Sultan Ahmed Ismail

An Introduction to Anaerobic Digestion of Organic Wastes

The problem of waste disposal from a myriad of industries, is becoming increasingly acute, the world over. The burning of such wastes in open dumps or in poorly designed incinerators could be a major source of air pollution (Ndegwa and Thompson. Bioresour Technol 76:107–112, 2001). On the other hand, open dumps and poorly designed sanitary landfills can pollute surface and ground waters causing public health hazards. Meanwhile, the unavailability and rising cost of land near urban areas have made dumps and landfills increasingly expensive and impractical. The production of both livestock and grain on the other hand has increasingly relied on enormous chemical and energy inputs, leaving soils depleted of indigenous nutrients and organic matter, and resulting in wide-scale surface and groundwater contamination. As discussed earlier, recycling and utilization of organic wastes and by products through development of an economically viable, socially accepted and eco-friendly technologies are required. Over the years an array of innovative ideas for the utilization of these wastes have been put forward (Callaghan et al. Bioresour Technol 67:117–122, 1999) to increase productivity and to meet the heavy demand for food of the growing population (Jeyabal and Kuppuswamy. Eur J Agron 15:153–170, 2001). But these wastes could not be fully exploited without a viable technology for their economic recycling. It is well demonstrated that both fresh and composted amendments over these waste materials are potent to stimulate soil biological activities. Fresh wastes produces an initial burst of biochemical activity by the releasing easily degradable organic compounds whereas compost induces lower biochemical activities but more resistance to soils (Masciandaro et al. Soil Biol Biochem 32:1015–1024, 2000). Biological treatments plays a pivotal role in treating organic wastes these days. Among them, anaerobic digestion is frequently the most cost effective method because of the high energy recovery and its limited environmental impacts. Biogas production throughout Europe, could reach over 15 million m3/day of methane reported during 1998 (Tilche and Malaspina. Biogas production in Europe. Paper presented at the 10th European conference biomass for energy and industry, Wurzburg, 8–11 June, 1998). Presently, biogas production is considered to be an inevitable way of energy production.

Distribution of earthworms in Madras

Distribution of earthworms has been studied in four locations comprising of two sandy loam and two clay loam soils of Madras, and correlated with the physical and chemical parameters of the soil.L. mauritii andO. serrata are the dominant earthworm species in the sandy loams and clay loams respectively. Each location has limiting factors like temperature, moisture and/or soil texture which strongly govern the density and diversity of earthworm populations in that region.

Vermicomposting biotechnology: recycling of palm oil mill wastes into valuable products

BackgroundPalm oil mill effluent and palm press fiber are problematic wastes generated by the palm oil mill industries in Malaysia. This study has endeavored to assess the possibility of the vermicomposting of residue from the palm oil mills using epigeic earthworms Lumbricus rubellus under laboratory conditions. The study was conducted over 50 days using four combinations in three replicates of each treatment as palm oil mill effluent: palm press fiber in 50:50 ratio (T1), palm oil mill effluent/palm press fiber/cow dung in 50:25:25 ratio (T2), palm oil mill effluent/palm press fiber/cow dung/lawn clipping in 50:20:15:15 ratio (T3), and only palm press fiber (T4). Twenty healthy adult L. rubellus with average weight of 3.92 g was introduced.ResultsResults showed that T3 has a significant decrease in C/N ratio (14.81 ± 0.07) compared to the other treatments. The presence of cow dung and lawn clipping in the mixtures makes it more suitable for vermicomposting process as early compost productions were recorded in T2 and T3.ConclusionThe study showed that the major polluting problem in palm oil mills can be tackled through vermicomposting technique. Based on the results, vermicompost is found suitable for agriculture purposes as an organic fertilizer as well as soil conditioner.

Prospects of Organic Waste Management and the Significance of Earthworms

Each year, approximately 38 billion metric tons of organic wastes are produced all over the world. Human behaviour, consumption rate, and population explosion are the generally proposed factors responsible for this dramatic increase. As wastes materials are always considered to be either unusable or disposable, burning and deposition has always been the result. Burning and deposition in turn results in numerous environmental problems. Burning pollutes atmosphere whereas land disposal of organic waste materials may directly or indirectly alter the heavy metal status of the soil by affecting metal solubility or dissociation kinetics (Del Castilho et al. J Environ Qual 22:689–697, 1993). In order to deal with this challenging area, various treatment methods and practices have been formulated and applied by countries all over the world. Hence, much attention has been paid to convert such nutrientrich organic waste materials into useful outcome for sustainable agricultural practices (Suthar Biorem. J 13(1):21–28, 2009). The utilization of the organic materials of animal and plant origin is a viable means of improving soil fertility and a reliable way of disposing wastes (Adegunloye et al. Pak J Nutr 6(5):506–510, 2007). Solid organic waste is understood as organic-biodegradable waste with a moisture content below 85–90 % and these organic materials are recycled by a variety of decomposer microorganisms such as bacteria, fungi and detritus-feeding invertebrates.

Composting: A Traditional Practice of Waste Treatment

The intensity and concentrated activity of the livestock industry and other sources generate vast amounts of biodegradable wastes, which must be managed under appropriate disposal practices to avoid a negative impact on the environment (odour and gaseous emissions, soil and water pollution, etc.) (Burton and Turner. Manure management, 2nd edn. Treatment Strategies for Sustainable Agriculture Silsoe Research Institute, Lister and Durling Printers, Flitwick, 2003). Micro-organisms are largely responsible for the cycles of the elements within a soil and are involved in decomposing of organic substances at the ecosystem level (Bastida et al. Appl Soil Ecol 40:318–329, 2008). Composting process can substantially reduce the environmental problems associated with the treatment of wastes by transforming them into stabilized and safer materials in order to apply on soil by employing microbial activities (Carr et al. Commercial and on-farm production and marketing of animal waste compost products. In: Steele K (ed) Animal waste and the land–water interface. Lewis Publishers, Boca Raton, pp 485–492, 1995). Schematic representation of evolution of organic substances during composting process is shown in Fig. 3.1. Composting cannot be considered a new technology since it has been used by our ancestors as a traditional practice for agriculture based wastes (Chauhan and Singh. World J Zool 7(1):23–29, 2012), but amongst the waste management strategies it is gaining interest as a suitable option for manures with economic and environmental profits. Composting eliminates or reduces the risk of spreading of pathogens, parasites and weed seeds associated with direct land application of manure and leads to a final stabilized product which can be used to improve and maintain soil quality and fertility (Larney and Hao. Bioresour Technol 98:3221–3227, 2007). Composting provides a means of recycling solid wastes and has the potential to manage most of the organic material in the waste, animal manure, paper products, sewage sludge and domestic wastes (Adegunloye et al. Pak J Nutr 6:506–510, 2007). However, depending on the production of good quality compost, specifically, compost that is mature and sufficiently low in metals and salt content (Hargreaves et al. Agric Ecosyst Environ 123:1–14, 2008), the compost will be suitable for plants.

Microbial Ecology Associated with Earthworm and Its Gut

Soil bears infinite life that promotes diverse microflora. Soil bacteria viz., Bacillus, Pseudomonas and Streptomyces etc., are prolific producers of secondary metabolites which act against numerous co-existing phytopathogeic fungi and human pathogenic bacteria (Pathma and Sakthivel. SpringerPlus 1:1–26, 2012). Microbial communities also support a large number of soil invertebrates, which in turn have an important regulatory effect on the microbial populations (Edwards. Earthworm ecology, 2nd edn. CRC Press, Boca Raton, 2004). Decomposition of organic material is assumed to be mainly mediated by microorganisms. The rate and extent of the decomposition depends on the chemical composition of the material, environmental factors, and on the microbial community. The activity of the decomposing microorganisms is accelerated by the activity of the soil fauna (Schonholzer et al. FEMS Microbiol Ecol 28:235–48, 1999). According to Lavelle and Spain (Soil ecology. Kluwer Academic Publishers, Dordrecht, 2001), microorganisms show a high degree of specialization and display a large number of enzymes for the breakdown of organic matter. It is certainly proven that the growth of earthworms is dependent on microbial associations. In fact, microorganisms are largely responsible for the decomposition of the materials ingested by earthworms and in turn earthworm regulates modifications in microbial communities thus sharing a mutualistic relationship.

Vermicomposting: An Earthworm Mediated Waste Treatment Technique

Biodegradable organic wastes such as crop residues, municipal, hospital and industrial wastes pose major problems in disposal and treatment. Release of unprocessed animal manures into agricultural fields contaminates ground water causing public health risk (Gandhi et al. Environ Ecol 15:432–434, 1997). Vermicomposting and composting are the most efficient way for converting sludge into useful products. These two well-established processes have been adopted for solid organic waste reclamation – and the final products, composts and vermicomposts, can be used as sources of organic matter for soil amendment, as sources of nutrients for soil fertilization or as growing media constituents for soilless cultivation (Gonzalez et al. Bioresour Technol 101:8897–8901, 2010). Lorimor et al. (Manure management strategies/technologies. White paper on animal agriculture and the environment for national center for manure and animal waste management. Midwest Plan Service, Ames, 2001) concluded that, compared to conventional composting system, the vermicomposting often results in mass reduction, shorter time for processing, and high levels of humus with reduced phytotoxicity in ready material. Vermiculture is a cost-effective tool for environmentally sound waste management (Banu et al. J Environ Biol 22:181–185, 2001; Asha et al. J Hum Ecol 24:59–64, 2008). This low cost technology uses earthworms as bio-agents to treat waste materials (Alidadi et al. Iran J Environ Health Sci Eng 2(4):251–254, 2005). Reduction of particle size and increased nutrient availability in the vermicomposted outputs are reported by many researchers (Ndegwa and Thompson. Bioresource Technol 76:107–112, 2001).

Earthworms as plug flow reactors: a first-order kinetic study on the gut of the vermicomposting earthworm Eudrilus eugeniae

Earthworms are commonly referred as environmental engineers and their guts are often compared with chemical reactors. However, modeling experiments to substantiate it are lacking. The aim of this study was to use established reactor models, particularly PFR, on the gut of the vermicomposting earthworm Eudrilus eugeniae to understand more on its digestion. To achieve the objective, a mathematical model based on first-order kinetics was framed and used to determine the pattern of digestion rates of nutrient indicators, namely total carbon (%), total nitrogen (%), C/N ratio, 13C (‰), and 15N (‰) at five intersections (pre-intestine, foregut, midgut A, midgut B, and hindgut) along the gut of E. eugeniae. The experimental results revealed that the concentrations of TC, TN, 13C, and 15N decreased during gut transit, whereas C/N ratio increased. The first-order model demonstrated that all the nutrients exhibit a linear pattern of digestion during gut transit, which supports the PFR model. On this basis, the present study concludes that the gut of E. eugeniae functions as PFR.

The phytoextraction potential of selected vegetable plants from soil amended with oil palm decanter cake

PurposeThe investigation of the phytoextraction potential of three vegetable plants grown in soils amended with decanter cake.MethodPot experiments were conducted to investigate the response of decanter cake composition on the phytoextraction of metals (Mg, Zn, Ni and Cu) by lady’s finger, tomato and brinjal plants. The phytoextraction properties of these plants were determined by calculating the bioconcentration and translocation factors at different decanter cake amendments (10, 20 and 30%).ResultsResults indicated that in all three plants, there was no transfer of excess metal ions from the control soil or amendments to the fruit portion as evidenced by bioconcentration factor (BCF). In addition, substantial amount of the metals was found to be accumulated in the roots and shoots, which depicts the phytoextraction ability of these vegetable plants. The translocation factors (TF) of the three plants were found to be higher than control plants. The accumulation of metal ions did not exceed the permissible standards for vegetables thus rendering the fruits safe for human consumption.ConclusionOn the basis of significant findings, lady’s finger, tomato and brinjal plants were not found to be suitable for phytoextraction of metals as both BCF and TF were not greater than 1.

Vermicompost, Its Applications and Derivatives

Vermicomposts are products derived from the accelerated biological degradation of organic wastes by interactions between earthworms and microorganisms as we have discussed in previous chapters. Earthworms consume and fragment the organic wastes into finer particles by passing them through a grinding gizzard, and they derive their nourishment from the microorganisms that grow on the organic matter. The process accelerates the rates of microbiological decomposition of the organic matter, increases microbial populations, and alters the physical and chemical properties of the material, leading to accelerated humification, during which the unstable organic matter is fully oxidized and stabilized (Albanell et al. Biol Fertil Soils 6:266–269, 1988). Vermicomposts are finely divided peat-like materials with high porosity, aeration, and drainage and good water-holding capacities (Edwards and Burrows. The potential of earthworm composts as plant growth media. In: Edwards CA, Neuhauser E (eds) Earthworms in waste and environmental management. SPB Academic Press, The Hague, pp 21–32, 1988; Edwards and Arancon. BioCycle 45:51–53, 2004). High-quality vermicompost has a good physical texture and color, no odors, and few contaminants or pollutants (Edwards. Breakdown of animal, vegetable and industrial organic wastes by earthworms. In: Edwards CA, Neuhauser EF (eds) Earthworms in waste and environmental management. SPB, The Hague, pp 21–31, 1988; Edwards and Arancon. BioCycle 45:51–53, 2004). Vermicomposts are suitable both as plant growth media and as soil amendments. Graphical representation of percentage recovery of vermicasts from earthworms is shown in Fig. 9.1.