ABSTRACT
Environmental concerns are becoming important global tasks. Palm oil mill effluent (POME) contains oil and grease and also rich in organic matter in the form of total suspended solids which can increase biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of POME. It is generated in huge quantities during the production of crude palm oil and pollutes land, water and atmosphere if left untreated. The current study mainly focuses on evaluating the efficacy of fungal isolates screened and isolated from POME dump sites in the bioremediation of POME. Five fungal species used in the present study were previously isolated by the author from POME dump sites of Pedavegi palm oil mill industry. Out of these, Emericella nidulans NFCCI 3643 was proven to be an excellent biological agent in reducing the organic load of POME. The organism showed 80.28% reduction in COD, 88.23% in BOD and 87.34% in oil/grease content at their optimal environmental and nutritional conditions. The mixed cultures showed better reduction efficiency as compared to individual pure cultures. The natural inhabitants of POME dump sites showed their lipolytic ability and E. nidulans was found to be an excellent agent in the bioremediation of POME. Fungal isolates in consortium can function better in bioremediating POME than individual pure cultures.
Key words: Palm oil mill effluent (POME), oil and grease, biochemical oxygen demand (BOD), chemical oxygen demand (COD), organic load, Emericella nidulans, bioremediation.
Palm oil mill effluent (POME) is the waste that is being released by the palm oil mills during oil extraction process from palm fruit bunches. In recent years, a lot of attention has been drawn towards environmental hazards that are caused by direct release of industrial effluents without proper treatment. It was estimated that about 1.5 tons of POME were generated for a tone of fresh palm fruit bunches during oil extraction process (Ahmad et al., 2003). POME is a thick brown colored liquid rich in total solids, oil and grease (Poh and Chong, 2008; Mahzad et al., 2009). The chemical oxygen demand (COD) and biological oxygen demand (BOD) of POME is also high
(Pogaku and Sarbatly, 2013). A high concentration of organic matter, COD (45,000 to 65,000 mg/L) and BOD (18,000 to 48,000 mg/L) of POME was reported by Chin et al. (1996). Soleimaninanadegani and Manshad (2014) reported a COD and BOD in the range of 80,100 to 95,000 and 23,400 to 52,100 mg/L, respectively. A COD and BOD of 40,000 to 50, 000 and 20,000 to 25,000 mg/L were reported by Najafpour et al. (2006). In addition to oil and grease, POME also contains various complex polymers like carbohydrates, lipids, proteins, certain minerals and nitrogenous compounds (Ohimain et al., 2013a). Discharge of untreated POME into aquatic bodies can cause dark coloration of water, eutrophication which further makes the water unsuitable for consumption (Tubonimi et al., 2007; Cheng et al., 2010; Foo and Hameed, 2010). The nature of POME also causes odour pollution (Er et al., 2011). A high COD value of POME also distracts the aquatic life (Maygaonkar et al., 2012), resulting in loss of biodiversity (Singh and Pandey, 2009). As direct discharge of such effluents into the environment without proper treatment might cause considerable environmental problems (Cheng et al., 2010; Awotoye et al., 2011; Jameel and Olanrewaju, 2011; Lam and Lee, 2011), there is need to treat POME from palm oil mills before they are discharged into the environment.
In addition, the high level of organic matter of POME as indicated by its high COD, BOD, grease and oil content, serves as good substrate for growth of a wide variety of microbes (Roux-Van Der Merwe et al., 2005; Md Din et al., 2006). POME being rich in oil content also serves as a habitat for several groups of lipase producing microorganisms as well as hydrocarbon degraders (Rahman et al., 2007; Ohimain et al., 2013b). Use of fungi in the bioremediation of POME has drawn the attention of researchers since last two decades, as most of the previous works involved the use of bacteria in the bioremediation of POME. Several fungi like Rhizopus, Mucor, Candida rugosa, Geotrichum candidum, Aspergillus, etc. have been well studied for their ability to produce lipolytic enzymes (Burkert et al., 2004; D’Annibale et al., 2006; Grbavcic et al., 2007; Nwauche and Ogbonna, 2011). Though, POME is a major environmental concern, only limited studies were reported its bioremediation (Oswal et al., 2002; Wu et al., 2010; Soleimaninanadegani and Manshad, 2014). Therefore, screening and isolation of fungi from POME dump sites provides an alternative way to clean up environmental pollutants as these microbes use the organic compounds present in the POME as supplements and thereby degrade these substances into simpler compounds like methane, carbon dioxide and water. The bioconversion of POME by microorganisms also has additional advantages in that, it makes the POME to be useful in the production of a variety of compounds such as antibiotics, biofertilizer, solvent, bio-insecticides, biohydrogen, polyhydroxyalkanoates, organic acids and enzymes (Wu et al., 2009). Hence, the present study was carried out to investigate the ability of the selected indigenous fungi in the bioremediation of POME.
The results obtained in the present study clearly demonstrate that POME dump sites are potential sources of lipase producing microorganisms and can be used to treat POME.
Collection and preservation of POME
POME was collected from Pedavegi palm oil mill in sterile plastic bottles, sealed and transported in ice box to the laboratory. The sample was stored at -20°C until further use. The physico-chemical characteristics of the POME were studied using the standard methods published by APHA (American Public Health Association, 2005).
Characterization of POME and analytical methods
POME collected from Pedavegi palm oil industry was characterized by determining the physicochemical parameters such as chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), oil and grease (O&G) and pH. The treatment efficiency was determined by characterizing the POME before and after the treatment. Reduction in organic load COD was determined spectrophotometrically, BOD5 was used to measure the biodegradability, TSS were determined as dry weight (mg/L), partition-gravimetric method (Kirschman and Pomeroy, 1949) was employed to determine oil and grease content and pH meter was used to measure the pH. The above methods were carried out as per the standard procedures described in the Standard Methods for the Examination of Water and Wastewater (Clesceri et al., 1999; APHA, 1995, 2005).
Reduction efficiency (RE %) of COD was defined as the amount of COD that decreased as compared to the initial COD amount. Reduction efficiency (RE %) of BOD in terms of BOD5 was defined as the amount of BOD that decreased as compared to the initial BOD amount. The experiments were carried out in triplicates.
Fungal isolates
Five fungal species out of 12 isolates that were screened and isolated from the POME dump sites of Peda vegi palm oil mill, West Godavari District, A.P., India (Suseela et al., 2014) were selected for POME inoculation. They include Emericella nidulans NFCCI 3643, Trichoderma reesei, Trichoderma harzianum, Aspergillus niger and Aspergillus fumigatus. The fungi used for POME inoculation were identified based on morphological characteristics and microscopic observation of fungal spores using lactophenol cotton blue staining. For morphological characterization, the fungal isolates were cultivated on czepakdox agar medium. The shape, size, arrangement and development of conidiophores, phialides and conidiospores were studied using the taxonomic tools of Hoog et al. (2000).
Inoculation of sterile POME
The five fungal isolates that showed highest lipase producing activity were selected in the present study to test their applicability in the bioremediation of POME. The raw POME sample transferred into 250 mL of Erlenmeyer flask was autoclaved at 121°C for 20 min. The cooled autoclaved sample was inoculated with five percent of spore suspension containing 106 cells/mL and incubated at 30°C with shaking at 150 rpm. At an interval of 24 h, samples were collected under aseptic conditions up to 5 days and analyzed for BOD5, COD, oil and grease. Control flasks were not inoculated. The efficiency for organic load reduction and the percentage reduction was measured by using the following equation (Piro et al., 2011):
Where Craw POME is the concentration of COD, BOD5, oil and grease of raw POME and Cf is the concentration of the above said parameters after treatment. All the experiments were performed in triplicates.
Similar experiments were also carried out using mixed cultures of organisms (MC1 (E. nidulans + A. niger + A. fumigatus) and MC2 (T. harzianum + T. reesei)) to test whether the organisms in group can perform better as compared to individual pure cultures. For preparing mixed cultures, spores of all fungi were mixed in equal ratio and inoculated into sterile POME.
Characteristics of POME
POME collected from the Pedavegi palm oil mill was a thick dark brown colored viscous oily liquid with abhorrent odour. The raw POME contains a BOD of 39,476 mg/L, COD at a concentration of 79,980 mg/L, TSS 15,238 mg/L, oil and grease 209 mg/L and pH 4.28. Similar findings were reported by Najafpour et al. (2006), Vijayaraghavan et al. (2007), AbdulKarim et al. (2011), Lam and Lee (2011) and Bala et al. (2015).
Fungal isolates from POME dump sites
A total of 12 different fungal members were screened and isolated from POME dump sites (Suseela et al., 2014). Out of them, 5 fungal isolates that showed good lipase producing activity were selected for further studies.
Oil and grease removal (%) from POME using selected fungal isolates
The use of fungi and yeast such as Trichoderma viride, Saccharomyces cerevisiae and Yarrowia lipolytica for the treatment of POME has not been extended to the removal of oil and grease (Jameel and Olanrewaju, 2011) despite their high potential in removing COD from POME. This may be due to the fact that these microorganisms are not indigenous to POME. In the present study, the ability of 5 fungal members isolated from POME dump sites were investigated for the removal of oil and grease from POME.
The removal (%) of oil and grease from POME is shown in Figure 1. From the results, it is evident that reduction efficiency of Emericella nidulans was highest with 87.34% followed by A. niger, T. harzianum, A. fumigatus and T. reesei with 71.23, 68.21, 61.17 and 59.09%, respectively. There was only 16.85% reduction efficiency with the control indicating the potentiality of our POME isolates in the removal of oil and grease. The results obtained are in agreement with the reports of Oswal et al. (2002) in his work on treatment of POME with Y. lipolytica NCIM 3589. A 93.3% reduction in oil and grease was reported by Lan et al. (2009) using Y. lipolytica W29.
Reduction efficiency (RE %) of COD using selected fungal isolates (Individual pure cultures)
Figure 2 shows the reduction efficiency of COD for selected fungal isolates. From the results, it is evident that reduction efficiency of E. nidulans was highest with 80.28% followed by A. niger, T. harzianum, A. fumigatus and T. reesei with 71.08, 64.83, 61.86 and 59.26%, respectively.
There was only 13.88% reduction efficiency with control indicating that the POME isolates are effective in COD reduction. Similar findings were reported regarding COD reduction by El-Bestawy et al. (2005), Takeno et al. (2005), Lan et al. (2009) AbdulKarim et al. (2011), Abass et al. (2012), Mohammed et al. (2014), Soleimaninanadegani and Manshad (2014) and Bala et al. (2015) in their studies using different microorganisms. The present study is significant in understanding the role of fungi in the bioremediation of oil contaminated effluents such as POME.
Reduction efficiency (RE %) of COD using mixed cultures (combination of fungal isolates)
The reduction efficiency of COD by mixed cultures is shown in Figure 3. From the results, it is clearly evident that there is enhanced organic load reduction with mixed cultures as compared to pure cultures and is as follows: MC1 (E. nidulans + A. niger + A. fumigatus) (91.43%) ˃ MC2 (T. harzianum + T. reesei) (73.14%) ˃ control (17.23%).
This study provides an understanding on the role of mixed cultures in the treatment of waste waters such as those from oil processing industries. The results reported are in good agreement with the results of previous workers who also used mixed cultures for the effluent treatment (Chigusa et al., 1996; Wakelin and Forster, 1997; AbdulKarim et al., 2011).
Enhanced organic load reduction with mixed cultures was also reported by various workers (El-masry et al., 2004; El-Bestawy et al., 2005). The microorganisms in the mixed cultures utilizes the organic substances of POME as nutrients and hence results in organic load reduction (Jameel and Olanrewaju, 2011; Jameel et al., 2011).
Reduction efficiency (RE %) of BOD using selected fungal isolates (individual pure cultures)
Figure 4 represents the reduction efficiency of BOD for selected fungal isolates. From the results, it is evident that reduction efficiency of E. nidulans was highest with 88.23% followed by A. niger, T. reesei, A. fumigatus and T. harzianum with 77.64, 68.17, 63.26 and 52.63%, respectively. Similar findings were reported by El-Masry et al. (2004) and El-Bestawy et al. (2005).
Reduction efficiency (RE %) of BOD using mixed cultures (combination of fungal isolates)
The reduction efficiency of BOD by mixed cultures is shown in Figure 5. From the results, it is clearly evident that there is enhanced organic load reduction with mixed cultures as compared to pure cultures and it is as follows: MC1 (E. nidulans + A. niger + A. fumigatus) (94.34%) ˃ MC2 (T. harzianum + T. reesei) (78.21%) ˃ control (16.54%).
The findings are in agreement with Qingwei et al. (1998) and Bala et al. (2015). The results are mainly attributed to the synergistic effect of different fungal members in the mixed culture (Chigusa et al., 1996; Benka-coker and Ekundayo, 1997; Odegaar et al., 1998). The present treatment process also has advantage in that no additional physical or chemical treatment was required. Similar findings were reported by El-Bestawy et al. (2005) in his work on treatment of contaminated industrial effluents by mixed cultures of bacteria.
The application of isolated fungi in the biodegradation of POME was investigated in the present study. The 5 fungal members isolated from POME dump sites were found to be effective in reducing COD, BOD, oil and grease of POME. This study is certainly useful in understanding the role of fungal members in either pure cultures or in the form of mixed cultures and in biological treatment of effluents from oil processing industries. The mixed culture (MC1) (E. nidulans + A. niger + A. fumigatus) is found to be most effective in the treatment of POME with a reduction efficiency of COD (91.43%) and BOD (94.34%). As high BOD and COD concentrations of POME make it unsuitable for discharge into the environment, recycling of POME by biological treatment will certainly gain importance based on its safe discharge and reuse.
The authors have not declared any conflict of interests.
REFERENCES
|
Abass AO, Jameel TA, Muyibi AS, Abdul Karim IM, Alam MdZ (2012). Investigation of the viability of selected microorganisms on the biodegradation of palm oil mill effluents (POME). International Journal of Environmental Science and Technology 3(3):182-186.
|
|
|
|
AbdulKarim MI, Daud NA, Alam MDZ (2011). Treatment of palm oil mill effluent using microorganisms. In: Alam MDZ, Jameel AT, Amid A (eds) Current research and development in biotechnology engineering at International Islamic University Malaysia (IIUM), 3rd edn. IIUM Press, Kuala Lumpur pp. 269-275.
|
|
|
|
|
Ahmad AL, Ismail S, Bhatia (2003). Water recycling from palm oil mill effluent (POME) using membrane technology. Desalination 157(1-3):87-95.
Crossref
|
|
|
|
|
American Public Health Association (APHA) (1995). In: Standard methods for the examination of water and wastewater. American water works association and water pollution control federation. APHA, Washington DC.
|
|
|
|
|
American Public Health Association (APHA) (2005). Standard methods for the examination of water and wastewater in 21st edn. American Public Health Association (APHA), Washington.
|
|
|
|
|
Awotoye OO, Dada AC, Arawomo GAO (2011). Impact of Palm Oil Processing Effluent Discharging on the Quality of Receiving Soil and Rivers in South Western Nigeria. Journal of Applied Sciences Research 7(2):111-118.
|
|
|
|
|
Bala JD, Lalung J, Ismail N (2015). Studies on the reduction of organic load from palm oil mill effluent (POME) by bacterial strains. International Journal of Recycling of Organic Waste in Agriculture 4:1-10.
Crossref
|
|
|
|
|
Benka-coker MO, Ekundayo JA (1997). Applicability of evaluating the ability of microbes isolated from an oil spill site to degrade oil. Environmental Monitoring and Assessment 45:259-272.
Crossref
|
|
|
|
|
Burkert JFM, Maugeri F, Rodrigues MI (2004). Optimization of extracellular lipase production by Geotrichum sp. using factorial design. Bioresource Technology 91:77-84.
Crossref
|
|
|
|
|
Cheng J, Zhu X, Ni J, Borthwick A (2010). Palm oil mill effluent treatment using a two-stage microbial fuel cells system integrated with immobilized biological aerated filters. Bioresource Technology 101(8):2729-2734.
Crossref
|
|
|
|
|
Chigusa S, Hasegawa T, Yamamoto N, Watanabe Y (1996). Treatment of waste-Chappe water from oil manufacturing plant by yeasts. Water Science and Technology 34(11):51-58.
Crossref
|
|
|
|
|
Chin KK, Lee SW, Mohammad HH (1996). A study of palm oil mill effluent treatment using a pond system. Water Science and Technology 34(11):119-123.
Crossref
|
|
|
|
|
Clesceri LS, Greenberg CG, Eaton AD (1999). Standard Method for the Examination of Water and Wastewater. 20th edn. USA: American Public Health Association (APHA).
|
|
|
|
|
D'Annibale A, Sermanni GG, Federici F, Petruccioli M (2006). Olive-oil wastewaters: A promising substrate for microbial lipase production. Bioresource Technology 97:1828-1833.
Crossref
|
|
|
|
|
El-Bestawy E, El-Masry MH, El-Adl NE (2005). The potentiality of free Gram-negative bacteria for removing oil and grease from contaminated industrial effluents. World Journal of Microbiology and Biotechnology 21(6-7):815-822.
Crossref
|
|
|
|
|
El-Masry MH, El-Bestawy E, El-Adl NI (2004). Bioremediation of vegetable oil and grease from polluted wastewater using a sand biofilm system. World Journal of Microbiology and Biotechnology 20(6):551-557.
Crossref
|
|
|
|
|
Er AC, Nor Abd RM, Rostam K (2011). Palm oil milling wastes and sustainable development. American Journal of Applied Sciences 8(5):436-440.
Crossref
|
|
|
|
|
Foo KY, Hameed BH (2010). Insight into the applications of palm oil mill effluent: a renewable utilization of the industrial agricultural waste. Renewable and Sustainable Energy Reviews 14(5):1445-1452.
Crossref
|
|
|
|
|
Grbavcic SZ, Dimitrijevic-Brankovic SI, Bezbradica DI, Siler-Marinkovic SS, Knezevic ZD (2007). Effect of fermentation conditions on lipase production by Candida utilis. Journal of the Serbian Chemical Society 72(8-9):757-765.
Crossref
|
|
|
|
|
Hoog GS, Guarro J (2000). Explanatory chapters and keys to the genera, In Hoog GS, Guarro J, Gene J, Figueras MJ (eds.), Atlas of Clinical Fungi, Centraal bureau voor schimmel cultures, 2nd edn. Spain Press, Netherlands and Universitat Rovira i Virgili pp. 361-1008.
|
|
|
|
|
Jameel AT, Muyibi SA, Olanrewaju AA (2011). Comparative study of bioreactors used for palm oil mill effluent treatment based on chemical oxygen removal efficiencies. In: Alam MDZ, Jameel AT, Amid A (eds) Current research and development in biotechnology engineering at International Islamic University Malaysia (IIUM), 3rd edn. IIUM Press, Kuala Lumpur pp. 277-284.
|
|
|
|
|
Jameel AT, Olanrewaju AA (2011). Aerobic biodegradation of oil and grease in palm oil mill effluent using consortium of microorganisms. In: Alam MDZ, Jameel AT, Amid A (eds) Current research and development in biotechnology engineering at International Islamic University Malaysia (IIUM), 3rd edn. IIUM Press, Kuala Lumpur pp. 43-51.
|
|
|
|
|
Kirschman HD, Pomeroy R (1949). Determination of oil in oil – field waste waters. Analytical Chemistry 21(7):793-797.
Crossref
|
|
|
|
|
Lam MK, Lee KT (2011). Renewable and sustainable bioenergies production from palm oil mill effluent (POME): win–win strategies toward better environmental protection. Biotechnology Advances 29(1):124-141.
Crossref
|
|
|
|
|
Lan WU, Gang GE, Jinbao WAN (2009). Biodegradation of oil wastewater by free and immobilized Yarrowia lipolytica W29. Journal of Environmental Sciences 21(2):237-242.
Crossref
|
|
|
|
|
Mahzad H, Sa'arib M, Mohamad AMS (2009). Optimization of POME anaerobic pond. European Journal of Scientific Research 32(4):455-459.
|
|
|
|
|
Maygaonkar PA, Wagh PM, Permeswaran U (2012). Biodegradation of distillery effluent by fungi. Bioscience Discovery 3(2):251-258.
|
|
|
|
|
Md Din, MF, Ujang Z, van Loosdrecht MCM, Ahmad A, Sairan MF (2006). Optimization of nitrogen and phosphorus limitation for better biodegradable plastic production and organic removal using single fed-batch mixed cultures and renewable resources. Water Science and Technology 53:15-20.
Crossref
|
|
|
|
|
Mohammed RR, Ketabachi MR, McKay G (2014). Combined magnetic field and adsorption process for treatment of biologically treated palm oil mill effluent (POME). Chemical Engineering Journal 243:31-42.
Crossref
|
|
|
|
|
Najafpour GD, Zinatizadeh A, Mohamed AR, Hasnain Isa M, Nasrollahzadeh H (2006). High-rate anaerobic digestion of palm oil mill effluent in an upflow anaerobic sludge-fixed film bioreactor. Process Biochemistry 41(2):370-379.
Crossref
|
|
|
|
|
Nwauche CO, Ogbonna JC (2011). Isolation of lipase producing fungi from palm oil mill effluent dumpsite at Nsukka. Brazilian Archives of Biology and Technology 54(1):113-116.
Crossref
|
|
|
|
|
Odegaar H, Ruster B, Westrum T (1998). A new moving bed biofilm reactor-application and results. Water Science and Technology 19:157-165.
|
|
|
|
|
Ohimain EI, Izah SC, Jenakumo N (2013a). Physicochemical and Microbial Screening of Palm Oil Mill Effluents for Amylase Production. Greener Journal of Biological Sciences 3(8):307-318.
Crossref
|
|
|
|
|
Ohimain EI, Izah SC, Abah SO (2013b). Air quality impacts of smallholder oil palm processing in Nigeria. Journal of Environmental Protection 4:83-98.
Crossref
|
|
|
|
|
Oswal N, Sarma PM, Zinjarde SS, Pant A (2002). Palm oil mill effluent treatment by a tropical marine yeast. Bioresource Technology 85(1):35-37.
Crossref
|
|
|
|
|
Piro P, Carbone M, Tomei G (2011). Assessing settleability of dry and wet weather flows in an urban area serviced by combined sewer. Water Air and Soil Pollution 214(1-4):107-117.
Crossref
|
|
|
|
|
Pogaku R, Sarbatly RH (2013). Advances in Biofuels. Springer, New York, NY, USA.
Crossref
|
|
|
|
|
Poh PE, Chong MF (2008). Development of anaerobic digestion methods for palm oil mill effluent (POME) treatment. Bioresource Technology pp. 1-9.
|
|
|
|
|
Qingwei L, Mancl KM, Tuovinen OH (1998). Effect of inoculation on the biodegradation of butterfat-detergent mixtures in fixedfilm sand columns. Bioresource Technology 64(1):27-32.
Crossref
|
|
|
|
|
Rahman RNZRA, Leow TC, Salleh AB, Basri M (2007). Geobacillus zalihae sp. nov., a thermophilic lipolytic bacterium isolated from palm oil mill effluent in Malaysia. BMC Microbiology 7(1):77.
Crossref
|
|
|
|
|
Roux-Van Der Merwe MP, Badenhorst J, Britz TJ (2005). Fungal treatment of an edible-oil containing industrial effluent. World Journal of Microbiology and Biotechnology 21:947-953.
Crossref
|
|
|
|
|
Singh NNP, Pandey A (2009). Biotechnology for Agro-Industrial- Residues-Utilisation. Vol. 1, Springer Science + Business Media B.V. New York, NY, USA.
|
|
|
|
|
Soleimaninanadegani M, Manshad S (2014). Enhancement of Biodegradation of Palm Oil Mill Effluents by Local Isolated Microorganisms. International Scholarly Research Notices pp.1-8.
Crossref
|
|
|
|
|
Suseela L, Anupama M, Prudhvilal B, Narasaiah TV, Lavanya Latha JN (2014). Isolation & Characterization of lipase producing fungi from Palm Oil Mill Effluent obtained from Pedavegi, A.P., India. International Journal of Biological and Pharmaceutical Research 5(7):559-565.
|
|
|
|
|
Takeno K, Yamaoka Y, Sasaki K (2005). Treatment of oil-containing sewage wastewater using immobilized photosynthetic bacteria. World Journal of Microbiology and Biotechnology 21:1385-1391.
Crossref
|
|
|
|
|
Tubonimi TKI, Adiukwu PU, Stanley HO, Briggs AO (2007). Impact of Palm oil (Elaeis guineensis Jacq; Banga) Mill Effluent on Water Quality of Receiving Oloya Lake, in Niger Delta, Nigeria. Research Journal of Applied Sciences 2(7):842-845.
|
|
|
|
|
Vijayaraghavan K, Ahmad D, Abdul Aziz ME (2007). Aerobic treatment of palm oil mill effluent. Journal of Environmental Management 82(1):24-31.
Crossref
|
|
|
|
|
Wakelin NG, Forster CF (1997). An investigation into microbial removal of fats, oils and greases. Bioresource Technology 59:37-43.
Crossref
|
|
|
|
|
Wu TY, Mohammad AW, Jahim JM, Anuar N (2009). Optimized reuse and bioconversion from retentate of pre-filtered palm oil mill effluent (POME) into microbial protease by Aspergillus terreus using response surface methodology. Journal of Chemical Technology and Biotechnology 84:1390-1396.
Crossref
|
|
|
|
|
Wu TY, Mohammad AW, Jahim JM, Anuar N (2010). Pollution control technologies for the treatment of palm oil mill effluent (POME) through end-of-pipe processes. Journal of Environmental Management 91:1467-1490.
Crossref
|
|
