Filtration in the Popular Media: Chinese Fear for Soil and Food

The New York Times recently covered the growing awareness of the pollution problems in China that have come with increased industrialization and growth.  The December 2013 article focused on growing concerns about heavy metals, primarily cadmium, spreading into the food chain and water supply.

  • 1/6 of China’s arable land, nearly 50 million acres, suffers from soil pollution
  • 155 batches of rice tested showed high levels of cadmium, 89 were from Hunan province
  • In 2012 Hunan province produced 17 million tons of rice, 16% of national output
  • 41 percent of the nation’s cadmium pollution as measured by presence in industrial waste water was in Hunan province
  • Officials in Hunan have pledged an annual increase in industrial revenue of 18%
  • Results from a national 2010 soil pollution study have remained unreleased

Pure Cadmium (Cd).

The scope and potential implications of such pollution are significant – the need to begin addressing the problems at their source is equally significant.  Identifying when, where and how the pollution escapes so it can be contained is essential to prevent the problem from growing any further.

Pollution Storage

The article talks about Hunan’s drive to increase its use of its material resources.  More mining and more processing of materials will occur.  It isn’t clear if these materials are being released into the environment at this step or if it occurs later on.  In Europe and the US, there are tight regulations as to how waste from mining operations is treated.  Waste ponds must be lined.  Clear efforts to contain dust clouds which may contain hazardous materials are prescribed.  Given the scope of the problem, it is likely there are problems at this part of the supply chain -unfortunately there isn’t much that filtration can do here.

Pollution from Dry Processing & Refining

1-photo (1)As the mining operations continue, cadmium is released from crushing and other environmental activities.  Picture dust covered facilities that transform big rocks into small rocks.  Here, filtration can do a lot to prevent the release of materials into the atmosphere.  Once facilities are encapsulated, air within the space can be treated with dust cartridge filters.  This is an economically attractive method for producers – they make more money by preventing valuable resources from escaping.

Waste Water

Waste water is a trickier problem.  If we’re dealing with process water, it should be economic to convert what was previously waste into revenue.  It isn’t clear what size the problematic cadmium is – smaller sub 0.40 um materials will need ultrafiltration and RO processes to pull them out of the fluid stream, while larger particles should be be able to be removed with conventional filtration and microfiltration.

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