Previously, I have asked about the effect of SO4 on the anaerobic digestion of paper mill wastewater and the answers. Since now I know it does effect, I would like to know the range of SO4 concentration in the pulp and paper mill wastewater or the recycled paper mill wastewater.
Not sure about sulphates but "sulphide inhibition" is very serious problem in papermill waste water treatment. .
You will find information in a recent review published in Water Research : Meyer T & Edwards EA (2014) Anaerobic digestion of pulp and paper mill wastewater and sludge. Water Research 65: 321-349.
Read these articles and may help you: www.fao.org/docrep/005/v9933e/v9933e03.htm and www.cm-consult.de/download/wwtp_read_only_2.pdf
You may have some idea about concentration of SO4 from paper mill wastewater.
The most important problem which the pulp and paper industry is facing today is the disposal of tremendous volumes of waste water. This waste water is rich in dissolved solids such as chlorides and sulphates of Na, Ca and varying amounts of suspended organic materials. In addition to these constituents, effluents also contain some trace metals like Hg, Pb, and Cr etc. The effluents are generally alkaline in reaction with high chemical and biological oxygen demands. Thus, the effluents discharge into the water systems make the water unfit for irrigation and potable use and create health hazards. Table 2 gives the concentration of sulfate. More details are available in attached paper.
Definitely yes especially in Kraft pulp mills. The cooking chemicals are NaOH and Na2S. After cooking, sulphur content appears as Na2S and Na2SO4. Then, in the recovery boiler, Na2SO4 is reduced back to Na2S for the recovery of cooking chemical.
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