Sequential valorization strategies for dairy wastewater and water hyacinth to produce fuel and fertilizer

Abstract

To overcome the obstacles of treatment of dairy wastewater (DW) under anaerobic mono‐digestion and sustainable disposal of harvested water hyacinth (WH) a novel sequential valorization strategy was adopted to obtain fuel and fertilizer. Initially, DW and WH were subjected for anaerobic co‐digestion to elucidate the synergistic effect of the substrates to improve the process efficiency and increased biomethane production. The results indicated that the co‐digestion mixture (DW: WH‐1:1) has resulted in biomethane yield of 504.38 L/Kg VSfed which is 1.28‐fold and 3.14‐fold higher as compared to the mono‐digestion of WH (431.71 L/Kg VSfed) and DW (160.59 L/Kg VSfed), respectively. Further, the residual digestate was subjected for slow pyrolysis (320 ± 15°C) to obtain bio‐oil and biochar. The obtained bio‐oil shown superior fuel characteristics as compared to direct WH bio‐oil resulting in density, viscosity, and calorific value of 1.21 ± 0.04 g/ml, 1.8 ± 0.05 cSt and 1766.82 ± 11.53 KJ/Kg, respectively. The biochar residue from pyrolysis was amended to the soil to determine its bio‐fertilizing property. The soil properties in terms of bulk density, porosity, organic carbon, and pH were enhanced. Tomato cultivation in biochar amended soil shown comparable vegetative growth to that of digestate and urea thereby advocating the replacement of chemical fertilizers. Practical Application With recent increase in environmental concerns and requirement to meet the prescribed limits for effluent discharge from the industries, especially from food processing for the protection of aquatic bodies, there is a requirement of adoption of cost effective technology that could provide both economic and ecological sustainability. In this study, a sequential valorization strategy was adopted for efficient management of dairy wastewater and harvested water hyacinth from the water resources. The resultant products biogas, bio‐oil and biochar could be potentially used as fuel and fertilizer. Circular bio‐economy is in need of time which could be attainable by the implementation of such strategies in large scale industries for efficient waste management and resource recovery. This will not only benefit the environment but also to the society by galvanizing the sustainable development technology.

Bioprocessing of fermentable sugars derived from water hyacinth into microbial lipids and single cell proteins by oleaginous yeast Rhodosporidium toruloides NCIM 3547

“…6%, w/w) and volatile solid content (97.3%, w/w) of WH indicates that the structural components cellulose and hemicellulose are highly available as raw materials for biorefinery and bio-based conversion routes. As reported, based on the season of harvest, geographical location and the plant cell wall maturity, the relative composition of the structural and elemental characteristics of WH in this present study varies slightly with the previous studies [24,25,45,46].…”

“…Widespread of this biomass on water surface has created numerous ecological problems like destruction of aquatic flora and fauna, irrigation problems as well as caused several vector borne diseases in humans [21,22]. Thus, the demand for eradication and valorization of WH has grown rapidly in recent years and resulted in its various applications like biomanure [22], bioethanol [18,23] and biogas production [24,25]. However, utilization of WH for yeast based lipid production has not been reported so far.…”

A Comprehensive Evaluation of the Existing Approaches for Controlling and Managing the Proliferation of Water Hyacinth (Eichhornia crassipes): Review

“…This study indicated the feasibility of sustainable valorization of WH-derived liquid hydrolysate towards a biorefinery framework Alankar et al (2021). By the way, Arutselvy et al (2020), have conducted a sequential valorization strategy for dairy wastewater (DW) and WH to produce fuel and fertilizer. Anaerobic co-digestion of WH and DW improved the process efficiency and increased biomethane production.…”

Circular Bio-economy—Paradigm for the Future: Systematic Review of Scientific Journal Publications from 2015 to 2021

“…Co-digestion of diverse bio-waste streams like harvested water hyacinth and dairy wastewater, tested by [69], also yielded a wide range of bio-products, quite like in [108]. Even the leachate from the organic fraction of municipal solid wastes (MSW)-be it from collection trucks or landfills-which is looked upon as nothing other than an environmental menace, can be the source of medium-chain fatty acids [109].…”