Preface

Agricultural waste, which includes both natural (organic) and non-natural wastes, is a general term used to describe waste produced on a farm through various farming activities. These activities can include but are not limited to dairy farming, horticulture, seed growing, livestock breeding, grazing land, market gardens, nursery plots, and even woodlands. Agricultural and food industry residues, refuse and wastes constitute a significant proportion of world wide agricultural productivity. It has variously been estimated that these wastes can account for over 30% of world wide agricultural productivity. The boundaries to accommodate agricultural waste derived from animal agriculture and farming activities are identified in this book. Examples will be provided of how animal agriculture and various practices adopted at farm-scale impact on the environment. When discharged to the environment, agricultural wastes can be both beneficial and detrimental to living matter and the book will therefore also address the pros and cons of waste derived from animal agriculture in today's environment. Given agricultural wastes are not restricted to a particular location, but rather are distributed widely, their effect on natural resources such as surface and ground waters, soil and crops, as well as human health, will also be addressed.

Chapter 1 - Agricultural waste, which includes both natural (organic) and non-natural wastes, is a general term used to describe waste produced on a farm through various farming activities. These activities can include but are not limited to dairy farming, horticulture, seed growing, livestock breeding, grazing land, market gardens, nursery plots, and even woodlands that are used as ancillary to the use of the land for other agricultural purposes. Given 'agricultural waste' encompasses such a broad class of biodegradable and non-biodegradable components, the focus of this chapter is first to identify and narrow down the boundaries to accommodate agricultural waste derived from animal agriculture and farming activities. Examples are provided of how animal agriculture and various practices adopted at farm-scale impact on the environment. When discharged to the environment, agricultural wastes can be both beneficial and detrimental to living matter, and the review therefore also addresses the pros and cons of waste derived from animal agriculture in today's environment. Given agricultural wastes are not restricted to a particular location, but rather are distributed widely, their effect on natural resources such as surface and ground waters, soil and crops, as well as human health, are addressed.

Chapter 2 - The animal sector of agriculture has undergone major changes in the last several decades: organizational changes within the industry to enhance economic efficiency have resulted in larger confined production facilities that often are geographically concentrated. These changes, in turn, have given rise to concerns over the management of animal wastes and potential impacts on environmental quality.

Federal environmental law does not regulate all agricultural activities, but certain large animal feeding operations (AFOs) where animals are housed and raised in confinement are subject to regulation. The issue of applicability of these laws to livestock and poultry operations — especially the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, the Superfund law) and the Emergency Planning and Community Right-to-Know Act (EPCRA) — has been controversial and recently has drawn congressional attention.

Both Superfund and EPCRA have reporting requirements that are triggered when specified quantities of certain substances are released to the environment. In addition, Superfund authorizes federal cleanup of releases of hazardous substances, pollutants, or contaminants and imposes strict liability for cleanup and injuries to natural resources from releases of hazardous substances.

Superfund and EPCRA include citizen suit provisions that have been used to sue poultry producers and swine operations for violations of those laws. In two cases, environmental advocates claimed that AFO operators had failed to report ammonia emissions, in violation of Superfund and EPCRA. In both cases, federal courts supported broad interpretation of key terms defining applicability of the laws' reporting requirements. Three other cases in federal courts, while not specifically dealing with reporting violations, also have attracted attention, in part because they have raised the question of whether animal wastes that contain phosphorus are hazardous substances that can create cleanup and natural resource damage liability under Superfund. Two of these latter cases were settled; the third, brought by the Oklahoma Attorney General against poultry operations in Arkansas, is pending.

These lawsuits testing the applicability of Superfund and EPCRA to poultry and livestock operations have led to congressional interest in these issues. In the 109th Congress, legislation was introduced that would have amended CERCLA to clarify that manure is not a hazardous substance, pollutant, or contaminant under that act and that the laws' notification requirements would not apply to releases of manure. Proponents argued that Congress did not intend that either of these laws apply to agriculture and that enforcement and regulatory mechanisms under other laws are adequate to address environmental releases from animal agriculture. Opponents responded that enacting an exemption would severely hamper the ability of government and citizens to know about and respond to releases of hazardous substances caused by an animal agriculture operation. Congress did not act on the legislation, but similar bills have been introduced in the 110th Congress (H.R. 1398 and S. 807).

Agricultural and food industry residues, refuse and wastes constitute a significant proportion of worldwide agricultural productivity. It has variously been estimated that these wastes can account for over 30% of worldwide agricultural productivity. These wastes include lignocellulosic materials, fruit, vegetables, root and tuber wastes, sugar industry wastes as well as animal/livestock and fisheries operations wastes. They represent valuable biomass and potential solutions to problems of animal nutrition and worldwide supply of protein and calories if appropriate technologies can be deployed for their valorization. Moreover, reutilization of these vast wastes should help to address growing global demands for environmentally sustainable methods of production and pollution control.

Various technologies are potentially available for the valorization of these wastes. In addition to conventional waste management processes, other processes that may be used for the reprocessing of wastes include solid substrate fermentation, ensiling and high solid or slurry processes. In particular, the use of slurry processes in the form of (Autothermal) Thermophilic Aerobic Digestion (ATAD or TAD) or liquid composting is gaining prominence in the reprocessing of a variety of agricultural wastes because of its potential advantages over conventional waste reprocessing technologies. These advantages include the capacity to achieve rapid, cost-effective waste stabilization and pasteurization and protein enrichment of wastes for animal feed use.

TAD is a low technology capable of self heating and is particularly suited for use with wastes being considered for upgrading and recycling as animal feed supplement, as is currently the case with a variety of agricultural wastes. It is particularly suited for wastes generated as slurries, at high temperature or other high COD wastes. Reprocessing of a variety of agricultural wastes by TAD has been shown to result in very significant protein accretion and effective conversion of mineral nitrogen supplement to high-value feed grade microbial/single-cell protein for use in animal nutrition. The application of this technology in reprocessing of wastes will need to take account of the peculiarities of individual wastes and the environment in which they are generated, reprocessed and used. The use of thermopiles in the process has significant safety benefits and may be optimized to enhance user confidence and acceptability.

Chapter 4 - Fly ash has a potential in agriculture and related applications. Physically, fly ash occurs as very fine particles, having an average diameter of <10 mm, low- to medium-bulk density, high surface area and very light texture. Chemically, the composition of fly ash varies depending on the quality of coal used and the operating conditions of the thermal power stations. On average, approximately 95 to 99% of fly ash consists of oxides of Si, Al, Fe and Ca, and about 0.5 to 3.5% consists of Na, P, K and S. The remainder of the ash is composed of trace elements. In fact, fly ash consists of practically all of the elements present in soil except organic carbon and nitrogen (Table 1). Thus, it was discovered that this material could be used as an additive or amendment material in agricultural applications.

In view of the above, some agencies, individuals, and institutes at various locations conducted some preliminary studies on the effect and feasibility of fly ash as an input material in agricultural applications. Some amount of experience was gained in the country and abroad regarding the effect of fly ash utilisation in agriculture and related applications.

Chapter 5 - Modern farming employs many chemicals to produce and preserve large quantities of high-quality food. Fertilizers, pesticides, cleaners and crop preservatives are the major categories that are now abundantly used in agriculture for increasing production. But each of these chemicals poses a hazard—most of the pesticides are degraded very slowly by atmospheric and biological factors, leading to the development of resistant strains of pests, contamination of the environment and food chain, thereby causing serious ecological imbalance. However, in many countries, a range of pesticides has been banned or withdrawn for health or environmental reasons, and their residues are still detected in various substances such as food grains, fodder, milk, etc. The majority of chemical insecticides consist of an active ingredient (the actual poison) and a variety of additives that improve efficacy of their application and action. All of these formulations degrade over time. The chemical byproducts that form as the pesticide deteriorates can be even more toxic than the original product.

Often stockpiles of pesticides are poorly stored and toxic chemicals leak into the environment, turning potentially fertile soil into hazardous waste. Once a pesticide enters soil, it spreads at a rate that depends on the type of soil and pesticide, moisture and organic matter content of the soil and other factors. A relatively small amount of spilled pesticide can, therefore, create a much larger volume of contaminated soil. The International Code of Conduct on the Distribution and Use of Pesticides states that packaging or repackaging of pesticides should be done only on licensed premises where staff is adequately protected against toxic hazards. Now, many agencies have come forward to prevent the contamination and accumulation of pesticides in the environment—for example, the issuing of the International Code of Conduct on the Distribution and Use of Pesticides by the United Nations Food and Agriculture Organization (FAO). In addition, the organization works to improve pesticide regulation and management in developing countries. In order to prevent accumulation of pesticides, the WHO works to raise awareness among regulatory authorities and helps to ensure that good regulatory and management systems for the health sector are in place. The United Nations Industrial Development Organization (UNIDO) is supporting cleaner and safer pesticide production with moves toward less hazardous products based on botanical or biological agents. Wider use of these products will result in reductions in the imported chemicals that contribute to obsolete pesticide stockpiles. The World Bank has established a binding safeguard policy on pest management that stipulates that its financed projects involving pest management follow an Integrated Pest Management (IPM) approach.

Chapter 6 - An attempt was made to convert the agricultural waste of rice husk (RH) into an adsorbent to remove the offensive odor released from livestock waste and compost. The ammonia gas adsorption of the RH carbonized at 400°C was much faster than those of several commercial deodorants as well as those of carbonized wood wastes. Acidic functional groups remaining at 400°C were useful to promote adsorption of basic ammonia gas. The actual compost was covered with or mixed with the RH carbonized at 400°C. The covering method reduced the concentration of ammonia gas emitted from the compost much faster than the mixing method, which was connected to volatilization of ammonia gas lighter than ambient air. Wetting the carbonized RH was also effective in reducing the ammonia gas concentration. An assorted feed to which was added the RH carbonized at 400°C at the level of 2 mass% was given to growing pigs. The addition of the carbonized RH reduced about 80% of the concentrations of hydrogen sulfide and mercaptans emitted from the pig dung. The removal of acidic gases of hydrogen sulfide and mercaptans was suggested to result from basic inorganic matter of K, Ca and P, which were intrinsically composed in RH. The testing results showed that the RH carbonized at 400°C was a promising material for removing the offensive odor produced by the livestock industry.

Chapter 7 - The alarming rate of population growth and a regular depletion in food production and food resources are important factors in the present dire need to find new viable options for food and feed sources. Based on scientific developments, particularly in industrial microbiology, one feasible solution could be the consumption of microorganisms as human food and animal feed supplements. Humans have used microbial-based products—like alcoholic beverages, curd, cheese, yogurt, and soya—even before the beginning of civilization. Due to research developments in the scientific arena in the last two decades, (Bio) single cell protein (SCP) has drawn new attention towards its use as supplement in human food, animal feed or staple diet. There are several benefits to using SCP as food or feed, viz. its rapid growth rate and high protein content. The microorganisms involved as SCP have the ability to utilize cheap and plentiful available feedstock for their growth and energy, making them an attractive option. However, in spite of laboratory-based success stories, only a limited number of commercial SCP production plants have been seen worldwide. This review analyzes the possibility of SCP production, various raw materials for its production, available microorganisms with cultivation methods, toxicity assessment and their removal. Also, new developments and risk assessment using SCP along with worldwide industrial SCP production are discussed.

Chapter 8 - The term "coffee" is applied to a wide range of coffee processing products, starting from the freshly harvested fruit (coffee cherries), to the separated green beans, to the product of consumption (ground roasted coffee or soluble coffee). Coffee processing can be divided into two major stages: primary processing, in which the coffee fruits are de-hulled and submitted to drying, the resulting product being the green coffee beans. This is the main product of international coffee trade, and Brazil is the largest producer in the world with production values ranging from 2 to 3 million tons in the years from 2003 to 2007. During this primary processing stage solid wastes are generated, which include coffee husks and pulps, and low-quality or defective coffee beans. Secondary processing includes the stages that comprise the production of roasted coffee and soluble coffee. The major solid residue generated in this stage corresponds to spent coffee grounds from soluble coffee production. These solid residues (coffee husks, defective coffee beans and spent coffee grounds) pose several problems in terms of adequate disposal, given the high amounts generated, environmental concerns and specific problems associated with each type of residue. Coffee husks, comprised of dry outer skin, pulp and parchment, are probably the major residues from the handling and processing of coffee, since for every kg of coffee beans produced, approximately 1 kg of husks are generated during dry processing. Defective beans correspond to over 50% of the coffee consumed in Brazil, being used by the roasting industries in blends with good-quality coffee. Unfortunately, since to coffee producers they represent an investment in growing, harvesting, and handling, they will continue to be dumped in the internal market in Brazil, unless alternative uses are sought and implemented. Spent coffee grounds are produced at a proportion of 1.5kg (25% moisture) for each kg of soluble coffee. This solid residue presents an additional disposal problem, given that it can be used for adulteration of roasted and ground coffee, being practically impossible to detect. In view of the aforementioned, the objective of the present study was to present a review of the works of research that have been developed in order to find alternative uses for coffee processing solid residues. Applications include direct use as fuel in farms, animal feed, fermentation studies, adsorption studies, biodiesel production and others. In conclusion, a discussion on the advantages and disadvantages of each proposed application is presented, together with suggestions for future studies and applications.

Chapter 9 - There are environmental concerns associated with industrial sludge disposal, apart from other issues like logistics of disposal, treatment options, cost of disposal, etc. A customary disposal option for many industries is secure landfilling, but more and more industries are now looking at the possibility of recycling and bioconversion of the solid wastes to value-added products. Agro-based industries have often resorted to composting, vermicomposting or biogas generation from their wastes due to their biological substrate value and negligible toxicity. However, this has not been the case with other types of industries like pharmaceuticals, chemicals/petrochemicals, power plants, iron and steel and many others, where the sludge is may be unsuitable due to the presence of harmful chemicals, volatiles, persistent organic pollutants (POPs), antibiotics, etc. Sludge generated from water treatment plants in the industrial sector forms a major portion of solid waste requiring disposal, and has been used in some reported cases for culturing earthworms and vermicomposting and could be explored for vermicomposting on case-by-case basis. An acceptable approach would be an initial evaluation of the sludge for screening of known harmful agents and factors to earthworms and then conducting proxy vermicomposting trials on these sludges with prior addition of known substrates of earthworms, such as cured animal manures or crop residues or a combination of both. The quality of the final product—or vermicompost—holds great importance, as the end product may not qualify as good manure. But, it is still not clear as to how one could solve the entire sludge disposal problem only by vermicomposting, as it is time-consuming and industries generate sizeable quantities of sludge every day. It appears that vermicomposting could only supplement the normal disposal practices of an industry. This chapter attempts to shortlist the suitable industrial and agricultural wastes for vermiconversion, explores the feasibility of their vermiconversion, and looks at various factors influencing the possible implementation of such a practice in industry.

Chapter 10 - While recycling of low added-value residual materials constitutes a present day challenge in many engineering branches, attention has been given to low-cost building materials with similar constructive features as those presented by materials traditionally employed in civil engineering. Bearing in mind their properties and performance, this chapter addresses prospective applications of some elected agroindustrial residues or by-products as non-conventional building materials as means to reduce dwelling costs.

Such is the case concerning blast furnace slag (BFS), a glassy granulated material regarded as a by-product from pig-iron manufacturing. Besides some form of activation, BFS requires grinding to fineness similar to commercial ordinary Portland cement (OPC) in order to be utilized as hydraulic binder. BFS hydration occurs very slowly at ambient temperatures while chemical or thermal activation (singly or in tandem) is required to promote acceptable dissolution rates. Fibrous wastes originated from sisal-banana agroindustry as well from eucalyptus cellulose pulp mills have been evaluated as raw materials for reinforcement of alternative cementitious matrices, based on ground BFS.

Production and appropriation of cellulose pulps from collected residues can considerably increase the reinforcement capacity by means of vegetable fibers. Composite preparation follows a conventional dough mixing method, ordinary vibration, and cure under saturated-air condition. Exposition of such components under ambient conditions leads to a significant long-term decay of mechanical properties while micro-structural analysis has identified degradation mechanisms of fibers as well as their petrifaction. Nevertheless, these materials can be used indoors and their physical and mechanical properties are discussed aiming at preparing panel products suitable for housing construction whereas results obtained thus far have pointed to their potential as low-cost construction materials.

On its turn, phosphogypsum rejected from phosphate fertilizer industries is another byproduct with little economic value up to now. Phosphogypsum may replace ordinary gypsum provided that radiological concerns about its handling have been properly overcome as it exhales 222Rn (a gaseous radionuclide whose indoor concentration should be limited and monitored). Some phosphogypsum properties of interest (e.g., bulk density, consistency, setting time, free and crystallization water content, and modulus of rupture) have suggested its large-scale exploitation as surrogate building material.

Chapter 11 - In a time when a foreseeable complete transmutation from a petroleum-based economy to a bio-based global economy finds itself in its early infancy, agricultural wastes, in the majority currently seen as low-valued materials, are already beginning their own transformation from high-volume waste disposal environmental problems to constituting natural resources for the production of a variety of eco-friendly and sustainable products, with second generation liquid biofuels being the leading ones. Agricultural wastes contain high levels of cellulose, hemicellulose, starch, proteins, and, some of them, also lipids, and as such constitute inexpensive candidates for the biotechnological production of liquid biofuels (e.g., bioethanol, biodiesel, dimethyl ether and dimethyl furan) without competing directly with the ever-growing need for world food supply. Since agricultural wastes are generated in large scales (in the range of billions of kilograms per year), thus being largely available and rather inexpensive, these materials have been considered potential sources for the production of biofuels for quite some time and have been thoroughly studied as such. In the last decades, a significant amount of information has been published on the potentiality of agricultural wastes to be suitably processed into biofuels, with bioethanol as the main research subject. Thus, it is the aim of this chapter to critically analyze the current situation and future needs for technological developments in the area of producing liquid biofuels from solid biowastes. The state-of-the-art in producing bioethanol, bio-oil and biodiesel from agricultural wastes will be discussed together with the new trends in the area. The emerging biowaste-based liquid biofuels (e.g., biogasoline, dimethyl ether and dimethyl furan) currently being studied will also be discussed.

In: Agricultural Wastes ISBN 978-1-60741-305-9

Eds: Geoffrey S. Ashworth and Pablo Azevedo © 2009 Nova Science Publishers, Inc.

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