Start-up of Modified Anaerobic Baffled Reactor for the Treatment of Landfill Leachate by Using Granular Sludge

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 988-992

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

Start-up of Modified Anaerobic Baffled Reactor for

the Treatment of Landfill Leachate by Using

Granular Sludge

Imran Ahmad , Shreeshivadasan Chelliapan , Norazli Othman , Norhayati Abdullah and

Nithiya Arumugam²

Malaysia Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia

Department of Engineering, Razak Faculty of Technology and Informatics, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100, Kuala

Lumpur, Malaysia

Received: 23/01/2020

Accepted: 17/06/2020

Published: 20/09/2020

Abstract

The objective of this study was to valuate the start-up performance of the Modified Anaerobic Baffled Reactor (MABR) system by using

granular sludge treating landfill leachate. Anaerobic reactor start-up is a complex process as it depends on the substrate characteristics,

working conditions, inoculum and reactor configuration. To reduce the start-up time and have better operational parameters control in

anaerobic processes, important factors are needed to enhance the high-rate anaerobic systems efficiency. Sludge granulation was indeed an

achievement in anaerobic wastewater treatment technology and has greatly enhanced its efficiency and applicability. It holds many

advantages, such as mutual defence against antagonists, efficient reactor operation without sludge washout, and effluent with low suspended

solids. Granules are the functional units which comprise different microorganisms that are required for the methanogenic degradation of

organic matter. Results from this study showed a successful start-up of the MABR system at an organic loading rate (OLR) of 0.0875

kgCOD/m /d and hydraulic retention time (HRT) of four days. During this period the Chemical Oxygen Demand (COD) removal efficiency

was 99 % and the gas production increased steadily from 0.013 L/d to 0.021 L/d.

Keyword: Landfill leachate, Modified anaerobic baffled reactor (MABR), Granular sludge, Meat extract

Baffled Reactor (MABR) in this study was 35°C –40°C. Shorter

Introduction¹

start-up times can be made by using wastewater that is low in

particulate organics. When the organic loading rate (OLR) and

Chemical Oxygen Demand (COD) concentrations are reduced by

Out of the problems which are generally encountered in the

anaerobic treatment of wastewater, one of the problems is related

to the complication in start-up. This was discussed in previous

studies that a considerable amount of time was required in the

start-up of anaerobic systems [1]. The main issue of concern is the

development of microbial culture which is suitable the most to the

incoming wastewater, vulnerable nature of most anaerobic

bacteria and utmost oxygen liability of the enzyme systems of

obligate anaerobes renders the reactor population more

susceptible to slight fluctuations [1].

0% ,then the value of OLR should be increased[5]. If the time of

start-up of anaerobic reactors is reduced and the operational

parameters of the system are optimum, then it will contribute to

the increase in the efficiency of the anaerobic system [6]. The

objective of this study is to identify and evaluate the start-up

performance of the MABR by using synthetic wastewater (meat

extract).

Sludge granulation is indeed an achievement in anaerobic

wastewater treatment technology as granular sludge has many

advantages as compared to sewage sludge. Biomass retention is

possible inside the reactor without the supply of a carrier material,

thereby improving the economics of the process. Anaerobic

granules are basically the particulate biofilms, formed

impulsively by auto immobilisation of anaerobic bacteria in the

absence of a support media. These dense particles, consisting of

an entwined mixture of the collegial anaerobic micro-organisms

that work together in methane fermentation, are the driving force

While initialising the start-up of anaerobic reactor, the

biomass in the reactor system is to get acclimatised with the type

and strength of wastewater(substrate),operating parameters in the

reactor system and the configuration of the reactor.Additionally,

fast growing acidogens outnumber methanogens and certain

acetogen [2,4]. As a result, volatile acids (VA) and dissolved H

are accumulated. Generally, anaerobic reactors are commenced

on mesophilic temperature (33°C –40°C) and it advances the

growth of methanogens. The temperature maintained during the

treatment of landfill leachate by using Modified Anaerobic

Corresponding author: Imran Ahmad, Malaysia Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Jalan

Sultan Yahya Petra, 54100, Kuala Lumpur, Malaysia. Email: mustafwibinqamar@gmail.com.

988

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 988-992

for the successful operation of the modern, high-rate anaerobic

digester [7].

reactor is 82, 17 and 32 cm, respectively. The MABR is an

enhancement of the conventional ABR, whereby each

compartment is further supplemented by slanted baffles to

encourage mixing within the compartment and control sludge

washout. The MABR was designed and developed by [9]. A

synthetic wastewater (glucose) is used to start-up and evaluate its

reactor performances.

The granules are the functional units which comprise different

microorganisms required for the methanogenic degradation of

organic matter. A granule may contain millions of organisms in a

single gram of biomass. The unique spatial arrangement of

bacteria within an anaerobic granule and the phenomenon of

granulation offers many advantages: 1. Mutual defence against

antagonists; 2. Efficient reactor operation without sludge

washout; 3. Effluent with low suspended solids.Granular sludge-

based bioreactor technologies are recognised worldwide as cost-

effective and efficient for the anaerobic treatment of industrial

and municipal wastewater [8].

In this study, meat extract was used to investigate the

performance of the MABR during the start-up, which was

achieved by low OLR of 0.0875 kg COD/m /d and hydraulic

retention time (HRT) of 4 days, so that the substrate will

acclimatise with the anaerobic granular sludge, resulting in

efficient start-up of the MABR system. Gas production was

monitored on individual basis for each compartment by using

Tedlar bags of 1-litre capacity and bubble counters. It is cardinal

for an effective operation to control temperature since microbe

activity drops off extensively as temperature falls [10]. A timer

was applied for 15 min per hour to keep the uniformity of

temperature and avoid overheating of the compartments.

Peristaltic pumps were used to check and regulate the flow rate

for the influent.

Materials and Methods

.1 Modified Anaerobic Baffled Reactor (MABR)

Wastewater treatment emphasises on achieving these

requirements: a) Uncomplicated design, b) minimal construction

and maintenance cost, and c) high efficiency in treatment.

Anaerobic technology is favoured over aerobic technology

because anaerobic processes consume less energy and produce

less sludge, which directs to lower operational costs as compared

to aerobic processes.

ABR, which is a high-rate anaerobic reactor can be regarded

as one of the most efficient anaerobic treatment systems. ABR

can treat industrial wastewater, such as textile, pharmaceutical,

petrochemical, paper mill and others, respectively, which usually

contains recalcitrant (non-biodegradable) compounds. The

MABR is a laboratory scale plexiglass reactor which has 28 L

capacity and contains four uniform compartments (7 L capacities)

and each has a slanted baffle (45°), heater (to maintain the

temperature within mesophilic range) and sludge and gas

sampling ports (Figure 1). The length, width and height of the

2.2 Nutrients

Macronutrients N100 were used to overcome nutrient

deficiencies. Alkalinity of the feed was adjusted to 1000 mg/l –

2000 mg/l by adding NaHCO to the feed whenever it was needed.

2.3 Synthetic Wastewater

The synthetic wastewater consists of protein and other added

chemicals which is readily degradable. It produces actively

considerable intermediary metabolites in the anaerobic

degradation and was used as a carbonaceous substrate in past

research. Table 2 shows the characteristics of meat extract used

as synthetic wastewater.

Figure 1: Schematic diagram showing modified anaerobic baffled reactor (MABR)

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 988-992

Table 1: Characteristics of the N100

Table 3: Properties of granular sludge

Aggregation Thick fluid (sediment solids)

Nutrients

Composition

Nutrients

Composition

Crude fat

Odour

Colour

Light aroma of rotten eggs

Grey-black

Riboflavin

8.00 mg

(

min)

Crude fibre

max)

Selenium

Manganese

Zinc

0.00002%

0.09%

(

Solubility

Density

Pellet-like particles

Crude

protein

.0 to 1.1

(kg/l)

(min)

Acidity (pH) 7 to 9

Nitrogen

free extract

0.005%

Stable at ambient temperatures and under

normal conditions of usage.

Reactivity

Boron

0.018%

Folic Acid

Vitamin A

Niacin

0.30 mg

Chemical

Stability

The product is quite stable

Calcium

Cobalt

50,000 IU

25.00 mg

0.0008%

Pantothenic

Acid

3 Results and Discussions

3.1 pH

Copper

0.0005%

0.20 mg

The groups of microorganisms which are viable for the

anaerobic degradation have a defined range for their most

favourable growth, and values outside this range can cause

adverse impact to the process, especially methanogens.Therefore,

stable pH value within the digester should be one of the priorities

in ensuring efficient methanogenic digestion. The start-up of the

MABR lasted for 28 days. During the start-up, a determined

concentration of feed COD (350 mg/L) was kept until a steady

state COD removal and pH value were achieved, respectively.

Fluorine

Iodine

0.015%

0.03%

0.08%

0.50%

Thiamine

Choline

Biotin

3.00 mg

50.00 mg

0.30 mg

150 IU

Iron

Magnesium

Vitamin E

Vitamin

B12

Ascorbic

Acid

Potassium

0.04 mg

Salt

1500.00 mg

1.00 mg

The OLR and HRT were also maintained at 0.0875 kgCOD/m /d

Sulphur

Vitamin K

and four days, respectively. Figure 2a illustrates the pH profile

during start-up period. The pH levels during reactor start-up by

using the synthetic wastewater were generally stable (pH 7.0 – pH

8.1) in all compartments of the MABR until Day 12, whereby a

slight reduction (pH 6.3 – pH 6.7) was observed in all

compartments from Day 16–Day 20, of the MABR, but it

recovered to stable conditions on Day 28. For anaerobic digestion,

the alkaline phase is preferred to maintain stable microbial

populations in the sludge. Many anaerobic reactors fail to operate

at low pH (less than 6.7). It is important to maintain a suitable

alkalinity in the reactor. Also, in literature many anaerobic

reactors were operated in the alkaline region [12]. The variations

in pH were caused by biochemical processes (acidogenesis and

methanogenesis) which were taking place in the same reactor.

Conversion of reactant to substrate by the anaerobic bacteria,

which was not stable during the anaerobic digestion, caused the

fluctuation of pH. However, the behaviour from 20–28 days,

showed that the pH values were stabilising.

Table 2: Ingredients of meat extract used as synthetic

wastewater

Ingredients of meat extract

Energy

Weight per 100 g

983 kJ

Calories

Protein

231 kcal

38.4 g

Carbohydrates

Fat

19.2 g

0.1 g

Fibre

3.1 g

Sodium

4.3 g

salt

11 g

Thiamin

Riboflavin

Niacin

Folic acid

Vitamin B12

5.8 mg

7.0 mg

160.0 mg

2500 μg

15.0 μg

.2 COD

The COD removal efficiency during start-up showed a steady

.4 Granular Sludge

Seed sludge which was used in MABR system for the start-

up was obtained from an anaerobic digester treating food

waste.The sludge is a naturally occurring biocatalyst having its

wide application as inoculation material for the start-up of

bioreactors for the anaerobic treatment of wastewater. Table 3

shows the properties of the granular sludge.

increase from Day 1 up to Day 28 (Figure 2b). The MABR was

started at an OLR of 0.0875 kgCOD/m /d and long retention time

(

four days), Solids will be accumulated in the reactor with

increased methanogenic populations and resilience to hydraulic

shock load ``[13]. The COD removal efficiency, increased at a

steady rate from 58% to 99%, affirming that the reactor start-up

was efficient. Regardless of low pH levels were noticed during

the initial operational period (until Day 12), the removal rate of

COD was still high, showing that the performance was not

affected by the fluctuation of pH.

.5 Sampling and analysis

Sample analysis, such as COD and pH were conducted

according to standard methods [11] by using DR 6000

spectrophotometer. The total biogas volume was determined by

using an optical gas bubble counter.

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 988-992

(a)

(b)

(c)

(d)

Figure 2: (a) pH profile during start-up of MABR (b) COD removal during start-up of MABR (c) VA profile during start-up of MABR (d) Biogas

production during start-up MABR

.3 VA

VA is a useful indicator to evaluate the anaerobic reactor

monoxide, acetic and formic acids. Secondly, these become the

food for the other group which further change it into desired

methane and carbon dioxide [16, 17]. The environmental

advantage of biogas is that it is sustainable alternative to fossil

fuels. It reduces Green House Gases (GHG) emissions; hence, it

is an ecofriendly gas. Figure 2d shows the total gas production

during reactor start-up. It can be seen that the gas output increased

steadily from 0.013 L/d to 0.021 L/d during the functional period,

confirming that the degradation of the substrate was taking office.

performance. The more VA is being utilised inside the reactor, the

better the reactor operation. According to [14] VA of less than

50 mg/L in an anaerobic reactor, indicated that the reactor was

operating under stable conditions. In general, if the pH of the

reactor system is high (e.g. pH 7 – pH 7.5), the VA should be

lower [15], and in the current study, this trend was clearly

observed (Figure 2c). The VA concentration in all compartments

during reactor start-up by using the synthetic wastewater was

stable throughout the study (40 mg/L – 95 mg/L HOAC),

confirming a stable operation of the reactor. In the current study,

acetic acid was evaluated for the acid concentration in the reactor

due to its main desire for methanogenic digestion. Low VA

concentration was observed in C4 (around 40 mg/L HOAC)

throughout the start-up.

Conclusion

The performance of MABR during rector start-up by using

granular sludge showed successful treatment of a promising

method for wastewater treatment (performance treating synthetic

wastewater). The MABR showed a successful start-up at an OLR

and HRT of 0.0875 kgCOD/m /d and four days, respectively, by

using the synthetic wastewater (meat extract). A COD removal

efficiency of 98.5% was observed during this period.

.4 Biogas

The anaerobic microorganisms cause breakdown of the

organic waste in a digester in the absence of oxygen to give

biogas. The degradation of organic matter is a consequence of the

operation of two important groups of microorganisms. Firstly, the

acid forming bacteria which break down complex organic

compounds (proteins, fats and carbohydrates) into simpler ones

like volatile fatty acids, lower alcohols, hydrogen, carbon

Acknowledgement

The authors wish to thank Universiti Teknologi Malaysia for

funding this study under the GUP Tier 1 Vote Number

Q.K130000.3040.01M17 and the conference fee from the

Fundamental Research Grant Scheme (FRGS) Vote Number

R.K130000.7856.5F049.

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Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 3, Pages: 988-992

Barber, W. P. and Stuckey, D. C. The use of anaerobic baffled reactor

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(ABR) for the wastewater treatment: A review. Water Res. 1999,

Authors are aware of, and comply with, best practice in

publication ethics specifically with regard to authorship

3(7), 1559-1578.

Damasceno L.H.S., Rodrigues J.A.D., Ratusznei S. M., Zaiat M. and

Foresti, E. Effects of feeding time and organic loading in an

anaerobic sequencing batch biofilm reactor (ASBBR) treating diluted

whey. J. Environ. Manage. 2007, 85, 927-935.

(avoidance of guest authorship), dual submission, manipulation

of figures, competing interests and compliance with policies on

research ethics. Authors adhere to publication requirements that

the submitted work is original and has not been published

elsewhere in any language.

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and distributions of c, n, and p in the anaerobic digestion of different

substrates and relationships between products and substrates. Chem.

Eng. 2016, 287, 329–336.

Competing interests

The authors declare that there is no conflict of interest that

would prejudice the impartiality of this scientific work.

Makisha Nikolay and Semenova Daria. Production of biogas at

wastewater treatment plants and its further application MATEC Web

of Conferences. 2018, 144, 04016,1-7. International Conference on

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Goli A, Shamiri A, Khosroyar S, Talaiekhozani A, Sanaye R, Azizi

K. A Review on different aerobic and anaerobic treatment methods

in dairy industry wastewater. J Environmental Treatmnt Techniques,

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All authors of this study have a complete contribution for data

collection, data analysis and manuscript writing.

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