Taking the measure of dust emissions
Measuring dust is one thing, identifying how much of it is your responsibility is quite another. Felicity Landon reports
Air quality debates in the shipping and ports sector are very much focused on NOX, SOX and CO2 right now. But that doesn’t mean dust emissions have fallen off the radar.
For anyone living near a port, clouds of dust from handling cement, grain, fertiliser, coal and other dry bulks are obviously highly visible. Cars and windows coated with dust make the problem personal.
And what of the ‘invisible’ dust? The size of the smallest particle visible to the human eye is 50 microns. When dust solutions expert Richard Posner gives presentations, he starts
by focusing on PM10 and PM2.5: “Basically these can really damage the lungs; they are small enough to bypass the nasal membrane and get through the lungs, scarring the lungs and preventing the ability to extract oxygen from the air,” he says.
From country to country, the rules and regulations vary and measuring, or isolating, the precise impact of port operations in generating dust can be tricky.
Take Murmansk and the loading of coal for export. The ‘black attack’, as locals call the coal dust, has been a headache in Russia’s Arctic capital for several years, says Anna Kireeva, head of communications at the Murmansk office of Bellona, an environmental NGO.
“In the winter it taints snow banks and ice, creating grey rivers of filth with every thaw. For the rest of the year, the coal paints a black crust on city windows and fouls the air,” she says.
Massive pressure from local people, which included a deluge of letters to the regional ministry of environment, meant that the port had to act, she confirms.
“When it comes to Russia, there are no precise rules about the dust – and what’s even worse is that sometimes it is difficult to understand the source of the dust. In response to the complaints in Murmansk, the ministry of environment ordered research. They found that 50% of the black dust was coal dust but the other 50% was from the boiler houses (providing district heating), which use mazut, very low-quality heavy fuel oil. When you remove the black and greasy coating from the windows, you can’t tell if it is coal or from the heavy oil.”
Murmansk Commercial Seaport is one of the city’s largest employers, so tackling the problem was a lot about social responsibility, says Ms Kireeva. “There are no strict regulations or any maximum permitted level of pollution from such activities as coal loading. That is why in Murmansk the ministry of environment sort of kindly asked and persuaded the company to take some measures to reduce the pollution. There were no tools or means of influence.”
The ‘black attack’ became a real problem for Murmansk about five years ago, when the volume of coal being loaded increased by three to four times. The coal is delivered to the port by train and exported all over the world. “After massive complaints by the citizens, the local authorities had to act. The port started to buy special tools to spray the water on the coal piles. It was not very efficient, but it was something. At the same time, the port started to investigate foreign experience of combating the problem.”
The port is now building specially designed screens to prevent the dust escaping from the industrial area. The 20-metre-high screens, running a distance of 2km, are one of
about 12 projects costing a total US$44m intended to reduce the environmental impact of the port, according to a briefing by the seaport.
“When winter returns, we will definitely see it in the snow whether the pollution is there or not,” says Ms Kireeva. “Meanwhile, the port is building a huge new terminal on the
other side of the bay, which will provide closed coal loading. It doesn’t mean that loading will stop on this side, but they are building a really modern facility.”
Controlling dust from operations at port and terminal facilities has become increasingly important, says Richard Posner, president of Dust Solutions Incorporated (DSI). “We are
seeing an enormous amount of attention being paid to dust and a lot of ports are measuring PM10 and PM2.5,” he says. “These are pretty critical measures at ports and terminals, many of which are less concerned about NOX, SOX and CO2 because they are not producing so much.”
DSI manufactures dust suppression systems for a range of industries, including power generation, mining, mineral processing, aggregate, pulp and paper, wood products, hazardous waste, marine and bulk handling. Its solutions include its Dry Fog System and DustTamer wind fence systems.
DSI has just completed one of the largest wind fence projects in the world, a 27-metre high, 3.5 km long fence for a coal handling facility in Russia, says Mr Posner.
Across the world there is plenty of legislation about controlling dust, he says – but there is not enough enforcement. “People are not enforcing it, or people are getting away with it, or there is not sufficient measuring. In parts of the third world, what we typically see is people paying their fines and effectively paying people off.
“In the first world, they pay their fines and start to implement plans to rectify the situation – but it is a long process. If you start to show that you are doing something about it, often you get away with it.”
DSI is active all over the world and legislation does vary dramatically, says Mr Posner. Absolutely you can measure and monitor dust, he says, but it is difficult to isolate where that dust comes from. “It is all to do with the location of where you are putting the monitors.”
The ideal scenario (but unlikely to be feasible in most cases) would be to shut down operations entirely for week, measure what dust is generated in that week and then restart operations and draw the comparisons.
The main dust generators in bulk operations are material handling using grabs and hoppers, open stacks exposed to the wind, and dust thrown up from the road by trucks – although in the case of ports, at least the roads tend to be paved.
While the pressure is often highest to keep local residents happy, Mr Posner says that employees in the port can be forgotten.
“The easiest way to deal with some of the problem is to wear masks – and it is crazy, this infrequent wearing of masks by stevedores and others. Dust can really be detrimental to the local environment, to neighbours and to employees. A lot of the time ports start to do things when the neighbours start complaining. I don’t think they pay much attention to the fact that it also impacts employees – who are seeing this from day to day.”
Guaranteeing Output Parametres?
Balan Velan, managing director of Scorpio Engineering, based in Bangalore, highlights the difficulties of defining and measuring dust.
“What we are talking about is fugitive dust that escapes when grabs open and deposit a load of dry bulk into a hopper in a port,” he says.
“Norms for dust emissions do exist but only for general dust concentration in the atmosphere, particularly at human height levels. Such norms range from 20ppm to 50ppm (parts per million) but this is for dust levels in ambient air at about ground level. What does not exist is how to measure the dust cloud that forms when grabs open and how to determine how much one can reduce this and, if so, what the reduced level should be.
“The issue here is that one cannot measure the initial dust released, so how does one measure the final remedied dust concentration?”
Containment and dust extraction within the area is the solution to dust problems, says Mr Velan. Scorpio’s Dust Cap modules feature suction filters and dust entrapment technology and are designed to be welded on to the top of existing mobile hoppers. The filters evacuate and filter the dust, releasing clean air to the atmosphere.
“In a recent interaction with a customer, they asked us for dust reduction guarantees. We asked them to tell us what the initial dust concentration was so we could let them know
what we could do. They had no answer. Without an input parameter how does one guarantee an output parameter?”
He concludes: “There is no available data that tells us what the dust levels are at the point of emission of the dust. What can be done is only to offer guarantees of visual dust
reduction so that one does not see such a cloud of dust emanating as the grab opens and dumps the product into the hopper.”
The traditional dust bucket method of measuring dust is ‘pretty crude’ and measures dust fall captured over a month of two, says Mr Velan. “No one can define whether the dust so captured comes from the port operations or from many trucks coming into and out of the port kicking up dust from their tyres.”
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