Spices processing, Beverage Industries, Landscaping: waste characteristics, management, value addition

Black Pepper Husk is the skin of Black Pepper with the traits of pepper (both hotness and aroma). The Black Pepper Husk is majorly used for grinding purposes. It has mild taste and aroma of Black pepper.

Cardamom Husk is the outer skin of green cardamom and is of green color. It carries the taste, flavor and aroma of Green Cardamom. It can be used in grinding.

Cinnamon Spent taste, flavor and aroma of Cinnamon. It is also used for grinding purpose.

Spent turmeric which is being used as an industrial waste, proves to be a good antidiabetic activity by inhibiting the key enzymes linked to type 2 diabetes.

Spent ginger obtained after extraction of oleoresin constitutes more than 90% of the raw material and rich in carbohydrates that could be used as a substrate for the production of bioethanol.

The spent residue from cumin, not having much commercial value, can be a rich source of useful dietary fiber and can find food applications. It can be an effective way of utilizing industrial waste from the point of view of environmental pollution from the residues of spice processing industries.

Red Chilli Spent is a powder derived after extraction of Oleoresins. Usually it is used for biofuel production. Chenguang Biotech (India) Pvt. Ltd, a factory in Mudigonda of Khammam district of, Hyderabad was in controversy in disposal of spent chillies that extracts colour and capsicum pigment from chilli, selling ‘chilli spent’ that is treated with chemicals like acetone and hexane for human consumption. The chilli spent product was not for human or animal consumption and was for use as bio-fuel. They procure red and dried chilli from the local markets and farmers  and extract natural colorants, the seeds come out during the first phase of etraction through a mechanical process. The rest is crushed into powder and made into pellets. In the second phase, the pellets are applied with chemicals like solvents of acetone and hexane, which absorb colour. After the absorption the   chilli spent was obtained. The chemicals were evaporated and sold as dry spent. The natural colorants/final product is exported out of the country and is used for food and medicinal purpose. The spent chilli used for boiler firing, fertilisers and at kilns for baking bricks.

Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and hydrolyzable tannins that results dark tan/brown colour effluent which cannot be discharged to the environment without proper treatment.

White pepper is the de-husked berry produced by removing the outer skin, pericarp and outer portion of the mesocarp of the well matured berries or in some cases dried black pepper. Black pepper gets the colour due to the enzymatic browning by fermentation and oxidization of phenolic compounds present in the outer skin of fruits. White pepper has demand in high the European markets due to its colour and lower pungency. Traditional retting includes washing, soaking, pulping, washing and drying, and soaking is done for 3 to 5 days. When black pepper is used as the raw material, soaking requires about 2 m³ of water per tonne. The wastewater discharged from soaking is rich in organic matter including tannins adding a dark tan colour. Gallotannin, or common tannic acid, is the best known hydrolyzable tannin and it leach into the effluent during soaking and produce undesirable dark brown color. Treatment of pepper wastewater at industrial level has become a great challenge due to its peculiar colour and high BOD₅ value above 3500 mg/L.

India is the 4th largest pepper producer in the world, production of 67,000 metric tons in 2008. Annual white pepper contribution in India is less than 250 metric tones against the world demand of more than 1,50,000 metric tones. Indonesia is the largest white pepper producing country, converts about 50 % of its pepper to white. Malaysia and Brazil convert about 10 % and 5% of their pepper to white respectively.

There are chemical, biological and physical methods for the conversion of pepper into white pepper. Natural retting can be used to remove the skin, but requires long time (7-15 days) steeping the pepper in stagnant or running waters. Major limitations of this retting process include quality deterioration of the product.

During the process pectin, the intercellular cementing substance present in the pulpy upper mesocarpic area of pepper skin is degraded and breaks apart from the core. The pectin degradation is effected through release of pectinases by the bacteria grown in the anaerobic system. The best operational conditions for biological skin removal through the anaerobic process are in temperature between 30 to 37_­^oC and neutral pH.

The rhizomes of turmeric are processed to obtain oleoresin and subsequently curcuminoids are isolated. The mother liquor, after partial isolation of curcuminoids, known as spent turmeric oleoresin (STO), is considered as industrial waste.

India is the largest producer of turmeric in the world with annual production of more than 4 lakh tonnes i.e. nearly 90% of global produce. About 8% is exported and rest is consumed locally. Andhra Pradesh and Tamilnadu jointly account for over 50% of turmeric production. Kerala, Maharashtra, Karnataka, Orissa and Bihar are other important producing states. While polishing 4% is waste is emitted as dust that can be composted using traditional pit method of composting

Beverage industries

Soft drink wastewater consists of wasted soft drinks and syrup, water from the washing of bottles and cans, which contains detergents and caustics, and finally lubricants used in the machinery. Therefore, the significant associated wastewater pollutants will include total suspended solids (TSS), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), nitrates, phosphates, sodium, and potassium higher organic contents indicate that anaerobic treatment is a feasible process.

Biological treatment is the most common method used for treatment of soft drink wastewater because of the latter’s organic content. Since BOD₅ and COD levels in soft drink wastewaters are moderate, it is generally accepted that anaerobic treatment offers several advantages compared to aerobic alternatives. Anaerobic treatment can reduce BOD₅ and COD from a few thousands to a few hundreds mg/L; it is advisable to apply aerobic treatment for further treatment of the wastewater so that the effluent can meet regulations. High-strength wastewater normally has low flow and can be treated using the anaerobic process; low-strength wastewater together with the effluent from the anaerobic treatment can be treated by an aerobic process.

A complete biological treatment includes optional screening, neutralization/equalization, anaerobic and aerobic treatment or aerobic treatment, sludge separation (e.g., sedimentation or dissolved air flotation), and sludge disposal. Chemical and physical treatment processes (e.g., coagulation and sedimentation/flotation) are occasionally used to reduce the organic content before the wastewater enters the biological treatment process. Since the wastewater has high sugar content, it can promote the growth of filamentous bacteria with lower density. Thus, dissolved air flotation may be used instead of the more commonly used sedimentation.

Owing to the high organic content, soft drink wastewater is normally treated biologically; aerobic treatment is seldom applied. If the waste stream does not have high organic content, aerobic treatment can still be used because of its ease in operation. The removal of BOD and COD can be accomplished in a number of aerobic suspended or attached (fixed film) growth treatment processes. Sufficient contact time between the wastewater and microorganisms as well as certain levels of dissolved oxygen and nutrients are important for achieving good treatment results. An aerobic membrane bioreactor (MBR) for organic removal as well as separation of biosolids can be used in the wastewater treatment

Landscaping waste management

Removal of earth from the land is called cutting while when earth is added to the slope, it is called filling. Sometimes the grading process may involve removal of excessive waste (landfills), soil and rocks, so designers should take into account while in the planning stage

Maintenance of green spaces such as home gardens, parks, lawns and other green interiors produces a significant amount of green waste, includes foliage, plant residues, decayed and fallen flowers, garden refuse, leaf litter, cut grass, pruned things of trees, weeds and other organic matter discarded from gardens but exclude organic waste of the type obtained from municipal collections.

India is blessed with huge land cover, relatively high population density, and green consciousness, much land is left undeveloped. The number of parks and other recreational centers, home gardens etc. contribute to the increasable quantum of garden biomass generation. Consequently, maintenance of green areas produces a significant amount of waste.

The total annual production of leafy biomass in India is of the order of 1130 million tons. This green waste would land in dumping sites, or will be burned if not collected and processed contributing to the large scale contamination of land, water and air. Although not in focus as much as domestic green waste such as foliage, grass, and plant residues, is a major constituent of solid waste. Leaves accumulating in the urban and suburban locations such as sidewalks, lawns, and playgrounds are not only an unseemly sight but adds to the overall problem of municipal solid waste disposal. Road sweepings and road side plantations are some areas which generate significant biomass waste.

Leaving a thick layer of leaves on your lawn or garden can create conditions that lead to rotting of the grass or perennials beneath. In India and several other countries foliage is often piled-up and set on fire. The resulting ash returns some of the NPK content of the foliage to the soil but much of nitrogen, phosphorous, and organic carbon gets lost. The burning of leaves also adds to air pollution and global warming.

Green waste when decomposes in soil may release methane and foul odors, before getting converted to humus. Leaves and yard trimmings can be harmful to lakes and streams after washing into storm sewers.

The use of green waste as a raw material can broaden the options giving it more flexibility and a broader application range because it would (1) rely on more-biodegradable products and processes that create less pollution and generally have fewer harmful environmental impacts; (2) develop less expensive products;(3) use less expensive raw materials. Green waste contains recalcitrant or complex compounds such as cellulose and lignin, and relatively small amounts of saccharides, amino acids, proteins, aliphatic compounds and carbohydrates.

The main components of plant biomass are carbohydrates (approximately 75%, dry weight) and lignin (approximately 25%), which can vary with plant type. The carbohydrates are mainly cellulose or hemicellulose fibers, which impart strength to the plant structure, and lignin, which holds the fibers together. Some plants also store starch (another carbohydrate polymer) and fats as sources of energy, mainly in seeds and roots.

Technologies available for green waste processing

Composting is the biological oxidative decomposition of organic constituents in wastes under controlled conditions. It requires special conditions, temperature, moisture, aeration, pH and C/N ratio, to enable optimum biological activity during the different stages of composting. The main products of aerobic composting are CO₂, H­₂O, mineral ions and stabilized organic matter, often called humus. CO₂ and water losses can amount to half the weight of the initial materials.

The major groups of microorganisms that participate in composting are bacteria, fungi, and actinomycetes. The process is accomplished through different phases i.e. initial phase during which readily degradable components are decomposed

During a thermophilic phase cellulosic materials are oxidatively degraded rapidly by microbes. This is followed by maturation and stabilization phases

Vermicomposting of neem (Azadirachta indica A.Juss) was accomplished in highrate reactors operated at the earthworm (Eudrilus eugeniae) densities of 62.5 and 75 animals per litre of reactor volume. Vermicomposting of leaf litter ensuing from the trees of mango (Mangifera indica) is possible. After over nine months of continuous operation the vermireactors with 62.5 animals l^-1 generated 13.6g vermicast per litre of reactor volume (l) per day (d) whereas the reactors with 75 animals l^-1 produced 14.9g vermicast l^-1 d ^-1.

Almost any organic material is suitable for composting process. The materials need a proper ratio of carbon-rich materials ‘browns’ and nitrogen-rich materials ‘greens’. Among the brown materials are dried leaves, straw and wood chips. Nitrogen materials are fresh or green such as grass clippings and kitchen scraps. The carbon provides energy for the microbes, and the nitrogen provides proteins. Achieving the best mix is more an art gained through experience than an exact science. The change in the C/N ratios reflects the organic matter decomposition and stabilization achieved during composting.

The decomposition of organic matter is brought about by living organisms, which utilize carbon as a source of energy and the nitrogen for building cell structures. If the C/N ratio of compost is more, the excess carbon tends to utilize nitrogen in the soil to build cell protoplasm. This results in loss of nitrogen of the soil and is known as robbing of nitrogen in the soil. If on the other hand the C/N ratio is too low the resultant product does not help improve the structure of the soil. It is hence desirable to control the process so that the final C/N ratio is less than or equal to 20.

Green waste composting is an environment friendly method as it produces fairly hygienic products. During incubation process the high temperatures were successfully went through as problems of foul odour and presence of pathogenic organism were not observed.  It is easy to carry out and produces products that deliver fertilizer efficiency between humic soil and organic fertilizer. 

Composting is an appropriate method to deal with the green waste for military barracks, schools, institutions and commercial areas which consist of large green areas, undeveloped land and plenty of labor.  Large quantities of green waste can be managed in sustainable matter.  Organic matter and nutrients return to the natural cycle through the application of compost to the soil.  Activity of earthworms and other natural soil organisms beneficial for plant growth increases with the use of compost 

Long time duration, space requirement and need for manpower are the major shortcomings for this eco-friendly technology.  As it contains only limited levels of plant nutrients compost is a soil emendation, not a fertilizer.  Loss of nitrogen, VOCs, protracted processing and curing time, cost of equipment, and the challenge of augmenting a successful marketing plan for compost.

Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. In the first step polymers like starch, cellulose, lipids, proteins are hydrolyzed to amino acids, sugars, fatty acids etc. In the process of acidogenesis these are converted into a mixture of hydrogen gas, low molecular weight acids like acetic acid and carbon dioxide. In the process of methanogenesis these are reacted together to generate methane. Anaerobic digestion is broadly used as a renewable energy source because the process produces biogas which is rich in methane and carbon dioxide suitable for the production of energy that can replace fossil fuels. The digestate left after biogas production is rich in nutrient value and can be used as fertilizer.

Biomass sludge is produced in less quantity as compared to aerobic treatment technologies.  The method proved successful in treating wet wastes having less than 40% dry matter.  Produces minimal odour as 99% of volatile compounds are oxidatively decomposed upon combustion, e.g. H₂S forms SO₂.  Slurry produced is an enhanced fertilizer for plants due to its availability and rheological properties. Anaerobic digestion is more expensive than composting.

Green waste briquetting is the process of compaction of residues into a product of higher density than the original raw material is known as briquetting. Biomass briquettes are generally made from agricultural waste and are a replacement for fossil fuels such as oil or coal, and can be used to heat boilers in manufacturing plants, and also have applications in developing countries. Biomass briquettes are a renewable source of energy and avoid adding fossil carbon to the atmosphere. Use of biomass briquettes can earn Carbon Credits for reducing emissions in the atmosphere. Biomass briquettes also provide more calorific value/kg and save around 30-40 percent of boiler fuel costs.

Briquetting has aroused a great deal of interest in developing countries all over the world lately as a technique for upgrading of residues as energy sources. The process also helps to reduce deforestation by providing a substitute for fuel wood.

Two different types of briquetting technologies are currently in use. The first, called pyrolizing technology relies on partial pyrolysis of biomass, which is mixed with binder and then made into briquettes by casting and pressing.

The second technology is direct extrusion type, where the biomass is dried and directly compacted with high heat and pressure. Setting up the briquette production unit raw material should be locally available.

Reed canary grass (RCG, Phalaris arundinacea L.) an interesting new source of raw material for the pulp and paper industry in northern Europe. Pulp produced from briquetted RCG had more fines as compared to the non-briquetted reference material. Hand sheets produced using pulp from briquetted RCG were thinner, denser, and had lower air permeability compared to the non-briquetted reference material. The strength properties of pulp made from briquetted RCG indicated little or no difference compared to the reference material.

Biomass briquettes offer many benefits over traditional fuels like coal, fuel oil, natural gas and propane as well as over the pre-compacted raw materials like wood chips, paper, green wood etc.  The purchase price of biomass briquettes is less than natural gas, propane and fuel oil.  Compacting biomass waste into briquettes reduces the volume by 10 times, making it much easier to store and transport.  They have a long shelf-life

Briquettes are immeasurably cleaner than the other fuel alternatives.  Briquettes burn in a controlled manner, slow and efficiently.  Product has consistent quality, burning efficiency also ideally sized for complete combustion.  It helps to solve the problem of residue disposal.  It is one of the alternatives to save the consumption and dependency on fuel wood.  The technology used is pollution free and ecofriendly.

Cellulosic ethanol from green waste

 Green waste is a popular cellulosic material for ethanol production. As world reserves of petroleum are depleting fast, in recent years ethanol has emerged as most important alternative resource for liquid fuel and has generated a great deal of research interest.

The research on improving ethanol production has been accelerated for both ecological and economical reasons, mainly for its use as an alternative to petroleum based fuels. The most abundant organic raw material in the world is lignocellulosic biomass; production of ethanol from renewable lignocellulosic resources may improve energy availability. Utilization of these wastes will reduce dependency on foreign oil and secondly, this will remove disposal problem of wastes and make environment safe from pollution.

Pretreatment is prerequisite to make lignocellulosic biomass accessible to enzymatic attack (either by microorganisms or enzymes), by breaking the lignin seal, removing hemicellulose, or disrupting the crystalline structure of cellulose. Pretreatment alters the structural features of biomass which are classified as physical or chemical. The chemical structural features involve the compositions of cellulose, hemicellulose, lignin, and acetyl groups bound to hemicellulose whereas physical structural features include the accessible surface area, the crystallinity, and the physical distribution of lignin in the biomass matrix, the degree of polymerization, the pore volume, and the biomass particle size.

Production of ethanol from green waste has the abundant and diverse raw material compared to sources like corn and cane sugars, but requires a greater amount of processing such as physical and chemical fiber pre-treatments including: grinding, pyrolysis, steam explosion, ammonia fiber explosion, CO₂ explosion, ozonolysis, acid hydrolysis, alkaline hydrolysis, oxidative delignification, organic solvent and biological pretreatment of the lignocellulosic materials to remove lignin and hemicellulose and reduce fiber crystallinity

The acid pretreated samples released more glucose than the lime treated ones (5.7% and 3.9% weight by weight (w/w, DS), respectively). Fermentation of the obtained glucose sources by Saccharomyces cerevisiae for 12 and 24 h, respectively, yielded ethanol at 4.8% and 8.0% (w/w, DS), respectively.

 International Bermuda grass as a promising feedstock for the production of fuel ethanol was also demonstrated. A variety of chemical, physico-chemical, and biological pretreatment methods have been investigated to improve the digestibility of Bermuda grass.

Batch fermentation of mahula (Madhuca latifolia L. a tree commonly found in tropical rain forest) flowers using immobilized cells (in agar-agar and calcium alginate) and free cells of Saccharomyces cerevisiae yielded ethanol concentration of 151.2, 154.5 and 149.1 g kg−1 flowers using immobilized and free cells, respectively.

 Ethanol is a renewable transportation fuel. The raw material for cellulose ethanol production is plentiful as cellulose is present in every plant.  Cellulosic ethanol exhibits net energy content three times higher than corn ethanol.

Bioplastics is the designation for innovative plastics manufactured from regenerative raw materials. They can replace the previously used fossil plastics and plastic materials in many applications. Apart from wood, cellulose is the most significant renewable resources in terms of quantities; around 1.3 billion tones are annually harvested for technical applications world-wide. However, chemical processes are necessary to separate the cellulose fibers from undesired by-products such as lignin and pentoses. Cellulose has potentials in the production of plastics. For example, cellulose esters are amorphous thermoplastics which contain special plasticizers or are modified with other polymers. They are characterized by high toughness and are often used as polymer components in compounds with other bioplastics.

Striving to achieve cost-competitive biomass derived materials for the plastics industry, the incorporation of starch (corn and potato) to a base formulation of albumen and glycerol was considered.

Bioplastic is made from renewable resources: corn, sugarcane, switchgrass, soy and other plant sources as opposed to common plastics, which are made from petroleum.  Energy efficiency – Production uses less energy than conventional plastics. 

Bioplastic also generates 68% fewer greenhouse gasses and contains no toxins (Safety).  Bioplastics reduces global warming, pollution and dependence on fossil fuels.  It represents 42% reduction in carbon footprint as per studies.  Bioplastics can be made from agricultural by products, from used plastics bottles and other containers using microorganisms.