A review on energy and cost effective phase separated pretreatment of biosolids

Extracellular Polymeric Substances (EPS) existent in anaerobic sludge proves to be a barrier for sludge liquefaction and biomass lysis efficiency. Hence EPS deaggregation heightens the surface area for the subsequent pretreatment thereby uplifting the sludge disintegration and biomethanation rate. This review documents the role of EPS and its components which inhibits sludge hydrolysis and also the various phase separated pretreatment methods available with its disintegration mechanism to enhance the biomass lysis and methane production rate. It also illustrates the effects of phase separated pretreatment on the sludge disintegration rate which embodies two phases-floc disruption and cell lysis accompanied by their computation through biomethane potential assay and fermentation analysis comprehensively. Additionally, energy balance study and cost analysis requisite for successful implementation of a proposed phase separated pretreatment on a pilot scale level and their challenges are also reviewed. Overall this paper documents the potency of phase separated pretreatment for full scale approach.publishedVersio

Yukesh Kannah R

National Institute of Technology TiruchirappalliFaculty of Civil EngineeringTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

A review on energy and cost effective phase separated pretreatment of biosolids

Extracellular Polymeric Substances (EPS) existent in anaerobic sludge proves to be a barrier for sludge liquefaction and biomass lysis efficiency. Hence EPS deaggregation heightens the surface area for the subsequent pretreatment thereby uplifting the sludge disintegration and biomethanation rate. This review documents the role of EPS and its components which inhibits sludge hydrolysis and also the various phase separated pretreatment methods available with its disintegration mechanism to enhance the biomass lysis and methane production rate. It also illustrates the effects of phase separated pretreatment on the sludge disintegration rate which embodies two phases-floc disruption and cell lysis accompanied by their computation through biomethane potential assay and fermentation analysis comprehensively. Additionally, energy balance study and cost analysis requisite for successful implementation of a proposed phase separated pretreatment on a pilot scale level and their challenges are also reviewed. Overall this paper documents the potency of phase separated pretreatment for full scale approach

Recent insight into anaerobic digestion of lignocellulosic biomass for cost effective bioenergy generation

The progress of clean alternative energy sources is of very essential owing to the increase in an energy crisis and the escalating problems of climatic change. In this regard, bioenergy generation from carbohydrate-rich Lignocellulose biomass (LCB) is a promising technique, owing to its benefits such as ease of availability, decrease in harmful emissions, eco-friendly, energy efficiency and sustainability. The key constituents present in LCB are cellulose, hemicellulose, and lignin. This biological conversion of LCB faces difficulties due to the recalcitrance of lignin. Thus, the delignification of LCB is essential for the removal of complex lignin compounds. The primary technologies employed for the conversion of LCB biomass to bioenergy and pretreatment technologies involved in removing the lignin barrier have been extensively discussed in the present review. Different microorganisms and enzymes used for the delignification and detoxification process have also been studied for the scaling up of industrial bioenergy production from LCB

Food waste valorization by microalgae

In early twenty-first century, both developed and developing countries aim to avoid burning of fossil fuel in an effort to reduce the greenhouse gas emissions and impacts on global warming. Microalgae are potential key players for tackling greenhouse gas emissions and for providing feedstock for renewable energy production. Microalgae utilize freely available solar radiation as an energy source to extract protons and electrons from water to ultimately convert atmospheric carbon dioxide into organic carbon manifested in the growth rates and biomass concentrations. The microalgal biomass consists of biopolymers (protein and carbohydrate), lipid and pigments, which provides a platform for producing value-added products or for utilization as renewable energy resources. However, carbon and nutrient requirements for their cultivation are major bottlenecks adding to the overall production costs. Alternatively, food waste could be used for cultivation of microalgae after suitable pretreatment to solubilize organic carbon polymers. In an integrated bio-refinery approach, harvested microalgal biomass, value-added products are extracted sequentially, with the leftover components (those that do not have a significant market value) to be used in energy generation through anaerobic digestion/fermentation processes. This chapter will provide an overview on food waste valorisation by and most suitable species of microalgae, a brief discussion on adopting various pretreatment techniques for solubilization of carbon from food waste for easy valorisation by microalgae

Dispersion induced ozone pretreatment of waste activated biosolids: arriving biomethanation modelling parameters, energetic and cost assessment

In this study, the phase separated effect of dispersion induced ozone pretreatment (DOP) was investigated. Solid reduction, biomass lysis and biomethane production were used as essential parameters to assess the potential of DOP over ozone pretreatment (OP). A higher suspended solid reduction of about 25.2% was achieved in DOP than OP 18%. The ozone dosage of 0.014 gO 3 /g SS supported a maximal biomass lysis of about 32.8% when the biosolids were subjected to prior dispersion at 30 s and 3000 rpm. However, the same ozone dosage without phase separation achieved 9.6% biomass lysis. The second exponential model results of the biomethane assay showed that DOP enhanced the accessibility of disintegrated biosolids for methane production and induced about 1150 mL/g VS of methane production. The energy analysis reveals that DOP provides significant amount of positive net energy (152.65 kWh/ton) when compared to OP (−12.42 kWh/ton)

Effect of Dispersion Treatment on Dairy Waste Activated Sludge to Hasten the Production of Biogas

The solubilization potential of biological pre-treatment for waste activated sludge (WAS) is limited due to the floc structure of the WAS. Extra polymeric substances (EPS) are responsible for floc formation. In this investigation, an attempt has been made to disturb the floc structure of WAS by removing EPS with a disperser. In the first stage, the disperser treatment released 242 mg/L of soluble EPS when operated at 3,000 rpm for a duration of 50 s and caused deflocculation of WAS. In the second stage, deflocculated sludge was subjected to bacterial pre-treatment to assess the effect of floc disruption. During bacterial pre-treatment, it was found that deflocculated sludge produced higher organic solubilization of 23.9% and a reduction in suspended solids of 19.1% when compared to control (10.2 and 8.7%, respectively). Biogas yields were recorded of 220 mL/g COD in deflocculated sludge and 93 mL/g COD in flocculated sludge. From the above, it is evident that deflocculation effectively enhanced bacterial pre-treatment, leading to more solubilization and biogas production.publishedVersio

Polyhydroxyalkanoates synthesis using acidogenic fermentative effluents

Polyhydroxyalkanoates (PHA) are natural polyesters synthesized by microbes which consume excess amount of carbon and less amount of nutrients. It is biodegradable in nature, and it synthesized from renewable resources. It is considered as a future polymer, which act as an attractive replacement to petrochemical based polymers. The main hindrance to the commercial application of PHA is the high manufacturing cost. This article provides an overview of different cost-effective substrates, their characteristics and composition, major strains involved in economical production of PHA and biosynthetic pathways leading to accumulation of PHA. This review also covers the operational parameters, various fermentative modes including batch, fed-batch, repeated fed-batch and continuous fed-batch systems, along with advanced feeding strategies such as single pulse carbon feeding, feed forward control, intermittent carbon feeding, feast famine conditions to observe their effects for improving PHA synthesis and associated challenges. In addition, it also presents the economic analysis and future perspectives for the commercialization of PHA production process thereby making the process sustainable and lucrative with the possibility of commercial biomanufacturing