Waste reduction

The University of Valencia produces tons of very diverse waste yearly. This entails a complex subsequent treatment to reduce its impact on the environment and the economy of the University.

This interactive graph shows the evolution of waste production since the Environment Area was created in 2005. The quantities collected by our centralized systems have increased, reducing the percentage of waste that the production units discarded without recycling. Besides, many producers minimize their waste generation. The weight of collected paper is not shown because its large volume would hide the evolution of the rest of the waste fractions.

The graph in euros shows the results of the effort we make to reduce the cost.

To reduce the quantity and dangerousness of the waste, the priority is:

1. Reduction of the original quantity

To avoid its storage.

It should be bought only the needed quantity. Although it seems that the more reagent quantity is bought it is cheaper, it may be more expensive in the long run If in the end one part is not needed, it may be dangerous while it is stored, besides taking up space. Over time it is easier that it ruins and becomes waste, with its consequent cost of the management.

To reduce de scale.

Both on laboratories for research and for practices, the use of reagents in several grams and litres quantities is not always justified. It is possible to get the same results and give the same lessons by reducing the scale, i.e., using more diluted solutions and in lower volume.

Reduction of dangerousness.

Among several alternatives, people should select the least pollutant. This affects:
 

• The solvents of the reactions.

• The reagents.

• The reactions

• The purification and isolation processes.

Here, it is shown the list of the reagents their least damaging substitutes:

2. Sub products and waste recovery

Recovery avoids new purchases and waste creation. The stored reagents not expected to use are the sort or medium term can be exploited:

• For other uses requiring the same reagent.
• Providing another laboratory using the same reagents (this is available on the Department of Environment, as we know many of the substances used by each laboratory).
• Those substances that have lost the required purity can be exploited for less demanding uses (perhaps in teaching laboratories).
   

3. Recycling.

Recycling makes sense when the recovery process is simple (solvents, glass) or if the reagent price is really high (precious metals). Usually, appreciable quantities are required, and the product can be reused with guarantees.

Mainly in the laboratory practices, and sometimes in research, it is possible to conceive experiments in which the reaction product (or products) can be used as reagents later.

Examples:

• Solvents: distilled them and store them.
• Metal-shaped mercury: suck it up, cover it with calcium polysulfide and recover it.
• Mercury within compounds: dissolve them and convert them in soluble nitrate. Precipitation of sulphides. Recover it.
• Arsenic, bismuth, antimony: dissolve them in HCl and dilute them until appearance of a white precipitate (SbOCl and Bioclim). Add 6M HCl until re-dissolution. Saturate them with hydrogen Filter, wash and dry.
• Selenium, tellurium: dilute it in HCL. Add sodium sulfite to produce SO2 (reducer). Heat (grey selenium and black tellurium black are made). Leave to stand for 12 hours. Filter and dry.
• Lead, cadmium: add HNO3 (nitrates are produced). Evaporate, add water and saturate with H2S. Filter and dry.
• Beryllium: dissolve in 6M HCL, filter. Neutralize (6M NH4OH). Filter and dry.
• Strontium, barium: dissolve in 6M HCL, filter. Neutralize (6M NH4OH). Precipitate (Na2CO3). Filter, wash and dry.
• Vanadium: add to Na2CO3 (layer) in an evaporation plate. Add 6M NH4OH (spraying). Add ice (shaking). Leave to stand for 12 hours. Filter (ammonium vanadate) and dry.
   

4. In situ treatment.

Some simple treatments simplify waste disposal.
The simple mechanical separation of solid waste is the best known example (silica, glass, etc.). But it is also possible to make some simple separations in solutions and mixtures of solvents: distilled solutions containing complex metal or toxic substances.

Furthermore, some simple chemical operations allow completely or partially reduce the danger of certain waste in the same laboratory, such as aqueous solutions or neutralizing heavy metals precipitate.

The main advantages of in situ treatment are:

• Significant economic savings.
• Chemical reduction or elimination of management stages, like the storage, transportation, bureaucracy, etc.
• The producer of waste is usually well prepared technically, and he/she is also informed about the dangers of the generated waste.
• In the following Technical Note of Prevention (NTP) of the National Institute of Workplace Safety and Hygiene (INSHT) a list of treatments is available; NTP 276:

Waste disposal in the laboratory: general processes.

IMPORTANT: WASTE PROCESSING MUST BE EXECUTED UNDER QUALIFIED STAFF RESPONSABILITY, first SAFETY and the ENVIRONMENTAL PROTECTION.

Protocol for sterilization of biological waste. 

5. Delivery to the waste manager.

In our case, this delivery will be made to the authorized manager, and it shall follow the guidelines listed in the laboratory waste disposal programme on this site.

For further ideas, check this guide. ECVET-Lab Best Practices Guide