Nova tecnologia de branqueamento de celulose adaptada ao fechamento do circuito de água

Costa, Marcelo Moreira da; Colodette, Jorge Luiz; Landim, Alexandre; Silva, Cláudio; Carvalho, Ana Márcia Macêdo Ladeira

doi:10.1590/s0100-67622006000100016

Cited by 9 publications

(6 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Conforming to Costa et al (2006), after the second bleaching stage, at the closed-cycle, the brightness result was stabilized. This fact indicates that the COD accumulation that occurred after the second stage had no significant effect on this pulp property.…”

Section: Discussionmentioning

confidence: 94%

See 1 more Smart Citation

The Effect of Water Reduction in Kraft Pulp Washing in Ecf Bleaching

2016

View full text Add to dashboard Cite

-The main objective of this work was to study the technical viability of using the cellulose bleaching effluent, at several stages of the process, seeking fresh water reduction in pulp washing, and evaluating its effect on pulp quality. Eucalyptus spp. industrial cellulosic pulp with oxygen was used in this experiment. The same bleaching sequence D(E+P)DP was performed ten times, under the same conditions (temperature, consistency and time). Counter current washing was used in the bleaching stages, and each sequence was carried out with different washing factors: 9, 6, 3, 0 m³ of distilled water/ton of pulp, trying to reach brightness of 92 ± 0,5% ISO. The ten sequences sought to achieve the stability of the effluent organic load, measured by the chemical oxygen demand (COD). Then, the COD results were compared to the brightness ones from the bleached pulp. The evaluated results from the ten sequences and four different washings showed an increasing in COD due to the organic load accumulation, resulting from the reuse of effluent from previous sequences. This COD increasing provided the lower brightness results during the cycles, besides the water reduction, evidencing the necessity of washing between bleaching stages. In this study, the obtained result for the pulp washing up to 3m³/t was tolerable and even recommended. On the other hand, the pulp without any washing (0m³/t), due to the lack of enough brightness, it is commercially unviable.Keywords: Pulp; Bleaching; Eucalyptus.O EFEITO DA REDUÇÃO DE ÁGUA NA LAVAGEM DA POLPA KRAFT NO BRANQUEAMENTO ECF RESUMO -O objetivo principal do presente trabalho foi estudar a viabilidade técnica de se usar o efluente da lavagem do branqueamento da celulose, nas diversas etapas do processo, visando uma redução no consumo de água fresca na lavagem da polpa avaliando seu efeito na qualidade da polpa. Foi utilizada polpa celulósica industrial de Eucalyptus spp. deslignificada com oxigênio. Foi feita a mesma sequência de branqueamento D(E+P)DP dez vezes, nas mesmas condições (temperatura, consistência e tempo). Utilizou-se a lavagem em contra-corrente nos estágios de branqueamento, cada sequência foi feita com um diferente fator de lavagem: 9, 6, 3 e 0 m³ de água destilada por tonelada de polpa, buscando atingir a alvura de 92 ± 0,5% ISO. As dez sequências realizadas foram uma busca da estabilidade da carga orgânica do efluente medida pela DQO e então comparados os resultados da DQO com os resultados da alvura da polpa já branqueada. Os resultados avaliados das dez sequências e nas quatro diferentes lavagens mostrou o aumento da DQO por causa do acúmulo da matéria orgânica decorrente da reutilização dos efluentes das sequências anteriores. Este aumento da DQO fez com que os resultados da alvura baixassem durante os ciclos e também na redução da água de lavagem, provando a necessidade de que haja lavagem entre os estágios de branqueamento. Neste trabalho o resultado da lavagem até 3m³/t de polpa foi tolerável e ainda recomendável, já para a polpa sem lavagem (0m³/t de p...

show abstract

Section: Discussionmentioning

confidence: 94%

“…In the bleaching sector of the pulp mill, among the several stages that constitute the Kraft process, the reuse of water and the preservation or recovery of substances is of great interest, as it is the largest pollutant generator in the liquid effluent (COSTA et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Water Reduction in Kraft Pulp Washing in Ecf Bleaching

2016

View full text Add to dashboard Cite

show abstract

“…, expressed as active chlorine. In addition to reducing chlorine dioxide consumption and providing pulps with a ceiling over 93% ISO brightness level, the washer after the hot acid stage also worked as an option for partially closing the wastewater circuit, in this case considering the filtrate return from the washer to the recausticizing plant (Costa et al, 2006). It was also found that, for pulps with higher brightness levels, there is a greater loss of OD brightness level, but remaining at levels above the reference level, when compared at the same final brightness level.…”

Section: Effect Of Including Additional Washer (5 Stages)mentioning

confidence: 99%

“…This sequence can be interesting as an alternative when bleaching technology adapted to partial bleach plant closure was required due to environmental concerns. As mentioned in the literature (Costa et al, 2006), if this operation mode was running another additional gain should be on balances such as energy savings and sodium hydroxide make-up, as well as water and effluent treatment costs.…”

Section: Specific Bleaching Operating Costmentioning

confidence: 99%

Low environmental impact bleaching sequences for attaining high brightness level with eucalyptus SPP pulp

Costa

Santos²,

García

et al. 2009

Braz. J. Chem. Eng.

View full text Add to dashboard Cite

-The alternatives used for minimizing the usage of chlorine dioxide in bleaching sequences included a hot acid hydrolysis (A hot ) stage, the use of hot chlorine dioxide (D hot ) and ozone stages at medium consistency and high consistency (Z mc and Z hc ), in addition to stages with atmospheric hydrogen peroxide (P) and pressurized hydrogen peroxide (PO). The results were interpreted based on the cost of the chemical products, bleaching process yields and on minimizing the environmental impact of the bleaching process. In spite of some process restrictions, high ISO brightness levels were kept around 90 % brightness. Additionally, the inclusion of stages like acid hydrolysis, pressurized peroxide and ozone in the bleaching sequences provided an increase in operating flexibility, aimed at reducing environmental impact (ECF Light). The D hot (EOP)D(PO) sequence presented lower operating cost for ISO brightness above 92 %. However, this kind of sequence was not allowed for closing the wastewater circuit, even partially. For ISO brightness level around 91%, the A hot Z hc DP sequence presented a lower operating cost than the others.

show abstract

“…Thus, it is postulated that organically bound chlorine may correlate with reversion of standard and ECF bleached Kraft pulps and any measure aimed at minimizing concentration of chlorine based radicals during bleaching should, in principle, decrease pulp tendency to brightness reversion. 22 The objective of this study was to determine the effect of organically bound chlorine on hardwood pulp brightness reversion. In the first part of the study samples of pure eucalyptus and mixtures of maple, birch and cotton pulps were bleached with the D(EP)D and D(EP)DP sequences and tested under same conditions.…”

Section: Introductionmentioning

confidence: 99%

The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

2009

Self Cite

View full text Add to dashboard Cite

Our previous paper showed fragmentary evidence that pulp brightness reversion may be negatively affected by its organically bound chlorine (OX) content. A thorough investigation on eucalyptus kraft pulp led to the conclusion that OX increases reversion of certain pulps but this trend is not universal. Alkaline bleaching stages decrease reversion regardless of pulp OX content. Pulps bleached with high temperature chlorine dioxide revert less than those bleached with conventional chlorine dioxide in sequences ending with a chlorine dioxide stage but similarly in sequences ending with a final peroxide stage. The use of secondary condensate for pulp washing decreases reversion

show abstract

Nova tecnologia de branqueamento de celulose adaptada ao fechamento do circuito de água

Cited by 9 publications

References 1 publication

The Effect of Water Reduction in Kraft Pulp Washing in Ecf Bleaching

The Effect of Water Reduction in Kraft Pulp Washing in Ecf Bleaching

Low environmental impact bleaching sequences for attaining high brightness level with eucalyptus SPP pulp

The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

Contact Info

Product

Resources

About