Bleaching Wastewater Research Articles

Biotreatability test of bleach wastewaters from pulp and paper mills

Research is focused on an integrated way to simultaneously optimize the bleaching operations and subsequent wastewater treatment for pulp and paper mills. Bleach wastewaters from ClO2-bleached pulping studies at Institute of Paper Science and Technology (IPST) were used as the feed for batch reactors to test and rank the treatability and kinetics. The key aspect of the system is the use of sequential anaerobic/aerobic phases to enhance reductive dehalogenation of chloro-organic materials. Two continuous reactor systems, one operated in an anaerobic-aerobic mode and a second in an aerobic-aerobic mode, received bleaching wastewater obtained from a full-scale plant. Acclimated cultures from both continuous reactors were used to quantify the AOX (Adsorbable Organic Halide) and COD removal from various bleaching wastewaters. In general, the sequential anaerobic/aerobic treatment of bleach wastewater can improve both biotreatability and degradation rates.

Biotreatab ility test of bleach wastewaters from pulp and paper mills

Research is focused on an integrated way to simultaneously optimize the bleaching operations and subsequent wastewater treatment for pulp and paper mills. Bleach wastewaters from CI02-bleached pulping studies at Institute of Paper Science and Technology (IPST) were used as the feed for batch reactors to test and rank the treatability and kinetics. The key aspect of the system is the use of sequential anaerobic/aerobic phases to enhance reductive dehalogenation of chloro-organic materials. Two continuous reactor systems, one operated in an anaerobic-aerobic mode and a second in an aerobic-aerobic mode, received bleaching wastewater obtained from a full-scale plant. Acclimated cultures from both continuous reactors were used to quantify the AOX (Adsorbable Organic Halide) and COD removal from various bleaching wastewaters. In general, the sequential anaerobic/aerobic treatment of bleach wastewater can improve both biotreatability and degradation rates.

The Effect of Ozone Oxidation Treatments of Pulp Bleaching Wastewater Containing Refractory Organic Substances.

The Effect of Ozone Oxidation Treatments of Pulp Bleaching Wastewater Containing Refractory Organic Substances.

Anaerobic-aerobic fluidized bed biotreatment of sulphite pulp bleaching effluents-I. Global parameters

Four parallel biological fluidized bed reactor systems-one single aerobic, one single anaerobic and two combined anaerobic-aerobic-have been used to treat sulphite chlorine pulp bleaching wastewater. It has been observed that the AOX removal was limited at 30%, independently of the wastewater dilution, mode of operation and retention time. Only small differences could be observed between the three systems involving an aerobic stage. The single aerobic reactor also gave rather competitive results with those having an additional anaerobic step, whereas the removal in the single anaerobic reactor was less than the three other systems. Only at high loading rates did the anaerobic-aerobic recycle reactor (AAR) perform better than the other systems. Constant NPOC/AOX ratio, before and after treatment, showed that the chlorinated material was degraded to the same extent as the non-chlorinated one. The removal by adsorption to biomass and biomass support material was less than 1 % for AOX.

Mutagenicity of pulp bleaching wastewater depends on bleaching technology (chlorine vs. ozone)

Mutagenicity of pulp bleaching wastewater depends on bleaching technology (chlorine vs. ozone)

Investigation of Anaerobic Removal and Degradation of Organic Chlorine from Kraft Bleaching Wastewaters

A study of anaerobic removal of adsorbable organic halide (AOX) from kraft bleaching wastes has been conducted, using bottle bioassay techniques. The anaerobic cultures were fed either acetate or hydrogen and were able to remove from 40 to 65% of the AOX. The removal mechanism and the role of an adapted anaerobic consortium has been investigated with results indicating some biological removal, but significant amounts of sorption or degradation that does not seem to require microbial activity. Significant inhibition of methanogenic activity has also been found in some of the tests.

Treatability of Bleached Kraft Pulp and Paper Mill Wastewaters in a New Zealand Aerated Lagoon Treatment System

The effectiveness of the two biological treatment systems operating at a New Zealand bleached kraft softwood integrated pulp and paper mill was assessed. The two systems operate in different configurations. Treatment system A, which receives general mill wastewaters and chlorination stage bleaching discharges utilises deep, aerated lagoons and has a 4.5 day retention time. Treatment system B, which receives alkali extraction bleaching wastewaters and foul condensates, uses a lagoon system with a retention time of 45 days. Detailed chemical analyses of the untreated and treated wastewaters were made. Mass balances were calculated for a range of physical parameters and for specific chlorinated and non-chlorinated organic constituents. Significant differences in the treatability of various constituents were found. In particular, while system A was able to reduce levels of AOX by 65%, no significant reduction in AOX occurred in system B. In contrast, system B reduced levels of chloroacetic acids by 84% while system A did not achieve any statistically significant removal of these compounds. The treatability of chlorophenolic compounds also differed. System A was unable to remove chlorophenols and chloroguaiacols while system B did not reduce levels of chlorocatechols. These results confirm that the treatability of bleached kraft pulp and paper mill wastewater constituents is dependent upon the characteristics of the treatment systems and the compositions of the wastewaters.

Dynamic modelling of anaerobic digestion

The anaerobic digestion model presented here considers a two step process. First, acidogenic bacteria convert glucose into acetate then methanogenic bacteria convert this acid into methane and carbon dioxide. The biomass and metabolite production rates are described by distinct relations. Therefore, there is not a direct relationship between the growth and the energy production related to metabolite formation. The inhibitory effects of the unionized acid concentration on growth rate of both bacterial populations and the methane production from acetate were considered separately. The model was tested in batch cultures with two types of organic loads, i.e. pea bleaching wastewaters and a synthetic substrate containing sucrose and organic acid. The model allowed to simulate satisfactorily the methane production under very different operational conditions.

クラフトパルプのオゾン漂白における針葉樹パルプと広葉樹パルプの漂白性

From environmental point of view, the use of ozone as a bleaching agent seems to be favorable. In this paper, unbleached pine and beech kraft pulps with almost the same brightness were bleached to assess the bleachability of softwood and hardwood pulps in ozone bleaching. The results obtained were as follows. 1. The optimum moisture content was about 50% for both pine and beech pulps. 2. Beating time of ozone bleached pulps was reduced by about one half in comparison with unbleached pulps. Maximum strength of pulp sheets was established at less CSF 300 ml.3. Increased brightness per consumed ozone of beech pulps was superior to that of pine, especially in the early stage to middle stage of bleaching time Rates of delignification of beech pulps were almost the same as those of pine. Therefore it was presumed that factors, other than quantity of lignin and rate of delignification, also took part in the difference of increasing the brightness between pine and beech. Reduction of viscosity of bleached pulps was remarkably in both species. 4. Strength properties of pulp sheets of ozone bleached pulps decreased compared with unbleached pulps, and the degree of reduction of pine was larger than that of beech. 5. COD (Mn) pollution of ozone bleaching waste water from pulps over brightness 72% was 3050 g/kg-pulp, and BOD/COD (Mn) ratio was 0.60.8, and those of beech were a little higher than those of pine. Reduction of. COD (Mn) by activated sludge treatment of Ozone bleaching waste water was higher than that of alkaline extraction waste water of chlorine containing bleaching system, and that of beech was higher than that of pine.