprehensive socio-economic and environmental benefits by implementing optimum conditions to generate an improved liquid fraction that tends to influence its commercialisation. It is envisaged that the study's findings will inform policy discussions and formulation.

Energy-efficient biochar production for thermal backfill applications

The function of engineered thermal backfills surrounding underground pipelines of the crude oil industry is to prohibit heat migration for the design period of 25 to 50 years. Biochar is suitable for reconstituting standard thermal backfill material since it is biochemically inert and has a low heat conductivity. However, the preparation of biochar from biomass involves an energy-intensive pyrolysis process. This study aims to make biochar production energy-efficient via optimizing the pyrolysis temperatures, specifically for thermal backfill applications. Ten distinct biochars were prepared by pyrolyzing two waste biomass, i.e., water hyacinth (WH) and sugarcane bagasse (SB), at temperatures ranging from 300 to 700 °C. The biochars were assessed based on their thermal conductivity, energy consumption, yield, and stability in soil for the design period. The thermal conductivity of produced biochars varied in a narrow range of 0.10 to 0.13 W m^-1 K^-1 with different pyrolysis temperatures, which is possibly due to marginal differences in their microstructure, mineralogy, and physicochemical properties. The findings revealed that the biochar produced at lowest pyrolysis temperature (300 °C) consumed least energy and produced maximum yield. However, it was not suitable for thermal backfill applications due to its inadequate carbon stability in soil. Therefore, the current study recommends a pyrolysis temperature of 400 °C for thermal backfill applications. The recommended pyrolysis temperature was found to be at least 60% energy efficient in comparison to pyrolysis at 700 °C for both the feedstocks. This study provides crucial insight into the role of pyrolysis temperature for tailoring biochar production for intended applications.

Invasive Water Hyacinth: Ecology, Impacts and Prospects for the Rural Economy

Water hyacinth (WH) is notorious for causing severe environmental degradation and being an economic burden to manage. However, it offers substantial prospects if exploited, especially by rural communities. High temperatures, eutrophic conditions and other environmental factors promote the proliferation of the plant in regions where it has been introduced. Regarded as among the world's worst invasive weeds, WH is nearly impossible to control and eradicate without an integrated approach and community participation. The effectiveness of control methods varies, yet sustained community involvement determines the long-term success of these methods. Reproducing rapidly, WH has the resource capacity to support a unique microeconomic ecosystem, incentivising WH control by generating sustainable income. The WH ecology, the socioeconomic impacts of its invasion and its various applications are reviewed, and revenue generation and cost-saving options are highlighted. A circular microeconomic model is proposed by integrating WH valorisation into the general limitations of a rural community. Empowering locals with opportunities and enticing them with potential economic gains can be a nudge towards a pro-environment behavioural change in managing WH. This would aid in upgrading local livelihoods and could foster resilience within the community in tackling both environmental problems and economic setbacks through the management of WH invasions.

Water hyacinth for energy and environmental applications: A review

This review is focused on the sustainable management of harvested water hyacinth (WH) via thermochemical conversion to carbonaceous materials (CMs), biofuels, and chemicals for energy and environmental applications. One of the major challenges in thermochemical conversion is to guarantee the phytoremediation performance of biochar and the energy conversion efficiency in biowaste-to-energy processes. Thus, a circular sustainable approach is proposed to improve the biochar and energy production. The co-conversion process can enhance the syngas, heat, and energy productions with high-quality products. The produced biochar should be economically feasible and comparable to available commercial carbon products. The removal and control of heavy and transition metals are essential for the safe implementation and management of WH biochar. CMs derived from biochar are of interest in wastewater treatment, air purification, and construction. It is important to control the size, shape, and chemical compositions of the CM particles for higher-value products like catalyst, adsorbent or conductor.

Green and sustainable zero-waste conversion of water hyacinth (Eichhornia crassipes) into superior magnetic carbon composite adsorbents and supercapacitor electrodes

Our facile approach converts embarrassing weed to value-added products through environmentally friendly routes towards zero-waste scheme.