Identifying Advanced Biotechnologies to Generate Biofertilizers and Biofuels From the World’s Worst Aquatic Weed

Water hyacinth (Eichhornia crassipes L.) was introduced as an invasive plant in freshwater bodies more particularly in Asia and Africa. This invasive plant grows rapidly and then occupies a huge layer of freshwater bodies. Hence, challenges are facing many countries for implementing suitable approaches for the valorization of the world’s worst aquatic weed, and water hyacinth (WH). A critical and up-to-date review article has been conducted for more than 1 year, based on more than 100 scientific journal articles, case studies, and other scientific reports. Worldwide distribution of WH and the associated social, economic, and environmental impacts were described. In addition, an extensive evaluation of the most widely used and innovative valorization biotechnologies, leading to the production of biofertilizer and bioenergy from WH, and was dressed. Furthermore, an integrated search was used in order to examine the related advantages and drawbacks of each bioprocess, and future perspectives stated. Aerobic and anaerobic processes have their specific basic parameters, ensuring their standard performances. Composting was mostly used even at a large scale, for producing biofertilizers from WH. Nevertheless, this review explored some critical points to better optimize the conditions (presence of pollutants, inoculation, and duration) of composting. WH has a high potential for biofuel production, especially by implementing several pretreatment approaches. This review highlighted the combined pretreatment (physical-chemical-biological) as a promising approach to increase biofuel production. WH valorization must be in large quantities to tackle its fast proliferation and to ensure the generation of bio-based products with significant revenue. So, a road map for future researches and applications based on an advanced statistical study was conducted. Several recommendations were explored in terms of the choice of co-substrates, initial basic parameters, and pretreatment conditions and all crucial conditions for the production of biofuels from WH. These recommendations will be of a great interest to generate biofertilizers and bioenergy from WH, especially within the framework of a circular economy.

Noteworthy Bio Resource Utilization and Eco-Friendly Bioconversion Approaches of Versatile Invasive Aquatic Weed Water Hyacinth (Eichhornia Crassipes) Biomass - A Green Strategy for Aquatic Environmental Safety and Management of Aquatic Weeds.

Eichhornia crassipes (Water hyacinth) is considered as a hazardous weed in numerous places of the world. Despite of its harmful effects, the weed offers potential substrate for production of monetarily industrial important and value added products. In the present study, an eco-friendly bioconversion or biotransformation of processed water hyacinth biomass (WHB) into high efficiency fuel, adsorbent for brewery industry waste water treatment coupled methylene blue dye, biofertilizer and nutrient media for viable inoculam production of fungal biopesticide Nomuraea rileyi was carried out adopting green science in situ principles. Bioconversion of the WHB was initiated by alkali treatment which brought about notable differences in physical texture and chemical composition. Pre-treated WHB was enzymatically hydrolysed into soluble simple sugars followed by fermentation of the sugar into ethanol with 65.2 % total yield with 77.3 g/l final concentration. Batch studies reveals that WHB brought about effective reduction of various physicio chemical properties and notable adsorption efficacy. Plant growth promoting effect was studied using green gram (Vigna mungo). Green gram grew on soil under pot culture technique inoculated with WHB uncovers imperative plant growth promotion effect. Culture medium prepared from reconstituted WHB supported viable inoculum production of potential fungal biopesticide Beauveria bassiana. Fungal inoculum derived from the WHB based culture medium was effective against larval instars of castor semi-looper Achaea janata in terms of high mortality.The present examination uncovers the conceivable viable bioconversion of water hyacinth biomass (WHB) into different worth included vitality, ecological as gives a green procedure to cleaner production and the executives of aquatic invasive weeds.

Potential of Water Hyacinth (Eichhornia crassipes) as Compost and its Effect on Soil and Plant Properties: A Review

Water hyacinth, the devastating weed grows in water bodies either naturally or as a result of human interference, is considered as threat to environment due to its negative effects on aquatic ecosystems. To alleviate its negative impact utilization of those become as better mean in recent decades. As such, water hyacinth is known to has potential to be utilized as nutrient source via composting, all most all types of composting techniques are applicable in preparation of compost from water hyacinth. Being an organic source, water hyacinth helps build up soil organic matter, in turn play vital role in the enrichment of the soil physical, chemical and biological properties. Aggregation of soil particles, porosity, density, water holding capacity, nutrient availability, cation exchange capacity, pH, soil microorganism are the soil properties reported to improve with water hyacinth compost application. Moreover, water hyacinth compost seems to be far better than the animal manures in improvement of soil properties. As a result, water hyacinth compost shows magnificent effect of plant agronomic growth parameters such as germination percentage, number of leaves, leaf area index, plant height, length of shoot and root, root: shoot ratio, biomass content as well as yield parameters. However, utilization of water hyacinth has few challenges like difficulties in harvesting, chance for heavy metal accumulation, hardness during decomposition, less awareness. Properly managed water hyacinth compost would serve as an alternative for inorganic nutrient sources in future thus indirectly the threat caused by this aquatic weed on environmental would become minimum.

Evaluation of the Chemical Compounds and Antioxidant and Antimicrobial Activities of the Leaves of Eichhornia Crassipes (Water Hyacinth)

Background: Water hyacinth (WH) is an aquatic weed and one of the most productive plants on earth, causing serious environmental problems. Herein, some nutritional and phytochemical constituents of WH were investigated. Methods: Chemical analysis of Eichhornia Crassipes was carried out to determine total ash, humidity, crude protein, fat, fiber, and carbohydrate contents. Total phenolic and total flavonoid contents of the hydro-methanolic and aqueous extracts of the plant were determined using the Folin Ciocalteu and aluminum chloride colorimetric methods, and HPLC was performed to quantify eight phenolic compounds. The antioxidant and antimicrobial activities of the extracts were also evaluated. Results: The dry matter, total ash, crude protein, crude fiber, nitrogen-free extract, and ether extract contents of WH constituted 9.4, 12.9, 24, 11.5, 49.9, and 1.7%, respectively. The total phenolic contents of the hydro-methanolic and aqueous extracts were 491.2 ± 31.9 and 258.3 ± 10.8 mg gallic acid equivalents/g of dried extract, respectively. The total flavonoid content of the hydro-methanolic extract (76.8 ± 7.8) was higher than that of the aqueous extract (46.1 ± 6). Ferulic acid was found to be the most abundant phenolic compound in both extracts. The antioxidant activities of the hydro-methanolic and aqueous extracts were determined to be 221.52 and 97.07 mg ascorbic acid equivalent/g dry weight, respectively. The aqueous and hydro-methanolic extracts showed the highest antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, respectively. Conclusions: In conclusion, the present study indicated the applicability of WH as a natural source of antioxidants and antimicrobial agents.

The biological control of Egeria densa Planch. (Hydrocharitaceae) in South Africa

Over the last thirty years, biological control, the use of host-specific natural enemies, has been a huge asset in the management exotic aquatic macrophytes such as Pistia stratiotes L. (Araceae), Pontederia crassipes Mart. (Solms) (Pontederiaceae), Azolla filiculoides Lam. (Azollaceae), Salvinia molesta D.S. Mitch (Salviniaceae) and Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae), also known as the “Big Bad Five” in South Africa. Despite these successes, freshwater ecosystems in South Africa have been harder to restore to an invasive macrophyte-free space, due to chronic disturbances such eutrophication, propagule dispersal and hydrological alterations. In the Anthropocene, where human activities have profound effects on their environment, these disturbances weakens ecological resilience and drive aquatic plant invasions. Due to long periods of invasions and the presence of a new suite of exotic aquatic plant propagules, native vegetation recolonization has been slow or even absent. Instead, the release of resources, such as sunlight, nutrient and space through aquatic weed management acts as a catalyst for secondary biological invasion. New invasive aquatic weeds include submerged and rooted emergent growth types, with Egeria densa Planch. (Hydrocharitaceae) the most widely distributed submerged aquatic weed in South Africa. It can quickly form dense monoculture stands that have ecological, economic and social impacts. Because of its ability to regenerate from plant fragments with double nodes, mechanical control is inappropriate. Additionally, mechanical and chemical control not only affects E. densa but have significant non-target effects. In response to its rapid spread over the last 20 years, especially following floating invasive aquatic management, a biological control programme was initiated, and in 2018, the leaf-mining fly, Hydrellia egeriae Rodrigues (Diptera: Ephydridae) was released. This was the first release of a biological control agent against E. densa in the world, and the first agent released against a submerged aquatic weed in South Africa. This thesis comprises the subsequent step of a biological control program when permission for the release of an agent have been obtained. A brief history of macrophyte invasions in South Africa’s unique freshwater systems are given in the literature review. Contributing factors to secondary invasions within the context of ecological resilience are introduced. An argument for the benefit of biological control as nuisance control is given, especially because E. densa and its natural enemy, H. egeriae is the focus species of this thesis. The main goal after permission for the release of an agent have been obtained, is to establish and build-up field populations. Research questions in this thesis aimed to investigate factors that contribute to or negate this goal. Through laboratory and field experiments we investigated the thermal physiology of the agent, and its climatic suitability to its novel range; different release strategies on field establishment and biotic resistance through the acquisition of novel parasitoids. Considering the longevity of this biological control program, we investigated the effects of elevated CO2 on the interaction between E. densa and H. egeriae through open top chamber experiments. Laboratory thermal physiology results showed that the agent is able to survive, develop and proliferate at all E. densa sites throughout the year. This is confirmed with the establishment of the agent at two release sites, the Nahoon River in the Eastern Cape Province and the Midmar Dam in KwaZulu-Natal. Post-release surveys showed that H. egeriae requires augmentative releases to sustain field populations. Without augmentative releases, H. egeriae herbivory levels were almost negligent. However, a contributing factor to low field-populations was parasitism. The biological control agent acquired three parasitoids, which have previously been described from Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a specific herbivore to Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae). These results provide information on the immediate establishment and effectiveness of the H. egeriae. Results from the elevated CO2 study suggest that E. densa will become less nutritious through a shift in leaf C/N ratio, when ambient 800ppm is bubbled into experimental growth chambers. Hydrellia egeriae feeding was affected by ambient CO2 levels and plant nutrient availability. The set levels of ambient CO2 levels used in this experiment produced dissolved inorganic carbon levels that were lower than dissolved inorganic carbon levels in E. densa invaded sites. This suggests that, submerged aquatic plant-insect interactions may be harder to predict from only laboratory experiments. Further investigations are necessary to establish system-specific characteristics i.e. dissolved inorganic carbon and target plant nutritional quality. The biological control of E. densa in South Africa is still in its infancy. This study presents results from post-release surveys up until two years after the agent was released. From this study, Hydrellia egeriae exhibits the potential to be an effective biological control agent, but release strategies should be adapted to sustain field populations and to limit field parasitism effects. Continued post-release surveys will provide a more comprehensive idea of the seasonal fluctuations of field-populations and parasitism. Surveys at multiple sites will provide information on potential site specific characteristics that contribute to or negate biological effort. Considering the high nutrient status of South African freshwater systems, a more holistic approach to E. densa management is necessary. This will require the strengthening of ecological resilience to prevent systems from shifting into an alternate invasive stable state. In addition, aquatic weed management needs to be addressed by a resilient social network, which ultimately calls for the strengthening of socio-ecological resilience.

Valorization of Aquatic Weed and Agricultural Residues for Innovative Biopolymer Production and Their Biodegradation

In this work, water hyacinths, bagasse and rice straw were valorized to produce an innovative biopolymer. Serial steps of extraction, bleaching and conversion of cellulose to be carboxymethylcellulose (CMC) as well as the last steps of blending and molding were performed. The CMC was mixed with tapioca starch solution by a ratio of 9:18, and a plastic sizer of glycerol was varied at 2%, 4% and 6% by volume. In addition, bioplastic sheets were further determined in their properties and biodegradation. The results revealed that bioplastics with 6% glycerol showed a high moisture content of 23% and water solubility was increased by about 47.94% over 24 h. The effect of temperature on bioplastic stability was found in the ranges of 146.28–169.25 °C. Furthermore, bioplastic sheets with 2% glycerol could maintain their shape. Moreover, for texture analysis, the highest elastic texture in the range of 33.74–38.68% with 6% glycerol was used. Moreover, bioplastics were then tested for their biodegradation by landfill method. Under natural conditions, they degraded at about 10.75% by weight over 24 h after burying in 10 cm soil depth. After 144 h, bioplastics were completely decomposed. Successfully, the application of water, weed and agricultural wastes as raw materials to produce innovative bioplastic showed maximum benefits for an environmentally friendly product, which could also be a guideline for an alternative to replace synthetic plastics derived from petroleum.

Photodegradation Behaviour of Nitrogen-Containing Graphene Derivatives Towards Pollutant Dyes and Real-TimeAssessment on Aquatic Weed

Discharge of dyes in the aquatic system is ubiquitous environmental chaos, and combating this particular anthropogenic issue with graphene-based materials via photodegradation process has been a radiant approach in recent times. In this work, 3-aminophenol produced nanosheets of N-graphene (NG) in the presence of urea in a single step at a relatively low temperature of ~ 120 – 125°C in contrast to nitrogen-containing graphene oxide (NGO) produced in the absence of urea. The V- shape of urea facilitated the formation of a poly-hexagonal array of rings and prevented the attack of oxygen at normal atmospheric conditions. During the comparison of the photodegradation ability of both NG and NGO against MG, MB, and MO, the degradation efficiency was found to be 92 - 99%. Further LC-MS/MS studies proved that NGO was capable of mineralizing the complex structures of the dyes via the demethylation route initially followed by asymmetric cleaving at neutral pH. The in-vitro real-time application of an aquatic weed (Lemna minor) was also compared against the 1:1:1 ratio of MG, MB, MO, and NGO-treated dye water. No substantial growth of Lemna minor was found in the case of using the dye mixture even up to the 20th day, whereas rapid growth of this aquatic weed was observed within 15 days in the case of NGO treated dye mixture.