Bio waste & Regenerative

Bio-Waste AND

INVASIVE PLANTS AS REGENERATIVE

Dr Afshin Moini Ferdowsi

RESOURCES

Following the regenerative approach, it is in our interest not only to reduce our impact but also to contribute to the broader system improvement. The use of hazardous biowaste and invasive plants in construction provides a great opportunity in this sense. These materials are at once widely available, well-performing (when properly selected and utilized for the correct use), and low in the value chain. Invasive plants, for their own nature, are too abundant to be appropriately digested by the ecosystem, and often pose threats to its balance and well-being. Similarly, hazardous biowaste cannot be left to degrade in the environment without a specific and managed process, as it needs to be disposed of appropriately in order to avoid the risk of environmental degradation. Both of these resources then provide a great opportunity to avoid emitting materials, keep a closed loop, leverage local resources, and even remediate environmental damages.

BIO WASTE

Bio-waste generally refers to biologically degradable waste of natural origin, typically from plant or animal sources. It includes materials that can be broken down by microorganisms and returned to the soil or processed into other useful forms like compost, biogas, or bio-based materials.

What Is Typically Considered Bio-Waste? This category includes: food waste, green waste (garden trimmings, leaves, branches, grass), agricultural residues (crop husks, pruning, spoiled harvests), forestry byproducts (sawdust, bark, thinnings), animal manure and slaughterhouse waste, biodegradable items (as plant-based packaging for instance)

Bio-waste does not need to originate from a productive (agricultural or industrial) system. It includes: Non-productive waste, like roadside weeds or invasive species; Productive system residues, like crop trimmings or food processing byproducts. However, in policy or industrial contexts (like EU waste directives), the focus is often on bio-waste from urban, agricultural, and industrial systems due to their predictable volumes and management needs.

Some examples of biowaste, relevant for the construction sector:

1. Straw (wheat, rice, barley)

– widely available agricultural residue, biodegradable and renewable. – Used in straw bale walls, clay-straw composite mixes (torchis), thatching, and natural insulation.

2. Sawdust and untreated wood shavings

– Clean wood waste from carpentry or milling. – Used in particleboard, bio-composites, plasters, insulation, or lightweight bio-concrete.

3. Rice husks

– Light and rich in silica; non-toxic and often underutilized. – Used as thermal insulation or filler in bricks and concrete; also calcined into pozzolanic ash for cement replacement.

4. Coconut husk and coir fibers

– Tough, fibrous outer shell of coconuts; naturally rot-resistant. – Used as natural fiber reinforcement in panels, bricks, and insulation mats.

5. Corn cobs and stalks

– Non-toxic field residues, often discarded or burned. – Ground and used in bio-based bricks, lightweight panels, or as formwork filler.

6. Bamboo processing waste (strips, shavings)

– Leftovers from bamboo construction or furniture production. – Shredded and pressed into boards, panels, or used in rammed-earth and lime mixtures.

7. Fruit and vegetable peels (e.g., orange, banana)

– Non-toxic and biodegradable but often wasted. – Experimental use in bio-resins, foams, or natural plastic substitutes for interior panels.

8. Grape pomace (from wine production)

– Non-hazardous mix of skins, seeds, and stems. – Used in the production of insulating panels, bio-resins, and compressed blocks.

9. Hemp hurds (shiv)

– Woody core of the hemp stalk, left after fiber extraction. – Main ingredient in hempcrete, a popular natural insulation and walling material.

10. Sugarcane bagasse (non-fermented)

– Clean, fibrous waste from raw sugar processing. – Used in compressed boards, paper alternatives, and lightweight panel composites.

11. Papermaking sludge (cellulose-rich)

– Mostly biodegradable fiber waste from recycled paper mills. – Dried and used as filler in bricks, fiberboards, or eco-panels.

What is Hazardous Biowaste?

Hazardous biowaste refers to biologically-derived waste that poses risks to human health, ecosystems, or infrastructure due to its chemical, biological, or physical properties. While it originates from organic materials (plant or animal), it becomes hazardous due to:

• Toxic compounds (e.g., phenols, alcohols, pesticides)
• Pathogens or disease risk (e.g., medical waste)
• High acidity or alkalinity
• Persistent or polluting residues
• Flammability or volatility

Unlike general bio-waste, hazardous biowaste cannot be composted or reused without treatment or containment, but in some cases, it is repurposed (e.g., in construction) once stabilized or transformed.

Some examples of Hazardous Biowaste

Here you can find an extract of hazardous biowaste, relevant for construction use. This list is not comprehensive, as the range and availability of such resources is context-specific and broad.

Bagasse from mezcal/tequila production.  Rich in lignin, cellulose, but also acidic residues, high chemical oxygen demand (COD), and contaminants from fermentation. If untreated, it contaminates soil and water. As we will see in the next inputs, it can be utilized to enhance mechanical properties of earth based elements in construction.

olive oil mill waste (alperujo): Contains phenols and organic acids; phytotoxic and polluting. Can be used as bio-aggregates for plaster.

Coffee pulp and husks. Can produce leachates with high acidity and caffeine, also attracts pests. Can be used as lightweight aggregates after drying.

Tobacco waste.  Contains nicotine and other alkaloids; toxic to humans and aquatic life. When burnt and calcined, the resulting ash can be used as a pozzolanic additive in lime-based mortars or cement.

Palm oil mill effluent (POME). Extremely high in COD and BOD; dangerous to water bodies if released untreated.

Forestry and Plant Processing. Tannin-rich bark or wood waste, can leach toxic compounds into water systems. Latex-rich plant waste. Irritant or allergenic; problematic for direct use.