S. M. Tauseef

A Brief History of Anaerobic Digestion and “Biogas”

This chapter briefly traces the history of anaerobic digestion from the time the existence of this phenomenon was first recorded four centuries ago to its rapidly increasing popularity at present. The extent of adaptation of biogas technology across the world is also briefly reviewed. Whereas China and India lead the initiative from among developing countries, the thrust of the developed world is mainly coming from Western Europe.

Control of amphibious weed ipomoea (Ipomoea carnea) by utilizing it for the extraction of volatile fatty acids as energy precursors

Volatile fatty acids (VFAs), comprising mainly of acetic acid and lesser quantities of propionic and butyric acids, are generated when zoomass or phytomass is acted upon by acidogenic and acetogenic microorganisms. VFAs can be utilized by methanogens under anaerobic conditions to generate flammable methane–carbon dioxide mixtures known as ‘biogas’. Acting on the premise that this manner of VFA utilization for generating relatively clean energy can be easily accomplished in a controlled fashion in conventional biogas plants as well as higher-rate anaerobic digesters, we have carried out studies aimed to generate VFAs from the pernicious weed ipomoea (Ipomoea carnea). The VFA extraction was accomplished by a simple yet effective technology, appropriate for use even by laypersons. For this acid-phase reactors were set, to which measured quantities of ipomoea leaves were charged along with water inoculated with cow dung. The reactors were stirred intermittently. It was found that VFA production started within hours of the mixing of the reactants and peaked by the 10th or 11th day in all the reactors, effecting a conversion of over 10% of the biomass into VFAs. The reactor performance had good reproducibility and the process appeared easily controllable, frugal and robust.

Biogas and Biogas Energy: An Introduction

“Biogas” is the name popularly used to denote the flammable mixture of gases that are generated when organic material undergoes anaerobic decomposition. The mixture contains 40–70% (usually 55–65%) methane, carbon dioxide, and traces of other gases. “Biogas” has good calorific value and can be directly used as fuel or indirectly used to generate electricity.

Conversion of Volatile Fatty Acids (VFAs) Obtained from Ipomoea (Ipomoea carnea) to Energy

As the sequel to the work reported in Chapter 18, we describe conversion of volatile fatty acids (VFAs), obtained from ipomoea (Ipomoea carnea), into energy in the form of biogas employing upflow anaerobic sludge blanket (UASB) reactors.

Risk of Fuel Spills and the Transient Models of Spill Area Forecasting

Most accidents in chemical process industry, as well as a large number of fires in general, are triggered by accidental spilling of flammable liquids. Such spills either get auto-ignited or are set on fire by one or the other ignition source. If other flammable material happens to catch fire before the initial fire is extinguished, the accident gets escalated. In many situations, the escalation is catastrophic, resulting in very large fires, with or without explosions. This paper assesses the transient models developed so far to predict the areas covered by accidental fuel spills.

Biogas and Global Warming

The virtues of biogas as a clean fuel have been known since the late nineteenth century but the great resurgence of interest in biogas capture – hence methane capture – is due to the rapidly growing spectre of global warming (GW). Anthropogenic causes, which directly or indirectly release methane into the atmosphere, are responsible for as much as a third of the overall additional GW that is occurring at present. Hence the dual advantage of methane capture – generating energy while controlling GW – have come to the fore.

Biogas Capture from Wastewaters: The High-Rate Anaerobic Digesters

Starting with the introduction of anaerobic filter in 1967, a string of breakthroughs in anaerobic reactor design occurred during the late 1960s and early 1970s. These breakthroughs made it possible to extend the reach of anaerobic digestion from highly concentrated (in volatile organics content) manure slurry or sewage-sludge to much less concentrated industrial wastewaters. Later the reach was further extended to dilute wastewaters like domestic sewage and wash-waters.

Biogas Capture from Animal Manure

Prior to the 1970s, the principle use of anaerobic digestion across the world was in manure management. Whereas developing countries – principally India and China – used “biogas technology” to extract fuel from manure, developed countries used anaerobic digestion mainly to stabilize the manure, with little concern for the methane that was generated in the bargain.

Use of the terrestrial weed Alternanthera ficoidea in treating greywater in soil-less SHEFROL® bioreactors

The ornamental plant Alternanthera ficoidea (also named A. tenella), which is common and widespread throughout the tropics and is being increasingly regarded as an invasive, problematic weed, has been explored as a bioagent in greywater treatment. In the recently developed SHEFROL® bioreactor, it was seen to treat greywater of varying strengths (250-1,300 mg/L chemical oxygen demand, COD) quickly and substantially to the extent of 75-77%. Biological oxygen demand (BOD), nitrogen, phosphorus, suspended solids, and heavy metals copper, nickel, manganese, and zinc were also removed to the extents of 83.5, 94.9, 33.1, 27.0, 44.8, 27.5, 38.2, and 43.2%, respectively. As all this was achieved in a single pot, single step, and in a simple reactor operation, at hydraulic retention times of a mere 6 h, it shows the process to be several times more efficient as well as potentially less expensive than the conventional treatment systems which utilize macrophytes in tanks or constructed wetlands.

Need for Better High-Rise Building Evacuation Practices

There are various egress components for high-rise building evacuation during an emergency. It is recommended to use these components depending on the type of scenario, but it is important to note that there are certain advantages and disadvantages associated with these egress components. The concept of deciding suitable fire safety system of the building, i.e., available safe evacuation time (ASET) and required safe evacuation time (RSET) is very important while deciding their use. Apart from these egress components, there are few important evacuation strategies which can be used during building evacuation. To study different characteristics of evacuation of the building using various egress components, few computerized fire models are available, but we need further better evacuation strategies, considering the limitations associated with these egress components.