Investigation on up-flow anaerobic sludge fixed film (UASFF) reactor for treating low-strength bilge water of Caspian Sea ships
© Emadian et al.; licensee BioMed Central. 2015
Received: 9 July 2014
Accepted: 9 March 2015
Published: 20 March 2015
In order to meet the International Maritime Organization (IMO) objectives, the main purpose of this study was using the cheap and practical wastewater treatment system for low-strength bilge water of Caspian Sea ships; therefore, the low-strength bilge water of the Caspian Sea ships has been treated by up-flow anaerobic sludge fixed film (UASFF) reactor at the ambient temperature.
The reactor operated at two hydraulic retention times (HRTs) of 10 h and 8 h. The organic loading rates (OLR) ranged (0.12-0.6) g chemical oxygen demand (COD)/l.day. At the beginning of the experimental procedure, the sludge was immobilized on the surface of the support materials. After 10 days of batch feeding of the reactor with the wastewater as an acclimation period (with COD removal of 59%), the reactor operated continuously. At the end of the experiment, with the HRT of 8 h and OLR of 0.6 g COD/l.day, the COD and total suspended solid (TSS) removal efficiencies reached the amounts of 75% and 99%, respectively. In addition to the good features of the reactor in removing COD and TSS, the effluent oil concentration was significantly lower than the standard value (15 ppm) which has been laid down for the discharge of the bilge water from ships by the IMO.
The obtained data demonstrated that UASFF reactor is an appropriate system for treatment of a low-strength bilge water.
KeywordsAnaerobic treatment UASFF reactor COD pH TSS Oil content
Three kinds of wastewater exist which are produced on ships: black water, grey water and bilge water. Bilge water is the mixture of water, oily fluids, lubricants, cleaning fluids and other similar wastes that accumulate in the lowest part of a ship. The International Maritime Organization (IMO) regulations necessitate that any oil and oil residue discharged in wastewater streams must contain less than 15 mg/l of oil . The common technology is used in ships for treating bilge water is oil water separator (OWS) using the buoyancy difference of oil and water for separation. Cleaning agents in bilge water can create an emulsion of oil in water. When emulsification takes place, buoyancy difference of oil and water is too small to be treated properly via the existing OWS technology.
Other techniques have been studied in order to treat bilge water including membrane technology [2,3], electrocoagulation [4,5], UF/photocatalytic oxidation . Some disadvantages were reported associated with the application of membrane in treatment of bilge water such as: their relatively high cost of production because of the expensive raw materials, fouling which has a number of negative effects such as the reduction in membrane flux, additional capital and maintenance cost due to membrane replacement and regeneration [2,7]. Karakulski et al. reported a promising usage of laboratory-scale ultrafiltration pilot plant with tubular membranes for the treatment of bilge water. However, the use of additional photocatalytic oxidation stage was necessary to eliminate the residual oil . Rincon et al. concluded that the electrocoagulation process was an effective method in destabilization of oil in water emulsions and removing of heavy metals. However, the electricity consumption and the use of additional flotation method should be considered for improving the treatment efficiency .
Anaerobic treatment is a well-established technology for treatment of wastes and wastewaters because it is technologically simple for low energy consumption and it is an efficient, economical and environmentally-friendly method. The final product of anaerobic digestion is biogas which is a mixture of methane and carbon dioxide. These produced components can be applied for heating and upgrading natural gas quality or co-generation . One of the most notable developments in anaerobic treatment process technology is the up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor has some positive features, such as short hydraulic retention time that allows high organic loadings. Furthermore, it has a low energy demand and area requirement [9,10]. A major problem of UASB reactor is the long period (several months) required for the formation of granule sludge in the reactor . Although formation of granule in UASB reactors has some advantages, successful treatment of wastewaters with flocculent sludge UASB reactors have been reported [12,13]. The up-flow anaerobic sludge fixed film (UASFF) reactor configuration has combined the advantages of both UASB and Up-flow anaerobic fixed film (UAFF) reactors. This kind of reactor is efficient in the treatment of dilute to high strength wastewaters at low to high Organic Loading Rates [14,15]. The packing medium in the hybrid reactor plays an important role in giving a better performance to the UASB reactor such as increasing solids retention by dampening short circuiting, improving gas/liquid/solid separation, and providing surface for biomass attachment.
Bilge water is classified as the low strength group of wastewater . Although anaerobic process is used for the treatment of medium and high strength wastewaters, it has already been applied successfully for a number of waste streams including low strength wastewaters [16-18].
In this study, the efficiency of UASFF reactor (on the basis of COD, TSS, oil removal and biogas production) has been studied in treatment of low-strength bilge water under different low organic loading rates at the ambient temperature.
characteristics of pre-settled bilge water; TN and TP were measured in COD = 50 mg/l
8 – 9
20 – 200
800 – 2400
220 – 1760
Inoculum (seed sludge)
The reactor was seeded with a mixture of activated sludge from the aerobic wastewater treatment of the Mazandaran pulp and paper industry and a non-granular sludge obtained from an up-flow anaerobic sludge blanket reactor operating with cheese whey wastewater from the Gela food industry of Amol, Mazandaran, Iran. The TSS of the mixture was 13 g/l. The non-granular sludge was methanogenically active as the biogas bubbles were apparently observed stripping from the sample surface which was collected in a closed bottle.
Several monitoring parameters were evaluated during the entire operation, including COD, TSS and oil concentrations, as well as pH, temperature and biogas production volume rate. For COD analysis, HACH’s Method 8000, a combination of reactor digestion method and colorimetric method, was used . This method is equivalent to standard method 5220D: closed reflux, colorimetric method . Analytical determination of TSS was carried out in agreement with the standard methods for the examination of water and wastewater . Analysis of oil was determined according to USEPA Method 1664, N-Hexane gravimetric method. Temperature and pH were measured using a pH/temperature probe (HANNA, PH212, Germany) with automatic temperature compensation. The method used in pH measurement was generally in compliance with standard method 4500B . Biogas was collected by water displacement and the volume was read from a calibrated gas collection cylinder.
Start-up and operation scheme
Start-up period usually takes a long time. In order to decrease this time, the immobilization of biomass on the support material was done. So, the mentioned mixture of sludge was used by means of a technique described by Zaiat et al. . The support material in combination with the sludge was stored in 1.5 l closed bottle and homogenized for the period of a week by using a shaker so as to secure steadier immobilization of bio-particles in the supporting material. It is noticeable that this initial immobilization of biomass in the support materials has never been done by the other authors. After this stage, the packing material was filled in its place in the UASFF reactor.
The reactor was inoculated with 500 ml of the same sludge mixture. In order to acclimatize the sludge with bilge water, the reactor was daily batch feed with the bilge water (50 mg/l) for 10 days. After each feed, the liquid content of the reactor was continuously circulated for 1 day (until the next feed). The acclimation period permitted oxygen level decrease to prevent inhibition of anaerobic bacteria as well as the bacteria population to adjust with the feed wastewater. The TSS concentration of the sludge after the 10-day batch-fed period was 16.5 g/l. A COD removal of about 59% was achieved at the end of this acclimation period.
During the experiment, COD reduction, pH and biogas production were monitored daily. The TSS reduction was usually measured every other day. Also oil reduction was checked 2 times throughout the experiment. The first check was after the end of the start-up period and the second check was after the completion of the whole experiment.
Results and discussion
COD removal efficiency
Biogas production rate
The overall performance of the reactor during the startup was satisfactory. It is known that the selection of seed material plays a crucial role in minimizing the time required for start-up duration . In addition, it is clearly understood that the initial immobilization of microorganisms on the surface of the support materials had a key role in progressing the start-up procedure.
Later operation stage
After a 49-days startup period, the reactor was operated at HRTs of 10 h and 8 h with three different influent COD concentrations (from 100 mg/l to 200 mg/l) to evaluate the effect of low organic loadings on the reactor performance.
COD and TSS removal efficiencies
Biogas production rate
The TSS concentration of the sludge in the reactor increased from 16.5 g/l at the beginning of the start-up to 67 g/l at the end of the study. This sludge production in the reactor may be attributed to (1) flocculation and entrapment of the non-biodegradable influent TSS, forming the inert sludge mass fraction and (2) the biological sludge mass that is generated as a result of anaerobic conversion in the hybrid reactor but because of the mentioned reasons in COD and TSS removal section, the entrapment of the suspended solids in the sludge seems to have more effect on increasing the TSS content of the reactor sludge. So, the sludge acted as a filter for removing the suspended solids from the wastewater . Therefore, the UASB reactor had a noticeable effect on removing the TSS content of the wastewater [34-36]. At the end of this study, a flocculent sludge was observed without any granule formation in it. As the other authors reported, low strength wastewater can lead to substrate transfer limitation and cause inhibition of granulation or can make it difficult to maintain granules [37,38].
In this study, anaerobic treatment of dilute bilge water was performed by using UASFF reactor at ambient temperature. After a good resulted immobilization of sludge in the support materials and start-up period, the COD and TSS removal efficiencies reached the amounts of 75% and 99% at the end of the operation, respectively. The results showed that the sludge blanket acted as a filter for removing the suspended solids from the wastewater and the major proportion of COD removal was due to the soluble and not suspended COD. The biogas production rate reached an amount of 0.93 l/day at the end of the experiment and effluent oil concentration is remarkably below the standard amount which has been set by the IMO (15 ppm). The good performance of the bioreactor on appearance of the wastewater can be considered as another advantage of this type of the UASFF reactor. The immobilization of the biomass in the support materials had an important role in reducing the influent COD because they created a good media for methanogenic bacteria on their surface. According to the obtained results, it can be concluded that the UASFF reactor is a very promising option for the treatment of the low-strength bilge water, produced from the ships in Caspian Sea, at the ambient temperatures for implementation on the ships in a large scale.
The authors wish to acknowledge Biofuel & Renewable Energy Research Center, Noshirvani University of Technology (Babol, Iran) for the facilities provided to accomplish the present research.
- MARPOL:International Convention for the Prevention of Pollution from Ships, 1973, as modified by the protocol of 1978 relating thereto (MARPOL 73/78). in: (IMO) I.M.O., ed; 1973
- Ghidossi R, Veyret D, Scotto JL, Jalabert T, Moulin P. Ferry oily wastewater treatment. Sep Purif Technol. 2009;64:296–303.View ArticleGoogle Scholar
- Peng H, Tremblay AY, Veinot DE. The use of backflushed coalescing microfilteration as pretreatment for the ultrafilteration of bilge water. Desalination. 2005;181:109–20.View ArticleGoogle Scholar
- Korbahti BK, Artut K. Electrochemical oil/water demulisification and purification of bilge water using Pt/Ir electrodes. Desalination. 2010;258:219–28.View ArticleGoogle Scholar
- Rincon GJ, La Motta EJ. Simultaneous removal of oil and grease, and heavy metals from artificial bilge water using electrocoagulation/flotation. J Environ Manage. 2014;144:42–50.View ArticleGoogle Scholar
- Karakulski K, Morawski WA, Grzechulska J. Purification of bilge water by hybrid ultrafiltration and photocatalytic processes. Sep Purif Technol. 1998;14:163–73.View ArticleGoogle Scholar
- Benito JM, Sanchez MJ, Pena P, Rodriguez MA. Development of a new high porosity ceramic membrane for the treatment of bilge water. Desalination. 2007;214:91–101.View ArticleGoogle Scholar
- Weiland P. Biogas production: current state and perspectives. Appl Microbiol Biotechnol. 2010;85:849–60.View ArticleGoogle Scholar
- Kivaisi AK. The potential for constructed wetlands for wastewater treatment and reuse in developing countries: a review. Ecol Eng. 2001;16:545–60.View ArticleGoogle Scholar
- Tchobanoglous G, Burton FL, Stensel HD. Wastewater Engineering: Treatment and Reuse. New York: McGraw-Hill Education; 2003.Google Scholar
- Liu Y, Tay JH. State of the art of biogranulation technology for wastewater treatment. Biotechnol Adv. 2004;22:533–63.View ArticleGoogle Scholar
- Goodwin JAS, Finlayson JM, Low EW. A further study of the anaerobic biotreatment of malt whisky distillery pot ale using an UASB system. Bioresour Technol. 2001;78:155–60.View ArticleGoogle Scholar
- Sabry T. Application of the UASB inoculated with flocculent and granular sludge in treating sewage at different hydraulic shock loads. Bioresour Technol. 2008;99:4073–7.View ArticleGoogle Scholar
- Kumar A, Yadav AK, Sreekrishnan TR, Satya S, Kaushik CP. Treatment of low strength industrial cluster wastewater by anaerobic hybrid reactor. Bioresour Technol. 2008;99:3123–9.View ArticleGoogle Scholar
- Chan YJ, Chong MF, Law CL, Hassell DG. A review on anaerobic–aerobic treatment of industrial and municipal wastewater. Cheml Eng J. 2009;155:1–18.View ArticleGoogle Scholar
- Aiyuk S, Amoako J, Raskin L, van Haandel A, Verstraete W. Removal of carbon and nutrients from domestic wastewater using a low investment, integrated treatment concept. Water Res. 2004;38:3031–42.View ArticleGoogle Scholar
- Gomec CY. High-rate anaerobic treatment of domestic wastewater at ambient operating temperatures: A review on benefits and drawbacks. J Environ Sci Health A Tox Hazard Subst Environ Eng. 2010;45:1169–84.View ArticleGoogle Scholar
- Leitao RC, Santaellla ST, van Haandel AC, Zeeman G, Lettinga G. The effect of operational conditions on the hydrodynamic characteristics of the sludge bed in UASB reactors. Water Sci Technol. 2011;64:1935–41.View ArticleGoogle Scholar
- DR/890:colorimeter, Procedures Manual, Method 8000. in: Hach Company L., CO, ed; 2009
- APHA. Standard methods for the examination of Water and Wastewater. Washington, DC: American Public Health Association/American Water Work Association/Water Environmental Federation; 2008.Google Scholar
- Zaiat M, Cabral AKA, Foresti E. Horizontal-flow anaerobic immobilized sludge reactor for wastewater treatment: conception and performance evaluation. Revista Brasileira de Engenharia. 1994;11:33–42.Google Scholar
- Sunil Kumar G, Gupta SK, Singh G. Biodegradation of distillery spent wash in anaerobic hybrid reactor. Water Res. 2007;41:721–30.View ArticleGoogle Scholar
- Zhang Y, Yan L, Chi L, Long X, Mei Z, Zhang Z. Startup and operation of anaerobic EGSB reactor treating palm oil mill effluent. J Environ Sci. 2008;20:658–63.View ArticleGoogle Scholar
- Van Haandel AC, Lettinga G. Anaerobic sewage treatment- a practical guide for regions with a hot climate. England: John Wiley & Sons; 1994.Google Scholar
- Najafpour GD, Zinatizadeh AAL, Mohamed AR, Hasnain Isa M, Nasrollahzadeh H. High-rate anaerobic digestion of palm oil mill effluent in an upflow anaerobic sludge-fixed film bioreactor. Process Biochem. 2006;41:370–9.View ArticleGoogle Scholar
- Selvamurugan M, Doraisamy P, Maheswari M. An integrated treatment system for coffee processing wastewater using anaerobic and aerobic process. Ecol Eng. 2010;36:1686–90.View ArticleGoogle Scholar
- Buyukkamaci N, Filibeli A. Volatile fatty acid formation in an anaerobic hybrid reactor. Process Biochem. 2004;39:1491–4.View ArticleGoogle Scholar
- Chan YJ, Chong MF, Law CL. An integrated anaerobic–aerobic bioreactor (IAAB) for the treatment of palm oil mill effluent (POME): Start-up and steady state performance. Process Biochem. 2012;47:485–95.View ArticleGoogle Scholar
- Sun C, Leiknes T, Weitzenbock J, Thorstensen B. Development of an integrated shipboard wastewater treatment system using biofilm-MBR. Sep Purif Technol. 2010;75:22–31.View ArticleGoogle Scholar
- Tawfik A, Sobhey M, Badawy M. Treatment of a combined dairy and domestic wastewater in an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system). Desalination. 2008;227:167–77.View ArticleGoogle Scholar
- Ligero P, de Vega A, Soto M. Influence of HRT (hydraulic retention time) and SRT (solid retention time) on the hydrolytic pre-treatment of urban wastewater. Water Sci Technol. 2001;44:7–14.Google Scholar
- Lettinga G. Anaerobic digestion and wastewater treatment systems. Antonie Van Leeuwenhoek. 1995;67:3–28.View ArticleGoogle Scholar
- Nadais H, Capela I, Arroja L, Duarte A. Optimum cycle time for intermittent UASB reactors treating dairy wastewater. Water Res. 2005;39:1511–8.View ArticleGoogle Scholar
- Álvarez JA, Ruíz I, Soto M. Anaerobic digesters as a pretreatment for constructed wetlands. Ecol Eng. 2008;33:54–67.View ArticleGoogle Scholar
- Green M, Shaul N, Beliavski M, Sabbah I, Ghattas B, Tarre S. Minimizing land requirement and evaporation in small wastewater treatment systems. Ecol Eng. 2006;26:266–71.View ArticleGoogle Scholar
- Ruiz I, Díaz MA, Crujeiras B, García J, Soto M. Solids hydrolysis and accumulation in a hybrid anaerobic digester-constructed wetlands system. Ecol Eng. 2010;36:1007–16.View ArticleGoogle Scholar
- Aiyuk S, Verstraete W. Sedimentological evolution in an UASB treating SYNTHES, a new representative synthetic sewage, at low loading rates. Bioresour Technol. 2004;93:269–78.View ArticleGoogle Scholar
- Aiyuk S, Xu H, van Haandel A, Verstraete W, Verstraete W. Removal of ammonium nitrogen from pretreated domestic sewage using a natural ion exchanger. Environ Technol. 2004;25:1321–30.View ArticleGoogle Scholar
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.