Biohazards associated with waste and waste-related biofuels
19 April 2016
Are we doing enough to protect workers and the public from risks related to exposure to biological agents? Pat Swords examines biofuel waste directives
Biofuel from waste
Author: Pat Swords, BE CEng PPSE FIChemE CEnv, Principal Process and Environment, Health and Safety Consultant, PM Group
At the Hazards XXII conference in 2011, I presented a paper entitled, ‘A review of established European practice in relation to biohazards associated with waste and waste related biofuels’. It is not intended to repeat the content of that detailed paper here, not least as it can downloaded from the Institution of Chemical Engineers’ (IChemE) website (1), but more to provide an introduction to the topic.
Indeed, one of the reasons why I prepared the paper was that while biohazards were a topic for consideration at the annual IChemE Hazards conferences, very little on the subject had actually been presented. This was somewhat surprising, given the havoc that biohazards, such as foot-and-mouth disease (Aphthae epizooticae) and BSE (bovine spongiform encephalopathy), have wreaked in this part of the world in recent years. Indeed, when I actually presented the paper at the conference, as I did at a later environmental conference in China, the reaction was, essentially, ‘How come I’ve never considered this before?’
This then begs the question as to whether one should actually be concerned about this issue. From a legislative perspective, our European occupational safety legislation is built around the Framework Safety Directive 89/391/EEC and its twenty ‘individual’ or ‘daughter’ Directives. Some of those are very familiar, such as in relation to construction sites or chemical agents, but the Directive 200/54/EC ‘on the protection of workers from risks related to exposure to biological agents at work’ is neither well known nor understood.
Germany has a system of Statutory Accident Insurers, which dates back to the second half of the 19th century – the time of Bismarck. Unlike the situation in Ireland, where an adversarial legal process can follow an occupational accident, all occupational accidents and illnesses are paid out of a central fund, in which the premium is based on the risk profile of your employment sector. As a result, not only does it lead to a very co-operative approach in the development of safety guidance and regulations, but it also leads to a detailed set of annual statistics related to recognised cases of occupational diseases, new occupational pensions and even fatalities. Such pensions are only granted when all attempts have been made to rehabilitate the person concerned. This data is reported per individual disease category, such as for ‘diseases caused by organic dust’ and subcategory BK 4201 ‘Exogenic allergic alveolitis’ below:
|BK 4201 ‘Exogenic allergic alveolitis’||1995||2000||2005||2010||2014|
|Recognised cases of occupational disease||18||17||8||12||23|
|New occupational disease pensions||6||11||3||6||13|
|Fatalities due to occupational disease||–||3||3||6||1|
While these are quite significant, it must be put in the context that subcategory 4101 ‘Silicosis’ had in 2014: some 758 recognised cases, 483 pensions and 324 fatalities. Silicosis, the exposure to silica dust from such as mining and sand blasting, and asbestos-related diseases dominated the overall picture.
Exogenic allergis alveolitis
So what is ‘exogenic allergis alveolitis’? Hypersensitivity pneumonitis is an inflammation of the alveoli within the lung caused by hypersensitivity to inhaled organic dusts. It has several common names, such as ‘farmer’s lung’, ‘pigeon-fancier’s lung’ or even ‘hairspray lung’, which provides a clue to its origins. Indeed, as far back as 1700, Italian physician Bernardino Ramazzini recorded how workers handling grain were experiencing an acute reaction after repeated exposure to grain dust. Other physicians also recorded how this condition was associated with mouldy hay.
It is accepted that fundamentally, all moulds and mildews are in the position (after in-breathing of the spores and other fungi-related fractions) to trigger allergic reactions. Medical studies in Germany have shown that about 5% of the population demonstrate a sensitising reaction to moulds and mildew. The presence of this sensitisation raises the risk for the development of allergic symptoms and/or further sensitisation. The fungus Aspergillus fumigatus flourishes in soil, decaying vegetation, foods, dusts and water.
Other fungi, including Penicillium, Candida, Curvularia, and Helminthosporium, can cause an identical illness. In some people, the effects of the allergic reaction combine with the effects of the fungus to damage the airways and lungs. The fungus colonizes the mucus in the airways of people with asthma or cystic fibrosis (both of whom tend to have increased amounts of mucus) and causes recurrent allergic inflammation in the lung. The German Statutory Insurers consider that about 9-15% of asthma cases in adults can be partly due to work-related causes.
The Irish Health and Safety Authority has a good section on its website explaining the legislation on biological agents. In some cases, exposure to biological agents can be intentional, whereby the employee works directly with them, such as in research or manufacturing. Then there is the wider issue of non-specific work, where employees “are not deliberately working with micro-organisms (biological agents) but could, through their work, unintentionally become infected by a pathogen”. After all, biological agents are ubiquitous and some, such as discussed above, are hazardous.
Indeed, those biological agents above can, according to the German Statutory Accident Insurers, be found in the fields of agriculture and horticulture, waste disposal (waste sorting, waste recovery, composting), sewage management (handling sewage sludge), recycling, manufacture and processing of foodstuffs, processing of natural fibres (plant-based and animal-based), storage of grains, construction business (restoration of damaged buildings, cleaning up of moist rooms), wood and paper processing, metal processing (using cutting fluids), archives, libraries and offices with air-conditioning.
Traditionally, waste would have gone in a sealed truck to a landfill or, in more developed western cities, to a municipal incinerator. Now a variety of processing techniques are being utilised to recover fractions of the waste and with regard to disposal of the residual fraction, to maximise its energy recovery potential and minimise the impacts of disposal. This is leading to both an increased potential for generation and release of biological agents and to an increased interaction of human receptors with these biological agents. Of particular relevance in this regard are waste-processing steps associated with the reception and stockpiling of waste, the manual sorting of waste, the biological decay of waste, such as by composting or anaerobic digestion, and the handling of waste by-products.
Biofuel waste directives
The Directive on Biological Agents requires for “any activity likely to involve a risk of exposure to biological agents, the nature, degree and duration of worker’s exposure must be determined in order to make it possible to assess any risk to the workers’ health or safety and to lay down the measures to be taken”. However, this task is more complicated than the equivalent risk assessment one would complete for chemical agents. To a large extent, recognised occupational exposure levels for biological agents do not exist. While this is discussed in greater detail in the IChemE paper, as a rule no effective threshold for effects can be determined for biological agents and as such by maintenance of a designated limit value an impact on health cannot be excluded.
The September 2013 German Technical Regulations on Biological Agents, TRBA 214, is a consolidation of previous regulations on the waste handling sector. It defines the concept of the Technical Control Value (TKW), which is the concentration of the biological agent in the air for a specific occupational activity, or for a particular process or plant type, which can fundamentally be reached with the application of the state of technology. This has been determined in TRBA 214 as 5 x 104 cfu/m3 of breathing air as a summation value for mesophilic moulds and mildew (cfu = colony forming units). For compliance, workers have to be provided with highly effective ventilation of some 1,000 m3/h per sorting position, see below. While in other parts of the plant respiratory Personal Protection Equipment (PPE) and air filtration for vehicular cabins need to be provided.
The health-related impacts on population in the vicinity of such facilities must also be considered. Various measurement results are available from the vicinity of composting plants, such as from the German Federal Environment Agency. These show wide variations from one as high as 106 cfu/m3, to much lower concentrations that impact on sensitised persons (102 cfu/m3) and with regard to Mucous Membrane Irritation (103 cfu/m3). The key aspect is the design of the composting system. With enclosed composting systems micro-organism concentrations elevated above background levels are to be observed out to 200 m, which is extended to 500 m when open composting is used. German regulations (TA Luft) require that composting plants with a throughput of more than 10,000 t/a must be operated as a closed system.
The UK Health and Safety Executive and Environment Agency have also published similar guidance on composting facilities. Meeting these and emerging limit values for biological agents is going to present a considerable challenge to this sector.http://www.engineersjournal.ie/2016/04/19/biofuel-waste-directives/http://www.engineersjournal.ie/wp-content/uploads/2016/04/Biofuel.jpghttp://www.engineersjournal.ie/wp-content/uploads/2016/04/Biofuel-300x300.jpgChembiofuel,waste