Bod and Cod Characteristics of Effluents from Formic Acid and Sodium Hydroxide Pulping of Kenaf Stem
Chukwudebelu JA1*and Agunwamba JC2
1Federal Institute of Industrial Research, Nigeria
2Department of Civil Engineering, University of Nigeria, Nigeria
Submission: October 07, 2019; Published: October 21, 2019
*Corresponding author: Chukwudebelu JA, Agunwamba JC. Bod and Cod Characteristics of Effluents from Formic Acid and Sodium Hydroxide Pulping of Kenaf Stem. Int J Environ Sci Nat Res. 2019; 22(2): 556081.
How to cite this article: George Ouma Ochola, Daniel Odinde Nyamai, J B Okeyo Owuor . Impacts of Land Use and Land Cover Changes on the Environment associated with the Establishment of Rongo University in Rongo Sub-County, Migori County, Kenya. Int J Environ Sci Nat Res. 2019; 21(5):556072.DOI: 10.19080/IJESNR.2019.22.556081
Abstract
The pulp and paper industry are considered as one of the major potential sources of pollution in the environment. Environmental effects have been attributed to chemicals introduced during the manufacturing process. Here, effluents from two chemical pulping processes were analyzed for Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). A dewatered kenaf stem was cooked in the 20%, 60% & 90% concentrations of formic acid and sodium hydroxide at time intervals of 1hr, 2hrs and 3hrs to compare the COD and BOD of their effluents for environmental friendliness. Analysis of the parameters of the three concentrations at the three time interval and physical examination of the pulp showed that 60% concentration of the acids at 2hrs pulping is better. COD of the effluent from formic acid was 1960mg/L while that of sodium hydroxide gave 7000mg/L. Also, the BOD of formic acid effluent was 31.25mg/L while sodium hydroxide effluent gave 37.5mg/L. It can be concluded here that effluent from pulping kenaf stem with formic acid at 60% concentration for two hours is less polluting than using sodium hydroxide of the same concentration with respect to COD and BOD.
Keywords: Kenaf Effluent Formic acid Sodium hydroxide Chemical oxygen demand Biochemical oxygen demand
Introduction
TReports from literature have shown that industrialization improves the economic value of a nation but simultaneously leads to degradation of the environment [1]. Paper is an essential commodity of today’s society. The pulp and paper industry has been growing with demand of paper. These industries also affect the world economy, because their products are consumed worldwide [2] pointed out that pulp and paper industry has been a major consumer of natural resources (wood, water) and energy (fossil fuels, electricity) and a significant contributor of pollutants discharge to the environment. Pulp and paper industry is considered as one of the most polluting industry contributing 100 million kg of toxic pollutants that are being released every year in the environment according to [3]. Effluent quality is commonly judged on the basis of such aggregate characteristics as biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total solids (TS), turbidity, pH, color etc. Biological oxygen demand is the amount of oxygen required for microbial degradation of organic matter while chemical oxygen demand is the amount of oxygen required to breakdown both organic and inorganic matter. Both are parameters which indicate the pollution load of effluent.
It has previously been observed that pulp and paper industry typically generates large quantities of wastewater and this effluent cause considerable damage to the receiving water body if discharged untreated as they have high BOD, COD and suspended solids [4,5] reported that polluted river due to pulp and paper effluent discharge has adversely affected the aquatic fauna as well as communities in the surrounding areas who economically depend on this river for fishing and agriculture purposes. In addition to the pollution by pulping processes, the continuous use of wood which is raw material for paper making is having a devastating impact both economically and environmentally. In addition to being faced with national paper shortages, Nigerian paper and pulp manufacturing sub-sector of the economy is nonexistent. The few existing ones have not considered environmental issues in their production processes.
Previous research has established that pulping is the process generally started by debarking, which removes soil,dirt, and barks from the wood raw materials and converts the plant fiber into smaller pieces (chips). The main aim of any pulping procedure consists of a selective extraction of lignin from lignocellulosic like wood and nonwood materials without degradation of cellulose. Chemical pulping achieves fiber separation by dissolving the lignin that cements the fibers together. Among various processes, chemical pulping generates high amount of wastewater. Results from earlier studies shows that waste water generally contains high concentration of color, Biological oxygen demand (BOD) and Chemical oxygen demand (COD) due to the presence of lignin and its derivatives from the raw cellulosic materials, chlorinated compounds, suspended solids, fatty acids, tannins, resin acids, sulfur and its compounds etc., [6,7] reported that organic and inorganic constituents of effluent are responsible for the characteristic dark brown color and toxicity of effluent.
Soda pulp is the original chemical pulp and is produced by cooking chips of (usually) deciduous woods in a solution of caustic soda under pressure. The principle drawback of any conventional pulping process of lignocellulosics is that it is not possible to separate lignin and hemicelluloses without alteration of their chemical structure. During the last few years many attempts have been made to develop organogold processes based on the application of alcohol as reported by [8,9] and organic acid which was reported by Young and [10].
[11] reported that Chemoil’s process is based on acidic delignification to remove lignin, a desired part of the hemicellulose and nutrients, while silicon remains in the pulp. In the process pulping is carried out with formic acid at slightly elevated temperatures with a conventional liquor-to-straw. Resulting wood pieces are cooked at high or low temperature and pressure. Also, chemical techniques can be used to separate lignin and hemicelluloses from cellulose used for making paper.
This process is usually carried out by means of wet processes, which is responsible for removing large amounts of organic compounds from the processing wood [12] This study set out with the aim of comparing the COD and BOD of the effluent obtained from pulping kenaf stem with formic acid and sodium hydroxide. The major area of interest was to determine their environmental friendliness.
Materials and Method
Kenaf stem was chopped into 1 to 4cm long, washed with warm water to remove dirt and dust. The washed kenaf was dewatered to a solid content of 40% to 45%. 5 grams of kenaf stem was taken in 400ml of cooking liquor in 1000ml flask at atmospheric pressure and pulped at 20%, 60% and 90% concentrations of formic acid and sodium hydroxide, cooking time was varied from 1hr, 2hrs & 3hrs at 95oC. At the end of each period, the sample was filtered with a fine mesh sieve to get the effluent used in the analyses. The effluent was analyzed using the Standard Method for Examination of Water and Wastewater [13].
The parameters determined were COD and BOD.
Calculation done to determine the BOD5;
DO1 = initial dissolved
DO5 = final dissolved oxygen (dissolved oxygen after five days)
P = fraction of sample (volume of sample/volume of sample bottle)
Calculation done to determine the COD;
Where Vt is the volume of titrant, N is normality of the standard Ferrous Ammonium Sulphate and Vs is volume of sample used. Chemical Oxygen Demand (COD) represents the amount of oxygen required to oxidize all of the organic matters both degradable and non-degradable present in the sample. Figure 1-4 showed the values of COD and BOD of the effluents when the stem was pulped with 20%, 60% and 90% concentrations of formic acid and sodium hydroxide at 3 hours interval. With sodium hydroxide (NaOH), the COD values in the reaction was at lowest (3050mg/L) after 1 hour but increased with increase in time with a value of 7300mg/L at 3 hours. This showed that degradation increased with time. But, Karimi et al. [14] reported a COD of 1178 mg/L from soda pulping effluents. Formic acid had its lowest COD value (1252mg/L) at 2 hours which did not differ significantly with values at 1 (1332mg/L) and 3 (2000mg/L) hours. BOD (Biochemical Oxygen Demand) represents the amount of oxygen used by microorganism to decompose organic material. The BOD value of NaOH pulping is also lowest after 1hr with 13.75mg/L and this also increased gradually with time to 17.5. This also showed increased degradation with time and the value reported by [14] was 690mg/L for BOD. With formic acid, the effluent has BOD value of 10.63 which increased with increase in time to 30mg/L.
The 60% concentration of FA gave effluent with higher COD of 2800mg/L at 3hrs as compared to 20% which has 2000mg/L at 3hrs. The COD of effluent from 60% concentration of NaOH was high after 1hr (6250mg/L) but rose sharply after 2hrs to 14350mg/L at 3hrs. This showed that both concentration and time has impact on the degradation of the lignin. BOD values of FA effluent at 60% concentration increased minimally with increase in time of heating with maximum value of 34.38mg/L after 3hrs. While the increase in BOD value of effluent from NaOH was very minimal between 1 and 2hrs Figure 5.
At 90% concentration, COD from FA pulping increase with time, having highest and lowest as 3488mg/L (1hr) and 3648mg/L (3hrs). The value from NaOH pulping also has highest and lowest as 5650mg/L (1hr) and 18750mg/L (3hrs). The BOD value of both FA and NaOH followed the same pattern of increasing with time. [15] reported the value of 5.8mg/L for COD during the pulping of kenaf with soda. The highest COD value (18750mg/L) obtained in this research was far below 174680mg/L which was the COD value showed by [16] during soda pulping. The rise in COD value after 2 hours might be due to the presence of more oxidisable organic compounds in the effluent as identified by [17]. With formic acid, the COD values of the effluent increased with increase in concentration of the acid from 20% to 90%. This agrees with results obtained by [18] which reported that COD values increase with increase in formic acid concentration [18-20] have worked on formic acid pulping of agricultural residues but their focus were on the properties of pulp and not on the waste produced during the process Table 1-4
Conclusion
From the physical observation of the pulp samples, 1 hour at 20% concentration of acids was under pulped, 2 hours at 60% concentration was well pulped while the one for 3hours with 90% concentration, was over pulped. Also, analysis showed that 2 hours pulping with 60% concentration of the chemicals has lower COD and BOD. From the results, it showed that effluent from the FA pulped kenaf stem has less pollution load using COD and BOD as a yard stick. If kenaf waste can be turned into useful resource using process that is less harmful to the environment, farmers can reap a second harvest. However, further study with more focus on other effluent parameters is therefore suggested.
Acknowledgement
The support from the Federal Institute of Industrial Research, Oshodi, Lagos, Nigeria and University of Nigeria, Nsukka, during this work is well appreciated
References
- Hossain K, Rao A (2014) Environmental change and its effect. Eur J Sustain Dev 3(2): 89-96.
- Kaizar H, Norli I (2015) Bioremediation and Detoxification of Pulp and Paper Mill Effluent: A Review. Research Journal of Environmental Toxicology 9(3): 113-134.
- Dey S, Choudhury M, Das S (2013) A review on toxicity of paper mill effluent on fish. Bull. Environ. Pharmacol Life Sci 2(3): 17-23.
- Chandra R, Raj A, Purohit H, Kapley A (2007) Characterisation and optimisation of three potential aerobic bacterial strains for kraft lignin degradation from pulp paper waste. Chemosphere 67(4): 839-846.
- Zuby A, Ajay S (2014) Impact of Pulp and Paper Mill Effluent on Water Quality of River Aami and its Effect on Aquatic Life (Fish). Global Journal of Pharmacology 8(2): 140-149.
- Kesalkar V, Isha P, Khedikar, Sudame A (2012) Physico- chemical characteristics of wastewater from Paper Industry. IJERA 2(4): 137-143.
- Chopra A, Pushpendra P (2012) Removal of color, COD and lignin from pulp and paper mill effluent by Phenerochate chrysosporium and Aspergillus fumigates. Journal of Chemical and Pharmaceutical Research 4(10): 4522-4532.
- Lora JH, Aziz J (2000) Organosolv pulping: A Versatile Approach to Wood Refining. Tappi J 68(8): 94-97.
- Lonnberg B, Laxen T, Sjoholm R (1987) Chemical pulping of softwood chips by alcohols, I Am cooking Paperi ja Puu 69: 757-762.
- Parajo JC, Alonso JL, Vazquez D, Santos V (1993) Optimization of catalyzed acetosolv fractionation of pine. Holzforschung 47(3): 188-196.
- Rousu P, Rousu P, Anttila J (2002) Sustainable pulp production from agricultural waste. Resources. Conservation and Recycling 35: 85-103.
- Vepsalainen M, Kivisaari H, Pulliainen M, Oikari A, Sillanpaa M (2011) Removal of toxic pollutants from pulp mill effluents by electrocoagulation. Sep Purif Technol 81(2):141-150.
- APHA, AWWA, WEF (2005) Standard Methods for the Examination of Wastewater. Washington DC 21st ed American Public Health Association.
- Karimi S, Abodolkhani A, Karimi A (2011) Discoloration of soda pulping effluent by advanced oxidation processes. Engineering e-Transaction 6(1): 20-25.
- Leekha V, Thapar S (1991) Experiences in Kenaf Pulping in Thailand, Kenaf Assessment Study, draft report prepared for the Tallahatchie County Board of Supervisors Charleston Mississippi 16.
- Preeti N (2008) Studies on the effluent generated during the pulping process in paper industry. Current World Enviroment. 3(1): 189-193.
- Hybes H (1961) The biology of polluted water. Liver pool, Univ Press Liverpool 46(3): 496.
- Hoang Quoc, Lam, Yves Le Bigot, Michel Delmas, Ge´rard Avigno (2001) Formic acid pulping of rice straw. Industrial Crops and Products 14(1): 65-71.
- Ferrer A, Vega A, Ligero P, Rodriguez A (2011) Pulping of empty fruit bunches (EFB) from the palm oil industry by formic acid. Bioresources 6(4): 4282-4301.
- Jahan MS (2006) Formic Acid Pulping of Bagasse Bangladesh J Sci Ind Res 41(3-4): 245-250.