Waste to Worth
Sustainable Solutions for a Greener
Future
Prepared
by: Kashaf Andleeb
Department of Zoology, COMSATS
University Sahiwal
August 2025
Waste to Worth: Exploring Agro-Industrial
By-Products for Methane Mitigation in Pakistan’s Dairy Sector
Author:
Kashaf Andleeb, MPhil Scholar (Zoology), COMSATS University Sahiwal
■ Why Methane Matters
Methane from ruminant livestock is a potent greenhouse gas with a global warming potential 25 times higher than carbon dioxide (Gerber et al., 2013). In Pakistan, poor feed quality and low efficiency contribute to elevated methane emissions (Hristov et al., 2015). Addressing this challenge is crucial for climate-smart dairy farming.
■■ Agro-Waste: A
Hidden Resource
Each
year, Pakistan generates large amounts of citrus pulp, cottonseed cake,
sugarcane bagasse, guava seed meal, and mustard oil cake. These by-products,
often treated as waste, could instead be transformed into valuable livestock
feed—supporting both sustainability and productivity (Arshad et al., 2020).
■ How By-Products
Reduce Methane
- Citrus Pulp
Citrus pulp provides soluble carbohydrates that promote the formation of propionate rather than acetate in the rumen. This shift diverts hydrogen away from methanogenesis, thereby lowering methane yield. Gerber et al. (2013) reported that diets rich in citrus pulp increased propionate pathways and reduced hydrogen availability, resulting in decreased methane precursors. - Cottonseed Cake
Cottonseed cake contains bioactive compounds such as gossypol, which can influence rumen microbial ecology. According to Arshad et al. (2020), gossypol has shown inhibitory effects on methanogenic archaea, while simultaneously enhancing protein supply and microbial protein synthesis. This dual action both suppresses methane-producing microbes and improves nutrient utilization efficiency. - Sugarcane Bagasse
Sugarcane bagasse is often considered a low-quality roughage due to its high lignin content, but treatment methods can enhance its role as a methane mitigation strategy. Patra (2014) highlighted that alkali- or fungal-treated bagasse improved fiber digestibility, leading to altered volatile fatty acid profiles with reduced methane intensity. This indicates that processing bagasse before inclusion in rations can significantly reduce enteric methane emissions. - Guava Seed Meal and Mustard Oil Cake
Secondary metabolites present in these by-products play a critical role in methane suppression. Jayanegara et al. (2015) demonstrated that plant tannins reduce protozoal populations and directly inhibit methanogenic archaea, which results in significant reductions in methane emissions. Similarly, Ku-Vera et al. (2020) reported that glucosinolates and residual oils in mustard oil cake shift rumen fermentation patterns by decreasing hydrogen availability for methanogenesis and simultaneously improving nitrogen utilization.
■■ Biological
Mechanisms
Plant
compounds such as tannins and saponins suppress methanogenic archaea and
protozoa (Jayanegara et al., 2015). Enhanced propionate formation redirects
hydrogen away from methane production (Gerber et al., 2013). Better feed efficiency
reduces methane intensity per unit of animal product (Hristov et al., 2015).
■ Future Pathways for
Pakistan
Pakistan
requires systematic in-vitro and in-vivo studies to test the role of
agro-wastes. National policies must integrate these sustainable feed options
(Khan et al., 2021). Locally adaptable, cost-effective strategies can
complement global innovations and address methane challenges in the dairy
sector (Rao et al., 2022).
■ Towards a Greener
Future
While
high-tech global strategies such as seaweed supplements and synthetic
inhibitors are promising, they are often costly. Pakistan’s best opportunity
lies in low-cost, community-driven innovations such as agro-waste utilization,
biogas generation, and sustainable feeding practices. By aligning local
solutions with global goals, these strategies can deliver scalable methane
reduction and strengthen food security (Gates, 2021; Breakthrough Energy, 2023;
GMH, 2022; IPCC, 2021)
Figure . Methane emissions from dairy farms: Ruminants are a major source of methane, a greenhouse gas nearly 25 times stronger than CO₂. Dairy production in Pakistan contributes significantly to overall GHG emissions.
|
Author (Year) |
Feed / Strategy |
Region / Species |
Methane Reduction |
|
Kinley et al. (2020) |
s Aparagopsis taxiformis (red
seaweed |
Dairy cattle, Australia |
Up
to 80% |
|
Hristov et al. (2015) |
3-NOP
feed additive |
Dairy
cows, USA |
~30% |
|
Roque et al. (2021) |
Seaweed
supplement |
Beef
cattle, USA |
40–50% |
|
Alemu et al. (2017) |
Oils
& fats in diet |
Dairy
cattle, Canada |
15–20% |
v References
§ Arshad,
M. A., Sohaib, M., Ahmed, Z., Imran, M., Arshad, M. S., & Arif, M. (2020).
Climate change and livestock production: A review of methane mitigation
strategies with special reference to Pakistan. Environmental Science and
Pollution Research, 27(24), 31136–31153.
§ Breakthrough
Energy. (2023). Programs: Agriculture & Methane Reduction. https://www.breakthroughenergy.org
§ Gates,
B. (2021). How to avoid a climate disaster: The solutions we have and the
breakthroughs we need. Alfred A. Knopf.
§ Gerber,
P. J., Hristov, A. N., Henderson, B., Makkar, H., Oh, J., Lee, C., ... &
Tricarico, J. M. (2013). Technical options for the mitigation of direct methane
and nitrous oxide emissions from livestock: A review. Animal, 7(s2), 220–234.
§ Global
Methane Hub (GMH). (2022). About us. https://www.globalmethanehub.org
§ Hristov,
A. N., Oh, J., Giallongo, F., Frederick, T. W., Harper, M. T., Weeks, H. L.,
... & Zimmerman, P. R. (2015). An inhibitor persistently decreased enteric
methane emission from dairy cows with no negative effect on milk production. Proceedings
of the National Academy of Sciences, 112(34), 10663–10668.
§ Intergovernmental
Panel on Climate Change (IPCC). (2021). Climate change 2021: The physical
science basis. Contribution of Working Group I to the Sixth Assessment Report
of the IPCC. Cambridge University Press.
§ Jayanegara,
A., Goel, G., Makkar, H. P. S., & Becker, K. (2015). Reduction in methane
emissions from ruminants by plant secondary metabolites: Effects of polyphenols
and saponins. In Sustainable animal agriculture (pp. 151–163). Elsevier.
§ Khan,
M. A., Ahmad, N., & Iqbal, Z. (2021). Challenges and opportunities for
biogas production from livestock manure in Pakistan. Renewable Energy, 168,
1215–1224.
§ Ku-Vera,
J. C., Jiménez-Ocampo, R., Valencia-Salazar, S. S., Montoya-Flores, M. D.,
Molina-Botero, I. C., Arango, J., ... & Rojas-Downing, M. M. (2020). Role
of secondary plant metabolites on enteric methane mitigation in ruminants.
Frontiers in Veterinary Science, 7, 584.
§ Patra,
A. K. (2014). Trends and projected estimates of GHG emissions from Indian
livestock in comparison with GHG emissions from world and developing countries.
Asian-Australasian Journal of Animal Sciences, 27(4), 592–599.
§ Rao,
A., Ali, S., & Hussain, T. (2022). Addressing methane leakage and storage
challenges in Pakistan’s biogas sector. Energy Policy, 160, 112658.
§ Youth-led Approaches to Vermiculture:
From Waste to Worth
Author:
Kashaf Andleeb, MPhil Scholar (Zoology), COMSATS University Sahiwal
§ Introduction
Rapid urbanization and
intensive agriculture have created a global challenge of organic waste
accumulation. More than 1.3 billion tons of food waste is generated annually, a
significant portion of which ends up in landfills where it decomposes
anaerobically, releasing methane—a greenhouse gas nearly 28 times more potent
than carbon dioxide (Gerber et al., 2013). Traditional disposal practices
therefore not only harm the environment but also waste valuable resources.
In this context, vermiculture emerges
as a biological technology that transforms organic residues into high-value
products through the activity of selected earthworm species. Unlike common soil
worms, composting worms efficiently convert diverse feedstocks into
nutrient-rich vermicompost and liquid biofertilizers. This ‘Waste to Worth’
approach integrates environmental protection with soil health improvement,
while simultaneously opening opportunities for youth entrepreneurship in
sustainable agriculture (Edwards & Arancon, 2004; Sinha et al., 2010).
Positioning youth at the center of this transition is crucial. With targeted training and innovative use of local organic resources, young people can lead low-cost, scalable waste solutions that contribute to climate change mitigation and rural livelihoods. Thus, vermiculture is not only a method of waste management but also a pathway for youth-led green growth.
§ Figure 1. Pathway of
organic waste transformation through vermiculture: diverting waste from methane
emissions toward valuable products such as vermicompost and vermiwash, leading
to improved soil health, crop yield, and youth entrepreneurship.
§ Earthworm Species Used in Vermiculture
Not
all earthworm species are suitable for vermiculture. Common soil-dwelling
earthworms such as Lumbricus terrestris or Pheretima posthuma are deep
burrowers and poor composters. In contrast, specialized epigeic species thrive
on surface organic waste and are highly efficient in decomposition (Domínguez
& Edwards, 2011).
§ Table 1. Comparison of common earthworms
vs vermiculture species.
|
Feature |
Common Earthworms |
Vermiculture Worms |
|
Habitat |
Burrowers, deep soil dwellers |
Surface dwellers, live in waste layers |
|
Feeding |
Soil + limited organic matter |
Directly feed on organic waste |
|
Reproduction |
Slow, seasonal |
Fast, continuous |
|
Waste Conversion |
Low efficiency |
High efficiency |
|
Suitability |
Not suitable |
Highly suitable |
§ Earthworm species
§ Figure 2:Comparison of
composting earthworm species commonly used in vermiculture: Eisenia fetida (red
wigglers), Eudrilus eugeniae (African nightcrawler), Perionyx excavatus (Indian
blue worm), and Lumbricus rubellus.
These species differ in climate suitability, waste conversion efficiency, and
adaptability (Domínguez & Edwards, 2011; Tripathi & Bhardwaj, 2004).
§ Table 2.
Comparison of vermiculture species
|
Species |
Climate Suitability |
Efficiency |
Notes |
|
Eisenia fetida |
Temperate/Subtropical |
High waste conversion |
Best-known, hardy |
|
Eudrilus eugeniae |
Warm humid |
Fast decomposer |
Sensitive to cold |
|
Perionyx excavatus |
Tropical (25–30°C) |
Rapid breeder |
Ideal for South Asia |
|
Lumbricus rubellus |
Cool climates |
Moderate |
Cold tolerant |
§ Vermiculture Methods
Different
vermiculture methods can be adopted depending on scale and resources available.
These include bed, pit, tray/tank, and windrow methods (Garg et al., 2006;
Tripathi & Bhardwaj, 2004).
§ Table
3. Vermiculture methods with
procedures, advantages, and limitations.
|
Method |
Procedure |
Advantages |
Limitations |
|
Bed Method |
Raised bed with soil/sand base, waste +
dung layering, worms added, covered with jute/straw. |
Simple, low-cost, good aeration. |
Requires space, exposed to weather. |
|
Pit Method |
Concrete pit with drainage holes, layered
waste + worms, covered with jute. |
Moisture retained, longer-lasting. |
Poor aeration, risk of anaerobic
conditions. |
|
Tray/Tank Method |
Plastic/cement trays with drainage, layered
feed, stackable. |
Urban-friendly, neat, space saving. |
Limited volume, higher setup cost. |
|
Windrow Method |
Outdoor heaps (3–4 ft wide, 2–3 ft high),
worms inoculated, turned regularly. |
Large-scale, efficient for >500 kg/day. |
Needs large land, weather dependent. |
§ Figure 3. Windrow method of
vermiculture: organic waste is arranged in long rows (3–4 ft wide, 2–3 ft
high), inoculated with earthworms, and periodically turned for aeration and
moisture control. This method is highly suitable for large-scale waste
management (Garg et al., 2006; Karmegam et al., 2021).
§ Tray method of
vermiculture:
§ Figure 4. Tray method of
vermiculture: a multi-layered system with bedding (shredded paper, cardboard),
food waste, and composting worms such as Eisenia fetida. The design includes
aerated lids, air vents, and a liquid collection tray for leachate, making it
efficient for small-scale and household-level composting (Edwards &
Arancon, 2004; Karmegam et al., 2021).
§ Products of Vermiculture
Vermiculture generates three major
outputs that are considered eco-friendly biofertilizers and soil conditioners.
Each product plays a unique role in enhancing soil fertility, crop
productivity, and reducing the need for chemical fertilizers.
§ Vermicompost
(Solid Biofertilizer)
Vermicompost is the stabilized, finely
divided organic material produced by earthworms after digesting organic waste.
It is dark, humus-rich, odorless, and contains balanced macro- and
micronutrients (N, P, K, Ca, Mg, Fe, Zn). Besides nutrients, vermicompost is
enriched with beneficial microorganisms (Azotobacter, phosphate solubilizers,
plant growth-promoting rhizobacteria) that improve nutrient cycling in soils.
Studies have shown that vermicompost improves soil structure, increases
water-holding capacity, and enhances seed germination and plant growth (Atiyeh
et al., 2000; Lazcano & Domínguez, 2011).
Application: Used as a top-dressing or soil
amendment at 2–5 tons/ha; can also be mixed in nursery media for seedlings.
§ Vermiwash
(Liquid Biofertilizer)
Vermiwash is the liquid extract
collected by passing water through worm beds. It contains soluble nutrients,
humic acids, vitamins, enzymes, and hormones (auxins, gibberellins, cytokinins)
released by earthworms and microbes. Unlike compost, it works primarily as a plant growth promoter and biopesticide when used as a foliar spray.
Vermiwash has been shown to enhance disease resistance in crops by inducing
systemic acquired resistance (SAR), while also improving photosynthesis and
chlorophyll content (Ismail, 2005).
Application: Foliar spray at 1:10 dilution,
applied every 10–15 days for cereals, vegetables, and fruit crops.
§ Earthworm
Casts (Soil-like Granules)
Earthworm casts are excreta deposited
on the soil surface or within the bed. They are rich in plant-available
nutrients such as nitrate-nitrogen, exchangeable calcium, magnesium, and
phosphorus. Casts also contain humic substances and microbial colonies that
stimulate root growth and enhance soil aggregation. Research has shown that
earthworm casts improve soil porosity, aeration, and biological activity,
making them a natural soil conditioner (Edwards & Bohlen, 1996).
Application: Casts are directly incorporated into
agricultural soils or used in potting mixtures for horticulture.
§
Figure 5. Major products of vermiculture: (i) Vermicompost – a
nutrient-rich organic fertilizer containing macro- and micronutrients with
beneficial microbes; (ii) Vermiwash – a liquid biofertilizer and plant growth
promoter enriched with enzymes and hormones; and (iii) Earthworm casts –
granular excreta rich in readily available nutrients and humic substances.
Together, these outputs improve soil fertility, crop productivity, and reduce
dependency on synthetic fertilizers (Atiyeh et al., 2000; Lazcano &
Domínguez, 2011; Edwards & Bohlen, 1996)
§ Scales of Vermiculture and Youth Training
Youth
adoption of vermiculture requires understanding scales of operation and
practical training. Scales can vary from household to industrial levels (FAO,
2020; Karmegam et al., 2021).
|
Scale |
Waste Input |
Compost Output |
Best Use |
|
Household |
2–5 kg/day |
1–2 kg compost/week |
Kitchen waste management. |
|
Small Farm |
50–100 kg/day |
30–60 kg compost/week |
Farm waste recycling. |
|
Commercial |
500 kg–1 ton/day |
300–600 kg compost/week |
Industrial-scale waste management. |
§ Training
modules for youth should include:
§ Earthworm
biology and handling,
§ Feedstock
preparation,
§ Bed
and method management (moisture, pH, temperature),
§ Monitoring
and troubleshooting,
§ Harvesting
and compost maturity testing,
§ Utilization
and marketing of products (Ndegwa & Thompson, 2001; Karmegam et al., 2021).
§ Environmental and Agricultural Impact
Vermiculture
reduces methane emissions by diverting organic waste from landfills (Patra,
2014). It produces nutrient-rich compost that enhances soil structure, water
retention, and crop yield, while reducing reliance on chemical fertilizers
(Jayanegara et al., 2015; Ku-Vera et al., 2020).
§ Youth Engagement and Circular Economy
Youth
are key drivers of innovation in sustainable agriculture. With proper training
and entrepreneurship support, they can adopt vermiculture practices and
contribute to the circular economy. Programs that encourage youth participation
not only promote climate resilience but also create green jobs (FAO, 2020).
§ Conclusion
Vermiculture
offers an accessible, scalable, and sustainable solution to waste management.
By integrating species-specific knowledge, appropriate methods, and structured
training, youth can lead the transition from waste to worth. With academic and
institutional support, this practice can contribute significantly to achieving
global sustainability goals.
v References
§ Aira,
M., Monroy, F., & Domínguez, J. (2007). Earthworms strongly modify microbial
biomass and activity triggering enzymatic activities during vermicomposting.
Biology and Fertility of Soils
§ Atiyeh,
R. M., Domínguez, J., Subler, S., & Edwards, C. A. (2000). Changes in
biochemical properties of cow manure processed by earthworms (Eisenia andrei)
and their effects on plant growth. Pedobiologia.
§ Domínguez,
J., & Edwards, C. A. (2011). Biology and ecology of earthworm species used
for vermicomposting. Waste Management & Research.
§ Edwards,
C. A., & Arancon, N. Q. (2004). The Science of Vermiculture. CRC Press.
§ FAO
(2020). Youth and Agriculture: Key Challenges and Concrete Solutions. Food and
Agriculture Organization of the UN.
§ Garg,
P., Gupta, A., & Satya, S. (2006). Vermicomposting of different types of waste
using Eisenia fetida: A comparative study. Bioresource Technology.
§ Gerber,
P., et al. (2013). Tackling climate change through livestock. FAO.
Jayanegara, A., et al. (2015). Tannins in ruminant nutrition: Impacts on
methane emissions. Animal Feed Science and Technology.
Karmegam, N., et al. (2021). Vermicomposting fo
Accepted by Dr Handa-Corrigan, Sept 2025