Search

This chapter discusses in brief technology development in various aspects of ecophysiology and biochemistry of trees such as morphology and anatomy, general ecophysiology, specific techniques, formation of growth rings,, growth, and assessment of productivity, miscellaneous techniques, chemical composition of wood, etc.

The aim of this study was to treat food waste containing 25% total solids (TS) through dry anaerobic digestion (dry AD) process at various pressures (0.5 to 2.5 kg/cm2) and different time duration (20 to 100 min) to understand the impact of pretreatment in enhancing the methane generation potential along with insights on scale up. The findings revealed that vs. reduction and methane yield of 60% and 0.25 L CH4/(g VSadded) can be achieved with pretreated food waste at two kilograms per square centimeter, while pretreatment of food waste at 2 kg/cm2 for 100 min enhanced the vs. reduction from 60% to 85% and methane yield from 0.25 to 0.368 L CH4/(g VSadded). However, the net energy indicated that 40 min of pre -treatment at two kilograms per square centimeter can be a suitable option as methane yield and vs. reduction of 0.272 L CH4/(g VSadded) and 70%, respectively was achieved. The vs. reduction and the methane yield of 45% and 0.14 L CH4/(g VSadded), respectively was obtained from untreated food waste which illustrated that pretreatment had significantly impacted on the enhancement of methane generation and organic matter removal which can make the dry AD process more attractive and feasible at commercial scale.

Fiber to yarn conversion process in cotton has been affected by several factors which include harvesting methods, postharvest technology, and other factors affecting fiber quality. The fiber quality of cotton can be improved by different breeding techniques. Research work on harvest methods and improvement of fiber quality is being done through various approaches and many advancements have been made that need to be assembled together. Therefore, in this chapter, recent approaches and their efficiency are being presented. A brief review of recent researches is given to introduce the current state of the research on harvesting methods and on improving fiber quality which can be reconsidered in novel ways.

Bangladesh is a riverine country. Every year it faces many natural hazards due to river. Bangladesh is mainly formed by alluvial deposits. It faces riverbank erosion frequently due to regular shifting of river channels. This research work provides an overview of the trend of riverbank erosion of Padma River of Munshiganj, Madaripur and Shariatpur district. It also shows the land cover change due to riverbank erosion. The riverbank erosion was calculated by using remote sensing and geographic information systems (GIS) techniques. Only secondary data have been used to reach the research goals. Various computer software such as Erdas Imagine, Arc GIS, Google Earth, Environment for Visualizing Images etc. have been used to process and analyze raw data. In this study, using seven selected images of Landsat TM and OLI acquired from 1988 to 2017, the riverbank migration patterns and land dynamics of Padma resulted from accretion/erosion processes for 29 years were investigated. The migration rates are based on the differences in 1988–1993, 1993–1998, 1998–2003, 2003–2008, 2008–2013 and 2013–2017. The average erosion and accretion rates are 1472.056 and 1610.152 ha/year of Padma, respectively. This study shows Padma got meandered and braided from almost straight channel in the time span.

Food waste (FW) and sewage sludge (SS) were anaerobically co digested under solid state conditions (Total solids >15%) and observed that mixing ratio of 3:1 and 2:1 is optimum for mesophilic and thermophilic conditions respectively. The VS reduction and methane yield at optimized ratio was 76% and 0.35 L CH4/(g VS reduced) respectively at mesophilic temperature whereas it was 88% and 0.42 L CH4/(g VS reduced) at thermophilic temperature. The metagenomic analysis for these cases were done and high throughput DNA sequencing revealed that diversified bacterial groups that participate in the different metabolisms (hydrolysis, acidogenesis and acetogenesis) were mainly dominated by the phylum Firmicutes and Bacteriodetes. Genus Methanothrix is found to be dominant which is capable of generating methane by any methanogenic pathway among all the archaeal communities in the reactors followed by Methanolinea and Methanoculleus. However, it was understood through metagenomic studies that acetotrophic pathway is observed to be the major metabolic pathway in the reactors.

This study investigated the impact of the potential cellulose degrading bacteria that could be bioaugmented in the solid-state anaerobic digestion (SSAD) of bagasse to enhance the methane yield. The prospective anaerobic cellulose degrading bacteria was isolated from the soil. SSAD experiments were organized with & without bioaugmentation with a substrate total solid (TS) of 25%, 30%, 40% and 50% at an optimized feed to microorganism (F/M) ratio of 1:1. The maximum yield of 0.44 L CH4/ (g VS added) was obtained from bioaugmented bagasse at a TS of 40% whereas it was 0.34 L CH4/(g VS added) for non-bioaugmented bagasse. The isolated bacterial strain was identified that belongs species Pseudomonas of Gamma Proteobacteria which exhibited good cellulolytic activity. Metagenomic studies found 90% of archaeal microorganisms affiliated to Methanosaeta, a strict acetoclastic methanogen.

A massive challenge in handling and disposing the polymeric waste, generated by the growing human population and continuous development, has been faced currently as a result of human negligence. Fortunately, among many methods to deal with the problem of increasing polymer debris in the environment, pyrolysis stands out due to its efficiency and accessibility. In the present study, automobile plastic scrap (APS) and tyre crumb rubber (TCR) materials as a combination were subjected to co-pyrolysis using a novel catalyst (NOVC-FZP) that was synthesized using ferrocene and zeolite as precursors. Thermogravimetric analysis (TGA) of the raw materials (APS and TCR) shows single-stage decomposition at 402 °C and 340 °C, respectively. Gas chromatography-mass spectroscopy (GC-MS) analysis confirms higher production of the hydrocarbon (HC) groups in the oil with NOVC-FZP as compared to the neat oil (without NOVC-FZP). The cetane index of the oil with NOVC-FZP was found to be 22 and the calorific value of the same was 9162 Cal/g. A very high proportion of gasoline (86.8% of oil) was found in the oil resulting from the catalyzed pyrolysis. Solid product char (SPC) obtained through pyrolysis was incorporated into linear low-density polyethylene (LLDPE) to form LLDPE/SPC composite (LCC) for use in several applications rather than disposing it off. Higher mechanical properties like tensile strength, hardness as well as enhanced dielectric constant were exhibited by the prepared LCC.

Microorganisms are smart enough to evolve within the anaerobic ecosystems with tiny alteration in the process of fermentation as per the system dynamics. This study tries to elucidate the change in community structure of the consortia in anaerobic digestion of rice straw, bagasse, press mud, and vegetable waste with respect to its complexity. With the aid of metagenomic studies, it is found that Bacteroidetes and Firmicutes dominated the metabolic pathway for generation of precursors for methane production. The highest methane yield of 0.38 L CH4/(g VSadded) was obtained for rice straw followed by bagasse, press mud and vegetable waste. However, maximum VS reduction of 70% was observed for vegetable waste followed by rice straw (67%), baggase (60%) and press mud (60%). Acetoclastic methanogenesis is the dominating methane metabolic pathway with Methanosaeta dominating archaea in all the reactors.

High rate biomethanation technology based on anaerobic gas lift reactor (AGR) for the treatment of poultry litter (PL) has been demonstrated to generate biogas and digestate. The plant was installed and operated continuously for 95 weeks (September 2012 to June 2014) under ambient temperature conditions (in the range of 24–31 °C) for the treatment of 1000 kg of PL per day containing 254 kg of total solids and 220 kg of volatile solids. Biogas (68 m 3 /day) produced in the plant was successfully converted to electrical power (89 kWh/day) that was utilized to operate water pumps in the agricultural fields. The digestate (105 kg/day) was effectively employed in the nearby fields as an organic fertilizer. The plant was operated by establishing an intensified process mechanism incorporating inline pre and post processing unit assembly along with ammonia inhibition control mechanism. It is understood from the full scale experience of this plant that, decentralized off grid power generation from PL could be a remunerative option to poultry farmers.

The purpose of this study was to investigate the effect of pre-treatment and F/M (Food to Microorganism) ratios for the rapid generation of volatile fatty acids (VFA) from livestock organic wastes (cattle manure (CM) and poultry litter (PL)) through an anaerobic acidification process at a pH range of 4.5-5.5. Experiments were organized using CM and PL in batch reactors (1L and 25L) with and with no pre-treatment of substrate at F/M ratios (0.4, 0.6, 0.8 and 1). Among various existing pre-treatments methods, thermal-acidic (120°C; 1% H2SO4) pre-treatment was found effective. The results revealed that 0.31 and 0.47kg VFA/(kg VS reduced) could be obtained from CM and PL respectively with no pre-treatment, whereas it improvised to 0.43 and 0.67kg VFA/(kg VS reduced) correspondingly due to pre-treatment. Aforesaid, better yield of VFA was obtained at F/M ratio of 1.0, pH-5.5 and hydraulic residence time of 4days.

Landfill leachate (LL), which can contaminate both ground and surface water is a major global environmental issue. The aim of the present study was to investigate the biomethane potential (BMP) of a high-strength LL with low pH (5.0), high solids concentration (16%), and high organic matter (170 g/L of chemical oxygen demand (COD); 55 g/L of volatile fatty acids (VFA)) with ammonia nitrogen (NH3-N) (17 g/L). We investigated the BMP of LL at four different initial organic loadings (IOL) of 170 g/L, 85 g/L, 42.5 g/L and 21 g/L of COD and Food to inoculum (F/I) ratios of 0.5; 1; 2 and 3 at mesophilic (35 ± 2 °C) and thermophilic temperatures (55 ± 2 °C). We found that the highest cumulative CH4 could be obtained at an IOL of 42.5 g/L of COD regardless of the F/I ratio and temperature. The highest methane content results in biogas at an IOL of 42.5 g/L were 72% and 74% at mesophilic and thermophilic temperatures respectively. About 80–100% of cumulative methane was produced within 15 days in thermophilic reactors, and 40–72% in mesophilic reactors. The kinetic study revealed a fourfold reduction of lag phase in thermophilic compared to mesophilic reactors. The methane yield and organic matter removal rate increased as the concentration of IOL in LL decreased from 170 g/L to 21 g/L regardless of temperature. There exists an inverse correlation between IOL and organic matter removal efficiency. About 80% COD reduction was obtained at mesophilic temperature, and 90% at thermophilic temperature, at an IOL of 42.5 g/L and 21 g/L of COD. The modified Gompertz model showed a good fit to the experimental data, with R2 > 0.98 in all cases. Overall, the findings of this study conclude that treatment of acids rich and high-strength LL both at mesophilic and thermophilic temperature is feasible at an optimum IOL of 42.5 g/L of COD. However, treatment of LL at thermophilic temperature outperformed compared to mesophilic over the digestion time.

Increasing volume of Food waste (FW) and cardboard (CB) which are the two major fractions of municipal solid waste increases environmental concerns. This study evaluated the performance of a pilot-scale auto-fed continuous stirred tank reactor (CSTR) system for the solid-state anaerobic co-digestion (ACoD) of acetic acid rich food waste (FW) and cardboard (CB). The objective to co-digest acids rich FW and CB originates from the fact that acetic acid can act as a pre-treatment agent. Can the frequency of feeding and feeding pattern assists the system to withstand an organic loading rate >4 g volatile solids (VS)/(L.d) without addition of any pH boosting chemicals? Four mixing ratios of 100:0, 80:20, 60:40, 50:50 (v/v %) of FW and CB on biogas yield and process stability at an OLR > 4 g VS/(L.d) at a hydraulic residence time (HRT) of 40 d was investigated. Results revealed that the reactor R1 operated with FW:CB in the ratio of 100:0 achieved 76% biodegradability (the ratio of experimental to theoretical methane yield) while it was 39%, 32% and 22% for FW:CB ratios of 80:20, 60:40 and 50:50, respectively. This study concludes that exposing the CB to acetic acid-rich FW assisted the disintegration and depolymerization of CB without any pre-treatment step. Micro-feeding the reactor on an hourly basis assisted to overcome the susceptible failure of the system. The outcomes of this study provides new insight into the potential of implementing decentralized AD units for the treatment of FW and CB at source, which not only diverts waste from landfills but creates a revenue model through bioenergy generation and digestate sales.

The aim of the present work was to study and infer a full scale experience on co-digestion of 1000 kg of FW (400 kg cooked food waste and 600 kg uncooked food waste) and 2000 L of rice gruel (RG) on daily basis based on a high rate biomethanation technology called “Anaerobic gas lift reactor” (AGR). The pH of raw substrate was low (5.2–5.5) that resulted in rapid acidification phenomena with in 12 h in the feed preparation tank that facilitated to obtain a lower hydraulic residence time (HRT) of 10 days. At full load, AGR was fed with 245 kg of total solids, 205 kg of volatile solids (167 kg of organic matter in terms of chemical oxygen demand) which resulted in the generation of biogas and bio manure of 140 m 3 /day and 110 kg/day respectively. The produced biogas replaced 60–70 kg of LPG per day.

In the municipal solid waste, both cooked food waste (CFW) and uncooked food waste (UFW) are present, which need stabilization. In the proposed process, simultaneous generation of biogas, biomanure and a mixture of volatile fatty acids (VFA's) through anaerobic biorefinery approach were examined. The experimentations divulged that CFW having an average total solids (TS) and volatile solids (VS) in the range of 23% and 17%, yielded biogas of 0.47 m 3 /(kg VS reduced) and biomanure of 0.29 kg/(kg CFW) in single stage biomethanation process, whereas when the same waste was subjected to two stage process (acidogenic followed by methanogenic), it resulted in getting VFA's of 0.44 kg/(kg VS reduced), biogas of 0.18 m 3 /(kg VS reduced) and biomanure of 0.27 kg/(kg CFW). Similarly, UFW having average TS and VS in the range of 10% and 9%, yielded biogas of 0.38 m 3 /(kg VS reduced), biomanure of 0.13 kg/(kg UFW) and VFA's of 0.31 kg/(kg VS reduced), biogas of 0.14 m 3 /(kg of VS reduced), biomanure of 0.12 kg/(kg UFW) in single and two stage processes, respectively. The study disclosed that two stage process was preferred over single stage for obtaining VFA, biogas and biomanure that are known as value added products.

The aim of the present work is to investigate the impact of acetic acid assisted ultrasound pre-treatment of food waste (FW) and cardboard (CB) to overcome the barriers of substrate characteristics. Anaerobic co-digestion (ACoD) experiments were conducted with FW and CB in the mixing ratios of 100:0, 80:20, 60:40 and 50:50 at a food to inoculum (F/I) ratio of 1:1 and 1:2 to investigate its impact on biogas yield, volatile solids (VS) removal, solubilization of organic matter and the specific energy (SE) required. Results revealed that the biogas yield obtained from ultrasound pre-treated samples regardless of mixing ratio was higher at a F/I ratio of 1:2 compared to 1:1. The formation of bubbles, cavities and floc matrix significantly increased and the particle size decreased from 100 μm to 10 μm for FW:CB of 60:40 and 50:50 after pre-treatment. Ultrasound pre-treatment for 45 min was adequate for FW:CB of 100:0 and 80:20 while it was 60 min for 60:40 and 50:50 for increased sCOD between 37 % - 53 %. The VS removal efficiencies increased between 3–15 % from pre-treated samples compared to untreated. The CB mixing ratio is inversely related to SE while directly related to sCOD. Overall, during ACoD of FW and CB, the FW:CB of 80:20 gave a higher biogas yield of 471 mL/g VSadded followed by 60:40 and 50:50.

The present study was aimed to demonstrate a semi-commercial biomethanation plant based on anaerobic gas lift reactor (AGR) for the mono and co-digestion of organic fraction of municipal solid waste (OFMSW) and landfill leachate (LL) for 47 weeks. The reactors were commissioned at a volatile organic loading rate (VOLR) starting from 0.4 to 6.2 kg VS/(m3·day) to investigate the impact of VOLR on the organic matter removal rates, substrate utilization rate using Stover-Kincannon reaction kinetics, biogas yield and microbial diversity. 16s-metagenomic sequencing of the species present in the inoculum that was acclimatized with OFMSW, LL separately and in combination was also performed to identify the dominant microbial species in the mixed microbial consortia. Results revealed that the VS reduction in AGR 1, AGR 2 and AGR 3 at full load was 46%, 42% and 47% respectively with a corresponding biogas generation of 73.8 m3/day, 42 m3/day and 60.8 m3/day. The biodegradability in AGR 1 was between 73% and 81% whereas in AGR 2 and AGR 3, it was between 57% and 78% and 64% and 86% respectively. The operational strategy of digestate recirculation facilitated in the reduced usage of buffering chemicals which impacted on overall financials of the plant. The techno-economic analysis suggests that these kinds of biomethanation plants are remunerative.

The objective of the present study is to assess the impact of TS concentration, substrate mixing ratio (co digestion) and thermal pretreatment on biogas production, methane yield, VS reduction (%) and quality of biomanure through dry anaerobic digestion (DAD) of food waste (FW) and cattle manure (CM). Results divulged that the optimum methane yield and biomanure of 0.18 and 0.21 m3 CH4/(kg VS reduced) and 3.15 and 2.8 kg/kg waste was obtained from FW at TS of 25% and 30% at an HRT of 41 and 31 days respectively whereas it was 0.32 and 0.43 m3 CH4/(kg VS reduced) and 2.2 and 1.15 kg/kg waste from pretreated FW at an HRT of 16 and 20 days correspondingly. Improvement of methane from 62 to 81% was obtained due to thermal pretreatment. The highest nutrient recovery in terms of N, P, K was found to be 5.14, 2.6 and 3.2 respectively.

This work aims to evaluate the impact of pH and initial organic load (IOL) in terms of Chemical Oxygen Demand (COD) of landfill leachate for the production of value added products during single and two stage anaerobic digestion (AD). It was observed that at an optimal IOL of 48 g/L, acetic acid was dominant at pH 5.5 whereas it was butyric acid at pH of 5.5–6.0 and 10–11. The yield of Volatile Fatty Acids (VFA) was dependent on IOL and it was in the range of 0.26 to 0.36 g VFA/(g COD removed). Methane was also harvested during single and two stage AD and found that it was varying in the range of 0.21–0.34 L CH 4 /(g COD removed) and 0.2–0.32 L CH 4 /(g COD removed) respectively. An overall increase of 21% COD removal was noticed in two stage AD in comparison to single stage.