Black Liquor Oxidation as a Method for Reducing Air Pollution from Sulfate Pulping

This paper will discuss the sources of odorous air pollutants from sulfate pulping operations. One of the major sources is the recovery furnace. Odors from this source can be reduced considerably by oxidation of the black liquor prior to evaporation and burning. The procedure has been used with considerable success in the northwestern and northeastern parts of the United States. Unfortunately, the majority of sulfate pulp production occurs in areas where southern pine is the basic raw material. For several reasons the black liquor resulting from southern pine operations presents problems when the usual oxidation procedures are used. Although not as effective as normal black liquor oxidation strong black liquor can be oxidized without too much difficulty. Various procedures for oxidation of black liquor will be discussed. Results of stack sampling in U. S. pulp mills with and without the oxidation unit in operation will be reported.     

A New Gas-Liquid Interphase Reactor

A first-order differential equation describes the dynamic response of many continuous air sampling instruments: C_t = C_i + p(dC_i/dt), where C_t is true concentration, C_i is indicated concentration, p is the time constant, and t is time. The time constant, lag time, delay time, and response time are all functions of the volume and flow through the sensor reservoir. All of them can be expressed by the same general equation: t = k₃V/Q, where t is the selected time variable, k₃ is a constant appropriate to the particular system and selected time variable, V is sensor reservoir volume, and Q is the flow rate through the reservoir. The time constant is the time a sampler takes to indicate 63.2 percent of its final response. Select time constants equal to about half of the shortest desired averaging time. Solve the second equation for the reagent flow to give the desired time constant. Selection of such a time constant eliminates spurious “noise” produced by a fast-responding system. It also provides values within 5 percent of true for atmospheres that change markedly between successive intervals. If a slow-responding system must be used, use the first equation to increase apparent response time. A digital computer can be programmed to automatically correct all measured values. Similarly, analog circuitry can be installed in an air sampling instrument to increase or decrease response time. The analog circuitry to increase response time will continuously solve and plot the first equation.     

Glass Fibers and Their Use as Filter Media

Typical air quality effect levels of photochemical oxidants on specific plant substrates are illustrated. These include ambient oxidant exposure data measured as “total oxidant” as well as laboratory exposures to individual pure oxidants, ozone, or PAN compounds, since these oxidants are identified in photochemical smog. New terms, “PaNs” and “PAN-type” oxidant, have been proffered for purposes of clarification of the terminology. PAN-type oxidant more precisely defines the phytotoxicant complex causing silvering or bronzing of the lower leaf surfaces in lieu of the older term “oxidant.” Due to the recognition of several oxidizing phytotoxicants in recent years, it is recommended that the term oxidant be reserved for use as a generic term. A tabular classification of the oxidizing phytotoxicants found in community photochemical smog and the specific syndromes produced is provided.     

Etude comparee de la resistance de trois souches virales en eau de mer et en eau de riviere

The authors made a comparative study of the resistance of three strains of virus, Sabin poliovirus I, Mahoney poliovirus I and réovirus I, in sea-water and in river water, “in vitro” and “in situ” in dialysis bags. The results show the preponderant role of the incubation temperature and the exchanges existing between bags on the resistance of the viral strains. The role of these different factors is discussed.