Bosses of Oxiris Ltd are considering shutting its plant on Common Lane, because of increased competition with Asia.
It is understood that if the proposal – which began a 30-day consultation process on Friday February 29 – goes ahead, most staff would leave at the end of June or July this year, with a small team of about five employees staying on to decommission the plant.


The company has provided jobs for the community for many years, with its various owners including Croda, Shell, Inspec and, most recently, Degussa.
Steve Huckerby, regional organiser with the GMB union, said: "We are in consultations with the company with a view to keeping the plant open.
"It's a worrying time when people are being made redundant because of the competition with China and the Middle East. If the government could do something to protect our industry for this competition we would be in a better position to keep jobs like these in England."


Dick Croft, divisional officer for Unite the Union, said: "I have seen the documentation and have talked to our representatives there who met with the company last Friday. They are dealing with the matter so far and we have given them every support that we possibly can.
"We are taking the steps that are necesary to try and persuade the company to change their mind."
Knottingley Coun Graham Stokes worked at the plant for 28 years when it was known as Midland Yorkshire Tar.
He said: "It is an employer that will be missed as working there provided me and many others with a good standard of living.


"It is the high wage jobs that are difficult to replace. I am sure everyone will be doing all they can to minimise the impact of these job losses.
"In Wakefield we are managing to attract new employers and locally, employers like Scottish and Southern and Lafarge have increased the number of jobs available through the development of an FGD Plant at Ferrybridge Power Station along with an associated factory to produce plasterboard from the SO2 that no longer goes into the atmosphere.
"We will continue to attract more jobs into the district wherever possible."


A spokesman for Arques Industries AG, owners of Oxiris Ltd, said: "On Friday February 29, Oxiris Limited announced that it was entering into 30 days consultation with its workforce which could lead to a possible cessation of business at its Knottingley site.
"The company continues to run as normal, however it must be appreciated that these are difficult and sensitive times for all the Knottingley site employees.
"The management and employee representatives are working together to determine the best solution for all parties concerned."