To provide a contamination inhibitor composition capable of effectively inhibiting pitch contamination on a dry part.

The present invention is a contamination inhibitor composition 1 which is imparted to a dry part D of a paper-making machine, and comprising a film forming agent and a gelling agent, wherein the film forming agent is an emulsion consisting of water, a modified silicone and an emulsifier and the gelling agent is a compound represented by the following formula (1):

##STR00001##

[in the formula (1), R.sup.1 each independently represents a hydrogen atom, a hydroxyl group, a carboxyl group or a hydrocarbon group optionally having a substituent having 1 to 3 carbon atoms, R.sup.2 each independently represents a hydroxyl group or a carboxyl group, R.sup.3 represents a hydrogen atom, a hydroxyl group or a carboxyl group, m is an integer of 1 to 5, and n is an integer of 0 to 5.].

Provided is a method for producing paper and a pitch removal agent that can remove pitch efficiently.

A pitch removal agent having an average polymerization degree of 300 to 2500, a saponification index of 70 to 88 mol % and satisfying, when the absorbance at a wavelength of 490 nm is designated as y (Abs) and the saponification index as x (mol %), the Numerical Formula (A) below is added to a pulp slurry during production of paper using waste paper in the step of deinking the waste paper by floatation and/or a step earlier:

y=0.0297x+b(A) (wherein, 70x88 and 2.80b3.03).

In a process for separating a solid material from a suspension of the solid material in water, an organopolysiloxane polyalkylene oxide copolymer comprising a branched organopolysiloxane structure is added to the suspension of solid material in water and the suspension is drained. The organopolysiloxane polyalkylene oxide copolymer comprising a branched organopolysiloxane structure increases the rate of drainage of the suspension.

The present invention is related to a method to produce a treated condensate substantially free of organic matter by treating the condensate with at least one of physical, chemical, chemical-physical treatment or combinations thereof. Further, it is also provided a method to treat a condensate in a pulp processing fiber line utilizing multiple washing stages having at least a treated condensate circulating in a closed loop, prior to feeding the condensate into the fiber line, the method comprising the steps of: a) identifying the colloidal organic compounds in the condensate; b) subjecting the condensate to at least one chemical, physical, chemical-physical treatment or a combination thereof; and c) reducing contamination of the condensate, feeding it to the last washer stage, or to some other stage of the pulping.