Elsevier

Process Biochemistry

Volume 38, Issue 5, 31 December 2002, Pages 771-775
Process Biochemistry

Concentrated wastewater treatment studies using an anaerobic hybrid reactor

https://doi.org/10.1016/S0032-9592(02)00221-2Get rights and content

Abstract

The treatment performance of an anaerobic hybrid reactor was investigated for different types of concentrated wastewater using a laboratory scale model reactor. Its performance was first examined using synthetic wastewater at different hydraulic retention times (0.5, 1 and 2 days) and organic loading rates (1–10 kg chemical oxygen demand (COD) m−3 per day) over 2 years. COD removal efficiencies ranging from 77 to 90% were achieved. Baker's yeast and meat processing industry wastewater was fed to the model reactor, consecutively. HRT and OLR values were 2 days—9.0 kg COD m−3 per day and 2 days—1.0 kg COD m−3 per day, and about 78 and 75% COD removal efficiency was obtained for yeast and meat industry wastewater, respectively. The methane content of the biogas produced was about 58, 58, and 70% for synthetic, yeast industry and meat processing wastewater, respectively. The organic matter removal efficiency of the reactor indicated that this type of reactor is suitable for treatment of high strength effluent.

Introduction

Anaerobic filters were first described in 1968 and have been used as an advanced technology for effective treatment of a variety of industrial wastes. Fixed bed anaerobic treatment processes are applicable to wastewaters with low (<1000 mg chemical oxygen demand (COD) l−1) to intermediate (>20 000 mg COD l−1) concentrations. Originally upflow anaerobic filters were 100% packed, but some researchers pointed out that if the amount of support material is decreased, some disadvantages of fully packed anaerobic filters can be overcome [1], [2]. This kind of reactor is called as ‘hybrid’ reactor and it combines a upflow anaerobic sludge blanket/bed (UASB) in the lower part with a filter in the upper part. The hybrid reactor promotes the advantages of the UASB and AF reactors, while minimising their limitations. The performance of hybrid upflow anaerobic filters depends on contact of the wastewater with both the suspended growth in the sludge layer and the attached biofilm in the media matrix.

A fully packed upflow anaerobic filter was compared with a hybrid with 50% or less packing. In the partially packed reactor, increased solids loss was generally experienced as well as reduced efficiency. Some investigator found that the fully packed upflow anaerobic filter gave the highest degree of solids retention and the lowest yield. Some investigator also found that a fully packed upflow filter performed significantly better than a hybrid with only the top 2/3 packed [3].

In this study, treatment of different types of concentrated wastewater was investigated using a laboratory scale anaerobic hybrid model reactor. At the beginning of the study, the model reactor was operated using synthetic wastewater containing molasses, before running with real industrial wastewater. Treatment efficiencies in the model reactor were investigated at different hydraulic retention times (0.5, 1 and 2 days) and organic loading rates (1–10 kg COD m−3 per day) with synthetic wastewater. Then depending on the results obtained in studies carried out with synthetic wastewater, the model reactor was operated using effluent from the Baker's yeast and meat processing industries.

The aim of this work was to investigate the performance of an anaerobic hybrid reactor using different concentrated wastewater with different operational conditions. System performance was evaluated by COD removal efficiency and methane production.

Section snippets

Model reactor

In this study, a standard type laboratory scale hybrid reactor was used. A schematic diagram of the model reactor is given in Fig. 1. This reactor was made of Plexiglas material (25 cm in diameter×115 cm total height×102 cm liquid height) and upper two-third of the reactor was operated as a fixed bed reactor. The support material used in the fixed bed was hose pieces with 3 cm long (specific surface area 225 m2 m−3). The total volume of the reactor was 53.6 l and the volume of liquid was 50 l.

Performance of the reactor

Fig. 2 shows the performance of the hybrid model reactor for synthetic wastewater treatment studies for a period of over 2 years from the start-up (Phase I). Changing the hydraulic retention time and influent COD concentrations, 11 different operational conditions were applied and COD removal efficiencies ranging from 77 to 90% were achieved. The percentage of methane gas of the total biogas was about 58% and the average methane gas yield was 0.32 m3. CH4 gas produced per kg removed COD per day

Conclusions

After obtaining steady-state conditions, organic loading rate was increased from 1 to 10 kg COD m−3 per day and hydraulic retention times were decreased from 2 to 0.5 days, stepwise. About 11 different operational conditions were applied changing these two parameters in a certain program. COD removal efficiencies ranging from 77 to 90% were achieved during the experimental studies. The percentage of methane gas of the total biogas was about 58%. The amount of methane gas produced per kg of COD

Acknowledgements

The authors gratefully acknowledge the Scientific and Technical Research Council of Turkey (TUBITAK), Research Foundation of Dokuz Eylul University, PAKMAYA Baker's Yeast Factory, and TANET Meat Processing Industry.

References (8)

There are more references available in the full text version of this article.

Cited by (23)

  • Different treatment methodologies and reactors employed for dairy effluent treatment - A review

    2022, Journal of Water Process Engineering
    Citation Excerpt :

    Anaerobic baffled reactor (ABR) is one of the most uncomplicated and affordable reactors suitable for developing countries with minimal operating and maintenance costs. Sludge washout and low biogas production are the disadvantages of ABR, even though the sludge washout problem can be eliminated by incorporating granular or flocculent biomass combination with fixed films in the reactor design [76]. Such reactors are hybrid baffled biofilm reactors (ABBRs), the clone version of UASB with a filter positioned at the lower and upper portions of the reactor design.

  • Long term performance of a pilot scale anaerobic membrane bioreactor treating beet molasses based industrial wastewater

    2021, Journal of Environmental Management
    Citation Excerpt :

    Several other methods including ozonation, electrocoagulation and membrane processes have also been investigated for treatment of BYI effluents (Balcıoğlu and Gönder, 2018; Al-Shannag et al., 2014; Gengec and Kobya, 2013). Various lab-scale anaerobic reactor configurations such as upflow anaerobic sludge blanket (UASB) reactor (Mischopoulou et al., 2017; Kalyuzhnyi et al., 2005a, 2005b; Gladchenko et al., 2004; Gulmez et al., 1998), anaerobic baffled reactor (Pirsaheb et al., 2015, 2018), anaerobic filter (Van der Merwe and Britz, 1993), hybrid filter (Büyükkamaci and Filibeli, 2002) and anaerobic rotating biological contactor (Lo and Liao, 1990), were investigated for the treatment of BYI effluents and moderate (50%) to high (90%) COD removal efficiencies were obtained. Results from full-scale UASB reactors treating BYI wastewaters also confirm that 50–75% COD removal efficiency is attainable in practice (Ciftci and Ozturk, 1993; Zub et al., 2008).

  • A review on anaerobic biofilm reactors for the treatment of dairy industry wastewater

    2015, Process Biochemistry
    Citation Excerpt :

    Polymer formation occurred when OLR was over 4.5 kg COD m−3 d−1 while other researchers reported lower OLR values for ASBBR instability during the dairy wastewater treatment [90]. In order to improve treatment the performance and overcome the deficiencies, hybrid anaerobic biofilm reactors have been developed by combining the properties of biofilm reactor and another reactor systems [91,92]. In recent years, hybrid anaerobic biofilm reactors have been widely applied for the treatment of dairy wastewater and performance comparison along with operating conditions are given in Table 5.

View all citing articles on Scopus
View full text