Composting: Comparison
Please note this is a comparison between Version 2 by Camila Xu and Version 1 by Muhammad Waqas.

Composting is the most adaptable and fruitful method for managing biodegradable solid wastes; it is a crucial agricultural practice that contributes to recycling farm and agricultural wastes. Composting is profitable for various plant, animal, and synthetic wastes, from residential bins to large corporations. Composting and agricultural waste management (AWM) practices flourish in developing countries, especially Pakistan.

  • composting
  • biodegradability
  • decomposing
  • organic waste

1. Introduction

Composting is the biological conversion of the solid waste of plant and animal organic materials into a fertile matrix through numerous micro-organisms, including actinomycetes, bacteria, and fungi, in the presence of oxygen. The addition of diverse microorganism in a solid waste can convert it into compost or many by-products, .g., heat, water, and CO2 [17,18][1][2]. Humus is the solid and stable matrix after the microbiological process that can be usefully applied to land as an organic fertilizer to increase the fertility and structure of the soil. In ancient history, i.e., pre-Columbian Indians of Amazonia or ancient Egyptians and numerous prehistoric cultures used composting as a primitive technique for the betterment of soil. In the previous four decades, the composting technique has flourished, and its beneficial impact is illustrated with scientific research. The vulnerability and interconnection of various competing factors regarding the knowledge and process engineering of a composting matrix have been established [19,20,21][3][4][5].
Composting innovative processes were developed and employed by large- or medium-scale farmers, but they are expensive for small-scale farmers because the techniques require high-tech equipment for composting. Despite discrete processes/techniques, the crucial key points of the composting processes were indistinguishable each time, like natural, chemical, and physical characteristics. Appropriateness of distinctive input supplies and alterations and their fitting structure, substrate degradability, dampness management, energy, porosity, air space, energy adjustment, deterioration, and stabilization are needed to study and distinguish compost and composting processes [19,22][3][6].

2. Composting Stages

Composting processes undergo four stages: mesophilic, thermophilic, cooling, and finally ending with compost maturation; these stages can happen concomitantly rather than consequently [23][7] (Figure 2). Each stage duration depends on the mixture’s inceptive framework, water content, air circulation, and microbiological composition [24,25][8][9]. During the mesophilic phase, a combination of bacteria, fungi, and actinomycetes induce the rapid metabolism of C-abundant substrates. Moreover, this is accomplished by selecting tolerable temperatures, generally within 15–40 °C, because aerobic metabolism will produce heat. Transforming the matter and air circulation decreases the temperature, for the time being, reducing the rapid decay of other organic matter. Thus, the temperature rises once again, as shown in Figure 1. In the thermophilic phase (2nd stage), temperature increases to around 40 °C, favoring mostly thermophilic bacteria, e.g., bacillus. When C compounds are produced after substrate reduction, a modest temperature fall occurs followed by the cooling phase.
Figure 1.
Time, temperature, the progression of compost biota, and further processes during discrete stages in composting.
Fungi break down more complex structures and more resistant components like lignin and cellulose molecules. Additionally, actinomycetes play a crucial role in forming humic compounds via condensation processes and breakdown [25][9]. Using aerobic bacteria, the final composting maturity is characterized by lower oxygen uptake rates and temperatures < 25 °C. During this final phase, the breakdown of various organic components continues, and macrofauna and soil organisms enter. By metabolizing phytotoxic chemicals, the organisms of this phase have a favorable effect on compost maturation, e.g., plant disease suppression [26][10].
Consequently, compost quality improves primarily during maturation (final stage) [27][11]. The final product of composting is characterized by pH and a lower C/N ratio of 15 to 20 compared to the initial substrate composition. It may contain a significant amount of plant-available NO3, but NO4+ levels are low. Moreover, the intensity of the compost odor is significantly diminished [28][12]. However, it appears that the OM has stabilized, retaining recalcitrant C compounds [25][9]. Table 1 explains the favorable and sustainable application of different crop residues’ influence on numerous biological, chemical, and physical aspects during the different processes. The outcomes showed which method is best with respect to input residues and the desired output products.

3. Discrete Waste Composting

In contrast to landfilling, which elevates the pollution risk for groundwater, discrete waste composting techniques are environment friendly and avoid groundwater contamination since chemical pollutants and bacteria are reduced during composting. Composting permits persistent organic pollutants and endocrine disruptors to remain in the soil while beneficial bacteria break down the toxins. The elimination of these harmful chemicals has not been simple. Although numerous methods have been attempted to eradicate them, there is no agreed success rate. A thorough application can increase agricultural and environmental sustainability. It also improves soil OM content and enhances agricultural productivity [29][13] due to the availability of plant-growth-promoting organisms and sufficient nutrients in the composted debris [30][14] and significantly contributes to the certification of food safety. Compost is helpful for bioremediation [6][15], weed control [31][16], plant disease control [32][17], pollution anticipation [33][18], and erosion management, in addition to its use as fertilizer. Composting also increases soil biodiversity and reduces environmental risks associated with synthetic fertilizers [34][19].
Composting is a fundamental aspect of a comprehensive AWM strategy. The key strategy for practical integrated AWM is nutrition level improvement. Compost is rich in essential plant nutrients, e.g., nitrogen (N), phosphorus (P), potassium (K), sulfur (S), carbon (C), and magnesium (Mg), as well as various essential trace elements [26,35][10][20]. Consequently, compost can be described as an assortment of nutrient-rich organic fertilizers [36][21]. Compost processing parameters and organic feedstocks determine its key chemical features, e.g., C/N ratio and pH, as well as the content of other nutrients (Table 2). Total N, P, and K levels could contribute to soil fertility when used as soil amendment agents. By adequately combining these organic components, nutrient-rich compost substrates can be produced and used in agriculture in place of commercial mineral fertilizers. This aspect is discussed in the following subsections.
  • Crop residue waste
Global agricultural waste production is substantial, and crop leftover management is imperative [37][22]. In addition, waste disposal pollution necessitates research into eco-friendly methods for managing agricultural wastes as the increase in agricultural waste exacerbates aesthetic, health, and environmental issues. Consequently, research into secure disposal methods is necessary. Composting has evolved into an eco-friendly, cost-effective, and secure treatment technology; it is a productive method for intensifying and preserving agricultural products [38][23]. Biodegradable wastes, e.g., wood shavings, pine needles, dry leaves, sawdust, and coir pith, are commingled to maintain appropriate and durable humus [39][24]. However, lignin-rich plant products are difficult to decompose. Lime is used to accelerate the breakdown process in the garbage. These components are mixed at a ratio of 5 kg (lime) per 1000 kg (plant materials) to produce high-quality compost. Lime mixed with water may result in the formation of a semi-solid substance or a dry powder. Lime boosts humification of plant wastes by decreasing lignin structure and improving humus content [40][25]. Likewise, usable compost substrates can be generated from various crop leftovers using a suitable process and quality control procedures (Table 1).
  • Municipal solid waste (MSW)
Increasing population, industrialization, and urbanization has elevated the levels of MSW, which has become a problematic responsibility in Pakistan and worldwide [41][26].
The most well-known biodegradable waste procedures are microbiological stabilization and composting [42][27]. Due to the high organic content of MSW, composting is theoretically one of the most suitable AWM technologies for MSW management [43,44,45][28][29][30]. In addition, it generates a soil layer known as a conditioner with agronomic benefits, and is an economically viable and valuable method for offsetting the organic part of the trash. It also reduces the disposed waste, remarkably decreasing the residual waste’s pollution capacity and volume for landfilling. As a result, numerous developing Asian countries are turning to compost to manage their MSW. Picking, contaminant separation, sizing and mixing, biological decomposition, and other functions are all part of the modern MSW management composting system. Figure 2 shows the schematic flow diagram of the distinct method of MSW management from source to utmost disposal. To weigh Pakistan’s Lahore compost waste intake, a weighbridge having a capacity of 75 tons is located at the Mahmood Booti open dumping site operated by the City District Government of Lahore [46][31]. Composting is primarily a small-scale industry in Bangladesh and the Maldives. MSW composting in Indore and a large-scale aerobic device in Mumbai were installed in India in 1994 to control 500 metric tons of MSW [44][29]. These are the two examples of operational large-scale composting ingenuities in India [47][32]. By 2008, composting had been used to treat 9% of India’s MSW [44][29]. The average cost ranged from $25 to $30 per ton, while the market value per metric ton ranged from $33.5 to $42. India intends to add other plants in near future [48][33].
Figure 2.
Schematic flow diagram of MSW management by composting.
  • Biomedical waste (BMW)
The waste produced through the diagnosis, immunization, and treatment of human beings, research practices, and animal is organic BMW. In Pakistan, hospitals make approximately 2.07 kg of BMW per bed per day [49][34]. If BMW is not managed properly, it may cause serious environmental and health issues [50][35]. Therefore, safe disposal techniques need to be investigated, and composting is a sustainable option. Neem and tobacco extracts are commercially cost-effective for local small farmers and provide the best degradation of organic BMW. Thus, these extracts can be employed for conversion of organic BMW into potential fertilizer [51][36]. Previous research revealed that the BMW must be similarly treated with 5% sodium hypochlorite (NaOCl) at the disposal location [52][37]. It can be exposed to an initial decomposition process by mixing it with cow dung slurry, and then VC can be utilized to treat it further. Several epigeal species of worms may be used for this purpose. By using this approach to handle BMWs, these worms are more effective in decomposition. VC and proper handling of BMW can be energy-efficient and sustainable methods of eliminating and recycling this hazardous waste [52][37]. Meanwhile, the composting processes of various wastes come in discrete modes. The most utilized techniques are conventional composting, i.e., AC, AnC, and VC, and emerging composting, e.g., two-stage composting, as described below.
Table 1.
Treatment methodologies of different types of crop residues.
Table 2.
Physiographical properties of organic feedstock materials or different wastes.

References

  1. Dróżdż, D.; Malińska, K.; Kacprzak, M.; Mrowiec, M.; Szczypiór, A.; Postawa, P.; Stachowiak, T. Potential of fish pond sediments composts as organic fertilizers. Waste Biomass Valorization 2020, 11, 5151–5163.
  2. Żukowska, G.; Mazurkiewicz, J.; Myszura, M.; Czekała, W. Heat energy and gas emissions during composting of sewage sludge. Energies 2019, 12, 4782.
  3. Avidov, R.; Saadi, I.; Krassnovsky, A.; Hanan, A.; Medina, S.; Raviv, M.; Chen, Y.; Laor, Y. Composting municipal biosolids in polyethylene sleeves with forced aeration: Process control, air emissions, sanitary and agronomic aspects. Waste Manag. 2017, 67, 32–42.
  4. Ren, X.; Zeng, G.; Tang, L.; Wang, J.; Wan, J.; Wang, J.; Deng, Y.; Liu, Y.; Peng, B. The potential impact on the biodegradation of organic pollutants from composting technology for soil remediation. Waste Manag. 2018, 72, 138–149.
  5. Martin, C.C.S.; Brathwaite, R.A. Compost and compost tea: Principles and prospects as substrates and soil-borne disease management strategies in soil-less vegetable production. Biol. Agric. Hortic. 2012, 28, 1–33.
  6. Kalamdhad, A.S.; Singh, Y.K.; Ali, M.; Khwairakpam, M.; Kazmi, A. Rotary drum composting of vegetable waste and tree leaves. Bioresour. Technol. 2009, 100, 6442–6450.
  7. Belyaeva, O.; Haynes, R. Chemical, microbial and physical properties of manufactured soils produced by co-composting municipal green waste with coal fly ash. Bioresour. Technol. 2009, 100, 5203–5209.
  8. Neklyudov, A.D.; Fedotov, G.N.; Ivankin, A.N. Aerobic processing of organic waste into composts. Appl. Biochem. Microbiol. 2006, 42, 341–353.
  9. Smith, J.L.; Collins, H.P.; Bailey, V.L. The effect of young biochar on soil respiration. Soil Biol. Biochem. 2010, 42, 2345–2347.
  10. Sayara, T.; Basheer-Salimia, R.; Hawamde, F.; Sánchez, A. Recycling of Organic Wastes through Composting: Process Performance and Compost Application in Agriculture. Agronomy 2020, 10, 1838.
  11. Hadar, Y.; Papadopoulou, K.K. Suppressive Composts: Microbial Ecology Links Between Abiotic Environments and Healthy Plants. Annu. Rev. Phytopathol. 2012, 50, 133–153.
  12. Sundberg, C.; Yu, D.; Franke-Whittle, I.; Kauppi, S.; Smårs, S.; Insam, H.; Romantschuk, M.; Jönsson, H. Effects of pH and microbial composition on odour in food waste composting. Waste Manag. 2013, 33, 204–211.
  13. Trupiano, D.; Cocozza, C.; Baronti, S.; Amendola, C.; Vaccari, F.P.; Lustrato, G.; Di Lonardo, S.; Fantasma, F.; Tognetti, R.; Scippa, G.S. The effects of biochar and its combination with compost on lettuce (Lactuca sativa L.) growth, soil properties, and soil microbial activity and abundance. Int. J. Agron. 2017, 2017, 3158207.
  14. Pane, C.; Palese, A.M.; Celano, G.; Zaccardelli, M. Effects of compost tea treatments on productivity of lettuce and kohlrabi systems under organic cropping management. Ital. J. Agron. 2014, 9, 153.
  15. Ventorino, V.; Pascale, A.; Fagnano, M.; Adamo, P.; Faraco, V.; Rocco, C.; Fiorentino, N.; Pepe, O. Soil tillage and compost amendment promote bioremediation and biofertility of polluted area. J. Clean. Prod. 2019, 239, 118087.
  16. Coelho, L.; Osório, J.; Beltrão, J.; Reis, M. Efeito da aplicação de compostos orgânicos no controlo de infestantes na cultura de Stevia rebaudiana e nas propriedades do um solo na região do Mediterrâneo. Rev. Ciências Agrárias 2019, 42, 111–120.
  17. Pane, C.; Spaccini, R.; Piccolo, A.; Celano, G.; Zaccardelli, M. Disease suppressiveness of agricultural greenwaste composts as related to chemical and bio-based properties shaped by different on-farm composting methods. Biol. Control 2019, 137, 104026.
  18. Uyizeye, O.C.; Thiet, R.K.; Knorr, M.A. Effects of community-accessible biochar and compost on diesel-contaminated soil. Bioremediat. J. 2019, 23, 107–117.
  19. Pose-Juan, E.; Igual, J.M.; Sánchez-Martín, M.J.; Rodríguez-Cruz, M.S. Influence of Herbicide Triasulfuron on Soil Microbial Community in an Unamended Soil and a Soil Amended with Organic Residues. Front. Microbiol. 2017, 8, 378.
  20. He, Z.; Yang, X.; Kahn, B.A.; Stoffella, P.J.; Calvert, D.V. Plant nutrition benefits of phosphorus, potassium, calcium, magnesium, and micronutrients from compost utilization. Compost. Util. Hortic. Crop. Syst. 2001, 307–320.
  21. Manirakiza, N.; Şeker, C. Effects of compost and biochar amendments on soil fertility and crop growth in a calcareous soil. J. Plant Nutr. 2020, 43, 3002–3019.
  22. Clay, D.E.; Alverson, R.; Johnson, J.M.; Karlen, D.L.; Clay, S.; Wang, M.Q.; Bruggeman, S.; Westhoff, S. Crop Residue Management Challenges: A Special Issue Overview. Agron. J. 2019, 111, 1–3.
  23. Sarkar, P.; Chourasia, R. Chourasia, Bioconversion of organic solid wastes into biofortified compost using a microbial consortium. Int. J. Recycl. Org. Waste Agric. 2017, 6, 321–334.
  24. Gajalakshmi, S.; Abbasi, S.A. Solid Waste Management by Composting: State of the Art. Crit. Rev. Environ. Sci. Technol. 2008, 38, 311–400.
  25. Huang, W.; Hall, S.J. Elevated moisture stimulates carbon loss from mineral soils by releasing protected organic matter. Nat. Commun. 2017, 8, 1–10.
  26. Ramachandra, T.; Bharath, H.; Kulkarni, G.; Han, S.S. Municipal solid waste: Generation, composition and GHG emissions in Bangalore, India. Renew. Sustain. Energy Rev. 2018, 82, 1122–1136.
  27. Ayilara, M.S.; Olanrewaju, O.S.; Babalola, O.O.; Odeyemi, O. Waste Management through Composting: Challenges and Potentials. Sustainability 2020, 12, 4456.
  28. Glawe, U.; Visvanathan, C.; Alamgir, M. Solid waste management in least developed Asian countries–a comparative analysis. In Proceedings of the International Conference on Integrated Solid Waste Management in Southeast Asian Cities, Siem Reap, Cambodia, 5–7 July 2005.
  29. Sharholy, M.; Ahmad, K.; Mahmood, G.; Trivedi, R.C. Municipal solid waste management in Indian cities—A review. Waste Manag. 2008, 28, 459–467.
  30. Visvanathan, C.; Trankler, J. Municipal solid waste management in Asia: A comparative analysis. In Proceedings of the Workshop on Sustainable Landfill Management, Chennai, India, 3–5 December 2003.
  31. Hussain, M.; Butt, A.R.; Uzma, F.; Ahmed, R.; Irshad, S.; Rehman, A.; Yousaf, B. A comprehensive review of climate change impacts, adaptation, and mitigation on environmental and natural calamities in Pakistan. Environ. Monit. Assess. 2020, 192, 1–20.
  32. Sivaramanan, S. Global Warming and Climate change, causes, impacts and mitigation. Cent. Environ. Auth. 2015, 2, 1–26.
  33. Gunaruwan, T.L.; Gunasekara, W.N. Management of Municipal Solid Waste in Sri Lanka: A Comparative Appraisal of the Economics of Composting. NSBM J. Manag. 2016, 2, 27.
  34. Steen, E.; Brooks, M. Medical Waste Management—A review. J. Environ. Manag. 2015, 163, 98–108.
  35. Manzoor, J.; Sharma, M. Impact of Biomedical Waste on Environment and Human Health. Environ. Claims J. 2019, 31, 311–334.
  36. Patil, P.M.; Mahamuni, P.P.; Shadija, P.G.; Bohara, R.A. Conversion of organic biomedical waste into value added product using green approach. Environ. Sci. Pollut. Res. 2019, 26, 6696–6705.
  37. Dinesh, M.S.; Geetha, K.S.; Vaishmavi, V.; Kale, R.D.; Krishna-Murthy, V. Ecofriendly treatment of biomedical wastes using epigeic earthworms. J. Indian Soc. Hosp. Waste Manag. 2010, 9, 5–20.
  38. Ayuso, M.; Hernández, T.; Garcia, C.; Pascual, J. Stimulation of barley growth and nutrient absorption by humic substances originating from various organic materials. Bioresour. Technol. 1996, 57, 251–257.
  39. Vuorinen, A.H.; Saharinen, M.H. Evolution of microbiological and chemical parameters during manure and straw co-composting in a drum composting system. Agric. Ecosyst. Environ. 1997, 66, 19–29.
  40. Guerra-Rodríguez, E.; Vázquez, M.; Díaz-Raviña, M. Co-composting of barley wastes and solid poultry manure. Bioresour. Technol. 2000, 75, 223–225.
  41. Keeling, A.; McCallum, K.; Beckwith, C. Mature green waste compost enhances growth and nitrogen uptake in wheat (Triticum aestivum L.) and oilseed rape (Brassica napus L.) through the action of water-extractable factors. Bioresour. Technol. 2003, 90, 127–132.
  42. Iranzo, M.; Cañizares, J.V.; Roca-Perez, L.; Sainz-Pardo, I.; Mormeneo, S.; Boluda, R. Characteristics of rice straw and sewage sludge as composting materials in Valencia (Spain). Bioresour. Technol. 2004, 95, 107–112.
  43. Dresbøll, D.B.; Thorup-Kristensen, K. Delayed nutrient application affects mineralisation rate during composting of plant residues. Bioresour. Technol. 2005, 96, 1093–1101.
  44. Gabrielle, B.; Da-Silveira, J.; Houot, S.; Michelin, J. Field-scale modelling of carbon and nitrogen dynamics in soils amended with urban waste composts. Agric. Ecosyst. Environ. 2005, 110, 289–299.
  45. Anto, H.; Trivedi, U.; Patel, K. Glucoamylase production by solid-state fermentation using rice flake manufacturing waste products as substrate. Bioresour. Technol. 2006, 97, 1161–1166.
  46. Zhu, N. Effect of low initial C/N ratio on aerobic composting of swine manure with rice straw. Bioresour. Technol. 2007, 98, 9–13.
  47. Jusoh, M.L.C.; Manaf, L.A.; Latiff, P.A. Composting of rice straw with effective microorganisms (EM) and its influence on compost quality. Iran. J. Environ. Health Sci. Eng. 2013, 10, 17.
  48. Yan, Z.; Song, Z.; Li, D.; Yuan, Y.; Liu, X.; Zheng, T. The effects of initial substrate concentration, C/N ratio, and temperature on solid-state anaerobic digestion from composting rice straw. Bioresour. Technol. 2015, 177, 266–273.
  49. Eklind, Y.; Beck-Friis, B.; Bengtsson, S.; Ejlertsson, J.; Kirchmann, H.; Mathisen, B.; Nordkvist, E.; Sonesson, U.; Svensson, B.H.; Torstensson, L. Chemical characterization of source-separated organic household wastes. Swed. J. Agric. Res. 1997, 27, 167–178.
  50. Kimetu, J.M.; Lehmann, J.; Ngoze, S.O.; Mugendi, D.N.; Kinyangi, J.M.; Riha, S.; Verchot, L.; Recha, J.; Pell, A.N. Reversibility of soil productivity decline with organic matter of differing quality along a degradation gradient. Ecosystems 2008, 11, 726–739.
  51. Larney, F.J.; Olson, A.F.; Miller, J.J.; DeMaere, P.R.; Zvomuya, F.; McAllister, T.A. Physical and chemical changes during composting of wood chip-bedded and straw-bedded beef cattle feedlot manure. J. Environ. Qual. 2008, 37, 725–735.
  52. Yuan, J.-H.; Xu, R.-K.; Qian, W.; Wang, R.-H. Comparison of the ameliorating effects on an acidic ultisol between four crop straws and their biochars. J. Soils Sediments 2011, 11, 741–750.
  53. Zhao, X.-L.; Li, B.-Q.; NI, J.-P.; Xie, D.-T. Effect of four crop straws on transformation of organic matter during sewage sludge composting. J. Integr. Agric. 2016, 15, 232–240.
  54. Abbas, A.; Naveed, M.; Azeem, M.; Yaseen, M.; Ullah, R.; Alamri, S.; Ain Farooq, Q.U.; Siddiqui, M.H. Efficiency of wheat straw biochar in combination with compost and biogas slurry for enhancing nutritional status and productivity of soil and plant. Plants 2020, 9, 1516.
More
ScholarVision Creations