Chemistry and the meani least Chemistry in the
O
K, so I can almost hear the cries of what on earth is he on about and who wants to read about chemistry, it is so boring!
Well given that our sector is heavily regulated actually a lot does boil down to needing, at least, a reasonable understanding of chemistry and ideally to know a bit more than the regulator.
Last time I mentioned the slightly tongue in cheek reference, certain offi cers within the EA referred to a skip as a ‘mobile hazardous landfi ll’, but of course the truth is we don’t actually know what’s in a skip until it is tipped out.
T is is the point where a bit of science does come in useful. In reality, to defi ne whether a waste is inert, non- hazardous, stabilised non-reactive hazardous (SNRHW) or hazardous is complex.
Most materials are fairly straightforward to sort into categories (although wood may become more challenging going forward, but that’s for another time). Suffi ce to say that unless an operator is 100% sure wood is clean and untreated, then it needs to only go to WID compliant Biomass or Panel Board outlets.
So, to throw in a few key terms that will be familiar to many but is worth discussing. T e table below shows some of the key determinants to decide if a waste material meets an inert status for landfi ll, based on leachate testing. I have only shown the inert limits for landfi ll purposes, there are higher limits for SNRHW and HAZ. T e leachate testing is designed as the name suggests to determine the leachability of wastes, which is usually a lower rate that a total analysis.
DETERMINAND
Total Organic Carbon (TOC)
Loss on Ignition (LOI) Total BTEX
Total PCB’s (7 congenors) EPH C10 - C40 PAHs
[EPA16 + Coronene] pH
UNITS % %
Mg/Kg Mg/Kg Mg/Kg Mg/Kg
INERT LIMIT (mg/kg) 3
10 6
1
500 100 >6
TOC and LOI are measures of the organic content in the waste. Fundamentally, low TOC and LOI demonstrates the waste has little potential to generate methane gas if deposited in a landfi ll. It also means it has no nutrient value.
UROC & ESA agreed withHMRC and the EA have agreed that if LOI is below 10% then provided the other parameters are acceptable for landfi ll it will be taxed at the lower rate. If it is going to be used for a permitted restoration site then of course there will be no tax payable.
BTEX which is short for Benzene, Toluene, Ethylbenzene, and Xylenes, are chemicals that are of concern for carcinogenic and neurotoxic potential, hence a low limit of just 6mg/kg.
PCB is short for Polychlorinated Biphenyls which are persistent organic pollutants (“POPs”) that can cause severe, long-term impacts on, wildlife, ecosystems and human health hence an even lower limit of just 1mg/kg.
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