In nature, nothing is considered as a WASTE— everything is Food for something else.
From creation, man was charged to ‘increase, multiply, and subdue the earth’. Thus, man has continually sought to improve the quality of life by transforming nature to provide more food, and better living conditions for long life. Agriculture and technology are part of the tools used to accomplish this transformation and to achieve many of man’s goals. Through mechanization and other tools of modern technology man cultivates crops and rears animals for his food needs, processes same through industrial activities for value addition, and carries out other sundry activities- all in a bid to dominate his environment.
Major fallout of all these is the generation of wastes, with their attendant implications for the environment generally. Generation of wastes demands that measures must be taken to manage them if the unpleasant consequences of their accumulation must be averted. Hence, various waste management options have been adopted over time, most of which had tended to see waste as useless entity that must be disposed off wholesomely. However, modern concepts of waste management tend to see waste from a different perspective, since what is regarded as waste may not be truly totally so, at least, from the point of view of salvageable resources entrapped therein. This is particularly so for agro-food wastes in which reasonable percentage of biomass form major part of what is often considered as wastes consigned to the waste bins. Fortunately, the entrapped resources are bioconvertible into useful products.
Wastes–Definition, Waste refers to anything considered useless, but produced by the same action that produces something useful. It could be a by-product of households, industrial, agricultural, municipal, mining, commercial, and sundry other ventures, activities or sources. However, the word waste may have different connotations, since what one considers waste may not be waste for another person. In other words, some wastes are not totally useless.
A major problem facing most developing nations of the world is to increase agricultural production without degrading the environment. Food is a basic human need and producing enough to feed the growing population of developing nations is one of the biggest challenges facing a large proportion of nations. Hence, there should be a greater intervention in form of
environment friendly science and technology in food production. One of such environment friendly intervention is effective management of wastes, particularly as it concerns agricultural and food processing wastes. The quality of the total environment and health status of the inhabitants are related to the quality and quantity of wastes generated in those areas, as partly defined by the nature of activities carried out by the populace. Agricultural activities produce many types of wastes in their daily operations such as biological waste, solid waste, hazardous waste, and waste water. It is important that these wastes are identified and managed properly to protect the dwellers in the community as well as the environment. Waste is directly linked to human development, both technologically and socially. The compositions of different wastes have varied over time and location, with anthropogenic activities, particularly industrial development and innovation, being directly linked to waste materials.
The food industry produces large volumes of wastes, both solids and liquids, resulting from the production, preparation and consumption of food. Currently, the transportation tools of food wastes is very simple and lacks seal, thus food wastes leak during storage, collection and transportation thereby polluting the environment. The surface water and groundwater can be polluted by waste leachate through surface runoff and osmosis. If food wastes are dumped randomly, they will occupy a lot of land space, emit unpleasant smell after decaying, producing large amounts of toxins and stench gas that pollute water and air. If poured into the sewers directly, it will cause the blockage of the sewer, affecting the city appearance and environmental sanitation seriously, and causing environmental pollution . Thus, these wastes pose increasing disposal and potentially severe pollution problems and represent a loss of valuable biomass and nutrients. Beside their pollution and hazard aspects, in many cases however, food processing wastes might have a potential for conversion into useful products of higher value as by-product, or even as raw material for other industries, or for use as food or feed after biological treatment.
Agricultural Waste Management Systems
An agricultural waste management system (AWMS) is a planned system in which all necessary components are installed and managed to control and use by-products of agricultural production in a manner that sustains or enhances the quality of air, water, soil, plant, animal, and energy resources.. Waste of different consistencies requires different management techniques and handling equipment. Agricultural waste may be in the form of a liquid, slurry, semisolid, or solid. Waste, such as manure, can change consistency throughout the system or throughout the year. The total solids (TS) concentration of manure is the main characteristic that indicates how the material can be handled. There has been technological advancement for processing, treatment and disposal of solid waste. Liquid waste management systems are often easier to automate and require less daily attention than those for solid wastes. However, the additional water needed increases the volume of waste requiring management, and the initial cost of the liquid handling equipment may be greater than that for solid waste systems.
Agricultural waste is collective term which is use for all the non economical substance produce by agricultural operations such as roots , crop residue ,live stock waste etc .
It is waste produced as a result of various agricultural operations (straw, bagasse, roots, peels etc.)
It includes manure and other wastes from farms, poultry houses and slaughter
houses, etc.
Agro-Food Processing Wastes: The Concept of Waste Minimization and
Recycling
The concept of waste as a material “which has no use” is changing to that of seeing waste as a resource by converting into secondary material with modification. Wastes can thus be converted into useful resources used at home or even sold for wealth. Waste recycling involves the collection of discarded materials such as husks, peels, poultry droppings, cow dung, biomass etc and processing these materials, and turning them into new products. As a matter of fact, recycling helps to turn waste into other usable forms. Waste recycling is synonymous with resource recovery. It is a process of turning what has been considered as waste into useful products. The essence of recycling is to minimize the quantities of waste exposed to our environment and the consequent health hazards.
FOOD PROCESSING WASTES AS VALUABLE RESOURCES FOR
INDUSTRIAL AND OMESTIC APPLICATIONS
Food processing wastes are those end products of various food processing industries that
have not been recycled or used for other purposes. Food processing industries release a large amount of waste materials because they process the crude raw materials (fruits, vegetables, animals, spices, condiments, cereals or pulses) into finished products. For example, the fruits and vegetable processing industries release 50% of the weight of raw materials as waste products in the form of peels, stones or fibres.
Agro-Food Wastes as Substrates for the Production of Different Types of
Enzymes
The utilization of agro-food residues for the production of enzymes via Solid State fermentation (SSF) has gained renewed interest as it solves solid waste disposal problem and also produce lesser waste water. Agricultural wastes present the most inexpensive and highly energy rich substrates for fermentation. In nature, solid organic substrates such as animal and plant residues, wood, crop residues, fruits, etc. Undergo complex microbial degradation and transformation by various microbiological processes. Agro-industrial residues are generally considered the best substrates for the Solid State fermentation (SSF) processes for the production of enzymes. A number of such substrates have been employed for the cultivation of microorganisms to produce lots of enzymes. The utilization of wastes such as wheat bran, molasses bran, maize meal, millet cereal, wheat flakes, barley bran, crushed maize, corncobs and crushed wheat have been exploited for the production of alpha amylase by thermophilic fungus Thermomyces lanuginosus under solid state fermentation.
Agro-Food Wastes as Substrates in Citric Acid and Propionic Acid Production
Citric acid is an important commercial product with a long list of applications in industrial sectors. It is used in the food, beverage, pharmaceutical, chemical, cosmetic and other industries for applications such as acidulation, chelation, emulsifiers, antioxidation, flavour enhancement, preservation, and plasticizer and as a synergistic agent. The food industry utilizes about 70% of the total production of citric acid, the pharmaceutical industry consumes 12% and the rest 18% has market for other applications. Its rising demand is subsequently causing an increase in global production. Currently citric acid is produced by fermentation-technology, using the filamentous fungus Aspergillus niger mainly through surface (solid or liquid) and submerged fermentation of starch or sucrose-based media. The filamentous fungus Aspergillus niger is the most commonly used microorganism for citric acid production.
Propionic acid (PA), on other hand, is widely used as additive in animal feed and also in the manufacturing of cellulose-based plastics, herbicides, and perfumes. Salts of propionic acid are used as preservative in food. PA is mainly produced by chemical synthesis. Nowadays, PA production by fermentation of low-cost industrial wastes or renewable sources has been an interesting alternative.
Agro-Food Wastes as Substrates for the Production of Microbial Biomass
(Single Cell Proteins)
Single cell proteins are the dried cells of microorganisms (such as yeast) that could be grown in large-scale culture systems for use as protein for human or animal consumption. Nowadays people are becoming health conscious and consume large quantities of fruits and fruit juices leading to the accumulation of fruit wastes. The disposal of wastes is a serious problem and their deposition poses health hazard to man and animals. These wastes can be used as a substrate for the growth of food fungi such as Aspergillus oryzae, Rhizopus oligosporus and several species of Agaricus and Morchella, the sources of protein, which may be utilized as a feed supplement for domestic animals and cattle and if found suitable for human consumption. Single cell protein production for feed use has been achieved by cultivation of organisms on ram horn hydrolysate, poultry process waste and acid hydrolysed shrimp waste.
Food Processing wastes As substrates for production of Animal Feeds
Various food processing industries produce a lot of wastes which can be of use in the production of animal feed. Cereals/grains milling factories generate a lot of wastes in the form of husks and chaff. These are further processed into animal feed for poultry. Groundnut cake is obtained from the groundnut processing industry during the production of groundnut oil. After extraction of the oil the resultant cake is taken up by formulators of animal feed for the production of poultry feed. Supplementation of animal feed with such waste increases the nutritional base of the feed. Groundnut cake is rich in proteins and other vital nutrients required by the birds for proper growth. Animal products processing industries also generate large amounts of bones after deboning of meats. The bones can be taken up, crushed and added to animal feeds to increase the calcium content of the feeds.
Wastes as Substrate for producing Food Additives
Pectin is a gelling agent. It creates bonds with water (pectin-water) and with itself (pectin- pectin).Pectin-pectin bond gives the gel the strength and pectin-water bond gives jelly its softness. A different proportion between those two types of bonds gives jam or jelly a different texture. Pectin is one of the most versatile stabilizers available. Pectin’s gelling, thickening and stabilizing attributes makes it an essential additive not only in jams and jellies
but also in the production of many other food products, as well as in pharmaceutical and medical applications. The citrus industry generates a lot of peels during the production of various types of citrus fruit juices. Such peels are now used for the production of pectins that are used as thickeners in such products as jams.
Wastes as substrates for the production of Aroma compounds & other important Industrial Chemicals
The world of aroma is very attractive especially because it concerns the taste of what we eat. Aroma compounds can be extracted from fruits or vegetables but as they are required in the product in concentrations comparable to those in the source material, and this utilizes high amounts of materials and is generally not economically realistic. Some residues like coffee pulp and husk, cassava bagasse, sugar cane bagasse are generated in large amounts during processing, and their disposal rather causes serious environmental problems. In recent years, there has been constant increase in the efforts to utilize these residues as substrates (carbon source) in bioprocessing, with microorganisms playing an important role in the generation of natural compounds, particularly in the field of food aromas.
Agro-Food Industrial Residues/Wastes as Substrates for Production of
Secondary Metabolites: Antibiotics, Steroids, Alkaloids, etc
Wastes produced annually can be used as a natural bioresource for the production of bioactive compounds such as secondary metabolites from various selected microorganisms. Secondary metabolites are excreted by microbial cultures at the end of primary growth and during the stationary phase of growth. Secondary metabolites represent some of the most economically important industrial products and are of huge interest. The best known and most extensively studied secondary metabolites are the antibiotics, steroids and alkaloids. Oxytetracycline, a broad-spectrum antibiotic, is a bacteriostatic antibiotic that inhibit protein
synthesis by binding reversibly to the 30S ribosomal subunit of the microorganism. It is therefore a very important class of antibiotics, and is used in human and veterinary medicine and as a supplement in poultry and swine production, preservation of fish, meat and poultry. It is also used in non-therapeutics for the control of plant diseases, stimulation of amino acid fermentation and inhibition of material biodeterioration . Several food processing wastes and by-products such as sweet potato residue, saw dust, rice hulls and corn cob, cassava peel, corn pomace, corncob, and groundnut shell and cocoyam peels have all served as effective substrates for the production of antibiotics by solid-state fermentation. Solid-state fermentation is defined as the process in which microbial growth and products formation occur on the surfaces of solid substrates in the near or absence of water.
.Wastes as Substrates for Paper Making
The utilization history of lignocellulose and fiber material has much to do with paper making industry which can date back to 3rd Century BC. Plant fiber is the raw material in the pulp and paper industry. Pulp and paper industry all focus on the utilization of the cellulose component in the fiber material and removal of both the hemi-cellulose and lignin components which accounts for the formation of black liquor. This process not only wastes the hemi-cellulose and lignin components, but the removal step dramatically generates the increment of the cost, and the black liquor pollutes the nearby environment especially the water resources.
Nutrient recycling from Organic Waste – Composting
After food wastes are degraded by aerobic microorganism, not only is the stench of the waste eliminated, but also the toxic and hazardous substances are degraded, the secondary pollution is avoided, and has good social and environmental benefits. The degradation products can be divided into organic fertilizer, bio-organic fertilizer and soil conditioner, which contain a variety of plant growth accelerating agent, and as application fertilizer can be used for flowers, trees, vegetables and others. It is a high quality organic mixed fertilizer which when applied to the cultivation of plants can improve soil structure, increase soil fertility and promote crop growth. The use of such fertilizers will not only reduce the burden of urban waste, but also promote the mass production of organic fertilizer and reduce the use of chemical fertilizers, thereby reducing the pollution of soil and water by chemical fertilizer.
Agro-Food Wastes for Production of Biofuels : Alternative Energy Generation
This is a very important emerging area, particularly in the light of rapidly rising costs associated with energy supply and waste disposal and also, the increasing public concerns with regards to environmental quality degradation. Viewed from the angle that sustainability
is a key principle in natural resource management, and it involves operational efficiency, minimization of environmental impact and socio-economic considerations, all of which are interdependent. A typical example is found in the rice processing plants in which raw rice is first of all dehusked, with such husks constituting serious environmental concern since it would not be easy to dispose of them. However, such husks can be collected and used to fire boilers during the parboiling of paddy. This will save such an establishment a lot of money that could be channelled into other sectors of the plant. Another example is found in the groundnut processing plant. Dried groundnut shells are usually used as alternate energy provider during groundnut oil production. Husks, hulls, chaff and stalks generated in other cereals and pulse processing industries as well as in the spices and condiments processing plants are also used as fuel to generate heat. In recent times husks from the cereals and grains processing factories have found use in the production of briquettes (pellets), which are now used for domestic heating.
Domestic food wastes can also be sources of biogas that can be used in plants. Due to relatively high moisture content of food wastes, bioconversion technologies such as anaerobic digestion are more suitable compared to thermo-chemical conversion technologies such as combustion and gasification. Anaerobic digestion has been widely applied for treatment of organic wastes that are easily biodegradable. These wastes are rich in lignocellulolytic materials, one of the largest and renewable sources of energy on earth. Significant improvement in biogas production occurs after pretreatment of these compounds with cellulases and cellulose producing microorganisms. Microbial enzymatic hydrolysis of different complex organic matter converts them into fermentable structures, leading to production of biogas. Significant improvement in biogas production occurs when crude and commercial enzymes are used in the pretreatment of complex organic matter.
Bio-fuels: bridging food with energy security
A bio-fuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter. Biofuels can be derived directly from plants (i.e. energy crops), or indirectly from agricultural, commercial, domestic, and/or industrial wastes.
Bio methane
Biogas is methane produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can be used as a biofuel or a fertilizer. Biomethane is upgraded or sweetened biogas after the removal of the bulk of the carbon dioxide, water, hydrogen sulfide and other impurities from raw biogas. From a functional point of view, biomethane is extremely similar to natural gas (which contains 90% methane) except that it comes from renewable sources.
Biodiesel
Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using transesterification and is a liquid similar in composition to fossil/mineral diesel. Chemically, it consists mostly of fatty acid methyl (or ethyl) esters (FAMEs).
Efficient feedstocks.: Sugar cane is an efficient crop (in terms of yield per unit of land), but its sustainability hinges largely on water availability and the crop does better when there is ample rainfall and minimal need for irrigation Besides high biomass, sugar cane also produces a range of useful byproducts all contributing positively to its economic competitiveness. Sugarcane continue to be attractive even under second generation technologies as bagasses can be a prime feedstock source. Sugar cane also offers the possibility of using molasses (i.e. sugar production by-products) for biofuel in situations where sugar production has priority over biofuels (as in India). Next to sugar cane, palm oil is by far the most efficient source for biodiesel (yield per unit of land), far exceeding alternatives like rapeseed, soybeans or sunflowers. Another potential alternative feedstock for biodiesel is the non-edible crop-Jatropha. Jatropha is drought-tolerant, has low input requirements and is highly suitable for marginal lands. Jatropha can also improve the soil quality because of its deep root system; however, clearing Jatropha land for conversion into crop land would be a considerable investment. Equally important is Jatropha’s suitability for small scale production as its seeds can be easily stored before processing. However, large scale biodiesel production is capital-intensive and thus requires tight supply arrangements such as out-grower schemes, in which producers deliver directly to local processing plants to ensure economic viability. India has been particularly keen on developing Jatropha for biodiesel in line with its non-food biofuel policy.
Bioethanol : Power alcohol from Organic Waste
Bioethanol is a biofuel used as a petrol substitute, produced by simple fermentation processes involving cheaper and renewable agricultural carbohydrate feedstock and yeasts as biocatalysts. A variety of common sugar feedstock including sugarcane stalks, sugar beet tubers and sweet sorghum are used. Cassava has also been targeted as a potential feedstock for ethanol because of its high starch content and high yield potential per hectare.
From a sustainability perspective, biofuels can contribute to increased energy security, help reduce GHG emissions, improve air quality in cities and, in the process, spur growth in rural areas.
Final conclusions and ways forward
Indeed, generation of wastes remains major fallout of almost every activity of man including agro-food production and processing activities, and these has far reaching implications for environment and health generally, demanding that measures must be taken to manage them if the unpleasant consequences of their accumulation must be averted. Unfortunately, most waste management options adopted over time had tended to see waste as useless entity that must be disposed off wholesomely. However, a close look at most natural systems gives a verdict that omnipotent and omniscient creator abhors wastages of any kind, since nature has a way of recycling every bit of its resources into usefulness. Keying into this,
biotechnological concepts see wastes from a different perspective, since what is regarded as waste may not be truly totally so. This is particularly evident in agro-food wastes because most of what is often considered as wastes consigned to the waste bins contain reasonable percentage of salvageable (biomass) resources that are bioconvertible into useful products entrapped therein. With respect to these, the role of modern technology, particularly biotechnology in resource exploitation can hardly be overstated, as is evident in the wide range of useful resources: animal foods and feeds, biofertilizers, industrial chemicals/raw materials, biofuels, biogas and other energy renewable alternatives, etc. derived out of the so-called waste, using the tool of biotechnology. Thus, based on the enormous resources recoverable from agro-food processing wastes using the tool of biotechnology, it is convincingly and conclusively found that wastes are veritable resources for wealth creation, and economic prosperity, since these products serves various purposes ranging from being consumer products in themselves or raw materials for production of various other products with various optional uses or applicability in different sectors of the economy.
What is needed is rethinking a new approach that integrate sustainability with the pursuit of renewable energy strategies and food security that is inclusive of marginal and small scale stakeholders. What is required as a more coherent and integrated framework for sustainability that combine both private schemes and public regulations in such a way as to assure inclusive processes, between large enterprises and small scale producers, as well as
countries goals and interests. Rethinking sustainability also require incorporating full environmental costs in economic cost-benefit assessments and fostering business models that can reconcile sustainability with economic growth and integrate inclusive-development with
food security. Also required are policies, regulations and incentives that broaden the biofuel development options to include small-scale locally harnessed renewable energy technologies and systems. Finally, biofuel sustainability will need to be mainstreamed into larger trends towards sustainable and climate-smart agriculture in line with the triple objectives of enhanced productivity, strengthened food security and climate change adaptation and mitigation.
Let’s raise the Slogan “TRASH TO CASH” to create
awareness.
Dr Mir Asmat is phd holder from SKUAST-K
