Effectiveness of Advanced Vs Conventional Wet Coffee Processing Technologies in Effluent Wastewater Quality

International Journal of Scientific & Engineering Research, Volume 4, Issue 8, August-2013 1236

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Effectiveness of Advanced Vs Conventional Wet Coffee Processing Technologies in

Effluent Wastewater Quality

Tsigereda Kebede Tilahun, Metadel Adane Mesfine, Mekibib David Dawit, Fisseha Ittana

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Corresponding Author: Metadel Adane M. Wollo University, Dessie, Po.Box 1145. Email: Shirley.meta6@gm ail.com.

Abstract

This study examined the effluent suitability for discharge of newly emerged advanced wet coffee processing technologies compared to the conventional systems. A descriptive study design was employed and composite samples were analyzed in triplicate for selected physicochemical parameters (COD, BOD5, DO, NH3, PO43-, NO3 --N, pH, TSS, TDS, conductivity, and turbidity). Consequently, the mean results obtained from conventional wet coffee processing technologies were BOD5 (1697 mg/L), COD (5682.5 mg/L), TSS (1975 mg/L), TDS (1800.75 mg/L), and pH (4.13). Whereas mean values of the selected physic-chemical parameters from wastewater of advanced wet coffee processing technologies were BOD5 (2687 mg/L), COD (3567 mg/L), pH (6.69), and TSS (282.42). Even though there was significant variation between conventional and advanced wet coffee processing effluent wastewater; both wet coffee processing technologies did not comply with Ethiopian permissible discharges limit standards for BOD5, COD and TSS. Hence, establishing advanced wet coffee technologies does not seem to solve the pollution problems associated with coffee processing. As a result, effluent wastewater treatment systems are needed for both technologies before discharging to prevent surface water pollution.

Index terms: Coffee processing technologies, Effluent, Wet Coffee, Wastewater

1 INTRODUCTION

Ethiopia is the largest country producing
diversity of coffee from its genetic resource (2). Coffee was originally found and cultivated in Kafa province of Ethiopia from which it got its name around 1000 A.D. (1). After harvesting, coffee can be processed in two ways; these are dry (natural) processing and wet (washing)
processing.
Wet processing is done with the help of water,
especially to remove the outer red skin and the white fleshy pulp (9). Wet coffee processing can be done in conventional system, as most of the processing plants do in Ethiopia. The advanced way is currently being practiced in near Jimma, Ethiopia. These technologies are expected to
increase the quality of the product and safeguard

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the environment from pollution. However, the
potential of these advanced wet coffee processing systems in achieving the required discharge standard limits has not been studied relative to the conventional technologies for proper wastewater management. Hence, this study deals with the characteristics of both technologies wastewater effluent in order to examine the effluent wastewater quality by comparing with the available standards. The study will help to evaluate the potential of the newly emerging advanced wet processing plants in meeting the effluent discharge standards compared to the usual conventional wet coffee processing technologies.

2 MATERIALS AND METHODS

2.1 Study area description

The study was conducted in Doyo, Seka, Geruke and Haro districts of Jimma Zone, around 12 km west, 20 km south west, 25 km to east direction and 15 km to south east of Jimma, respectively. In Doyo and Seka study areas advanced wet coffee processing is practiced while in Geruke and Haro study areas conventional wet coffee processing technologies are used. Jimma is located at 352 km from Addis Ababa in south- west Ethiopia. Jimma lies between 7o20 0 N and
8o55 0 N latitude and 35o45 0 E and 37o 35 0 E
longitude maximum annual temperature of
Jimma is 27.5oC whereas minimum annual
temperature is 10.47oC and annual rainfall is
495.6 mm.

2.2 Study design

A descriptive study was conducted from October, 2011 -June, 2012 in order to characterize the influent and effluent wastewater of conventional and advanced wet coffee processing technologies.

2.2.1 Sampling Techniques

Composite samples were collected using polyethylene bottels (1000 ml) from each sampling sites in triplicate from influent water and effleunt wastewater. Samples were analyzed for pH, TSS, TDS NH3 , NO3 --N -, PO4 3- DO, BOD5
COD, conductivity and turbidity.
2.2.2 Laboratory analysis: pH, DO, conductivity and turbidity were measured onsite using APHA procedures (3). BODs, COD TSS, TDS, NO3 -N, NH3 and PO4 3-, were also analyzed using HACH procedures (5).

2.2.3 Data analysis

Statistical analyses were performed using SPSS version 16 to measure mean and standard deviat ion of the laboratory results. The levels of selectd parameters from conventional and advanced wet coffee processing technologies were compared with Ethiopia EPA permissible
discharge limit standards to surface water (4).

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3. RESULTS AND DISCUSSION

This study revealed that both wet coffee processing technologies wastewater did not comply with the Ethiopian EPA discharge limit standards to surface water (4) for most of the parameters such as BOD5 , COD and TSS (Table
3.2 and 3.3). This can contribute to surface water pollution. Similar study by Matos (6) revealed that coffee wastewater has high pollutant potential of BOD5 , COD and TSS. The pH of advanced wet coffee processing technologies effluent (6.69) is better than the pH of convention al wet coffee processing (4.13). However, the adv anced wet coffee processing technologies effluent wastewater BOD5 (2687 mg/L) is higher than the conventional wet coffee wastewater technologies (1697 mg/L). The high BOD5 from advanced wet coffee processing technologies may be due to the high fermentation process (7). For some parameters, the raw water characteristics did not
comply with the Ethiopia EPA (4) discharge
standards and WHO (8) discharge standards
(Table 3.1). The raw water BOD5 , COD, TSS for conventional wet coffee technologies was 214.25 mg/L, 233.5 mg/L and 259.5 mg/L, respectively (Table 3.1). This showed that even the raw water is not safe for coffee processing and the source of the water should be treated before processing or the source should be from the clean water that meets the Ethiopian EPA (4) or WHO (8) guidelines for processing wet coffee.

Fig 3.1.Mean BOD5 comparison of conventional and advanced wet coffee processing plants effluent wastewater

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Table 3.1.Characteristics of raw water used in advanced and Conventional wet coffee processing plants

Advanced	Conventional
Parameter	Mean + SD	Range	Means ± SD	Range
pH	6.92 ± 0.637	6.87 - 7.01	7.01 ± 0.55	6.19 - 7.35
BOD5 mg/L	96.25 ± 17.36	81.8 - 120.2	214.25 ± 81.33	113 – 312
COD mg/L	130 ± 14.8	110 – 146	233.5 ± 79.4	155 – 324
NH3 mg/L	0.94 ± 0.42	0.34 - 1.24	0.78 ± 0.28	0.37 - 0.96
NO3 -Nmg/L	1.41 ± 0.43	1 – 2	0.98 ± 0.22	0.66 - 1.13
PO4 3- mg/L	0.27 ± 0.11	0.18 - 0.42	0.34 ± 0.16	0.18 - 0.54
TSS mg/L	238.25 ± 53.1	198 – 312	259.5 ± 65.3	170 – 322
TDS mg/L	190.75 ± 20.9	178 -222	189.5 ± 46.5	143 – 254
EC (µs/cm)	70.25 ± 10.24	58 - 83	65.8 ± 4.24	61 – 71
NTU mg/L	22.6 3 ± 8.51	16 - 35	32.28 ± 9.64	23 – 45
DO mg/L	7.48 ± 1.07	6.2 - 8.7	6.34 ± 0.6	5.74-7.02

3.2. Physico-chemical characteristics of effluent wastewater from advanced coffee processing plants

Parameter	Mean ± SD	Range
pH	6.69 ± 0.12	6.54 - 6.82
BOD5 mg/L	2687 ± 518.04	2220-3356
COD mg/L	3567 ± 667.7	2580-3990
NH3 mg/L	11.85 ± 4.13	8.44 - 17.08
NO32- mg/L	2.04 ± 0.34	1.67 - 2.51
PO43- mg/L	2.26 ± 0.68	1.75 - 3.27
TSS mg/L	282.42± 44.75	216 – 312
TDS mg/L	789.25 ± 72.3	698 – 854

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EC (µs/cm)	350 ± 68.66	315 – 453
EC mg/L	91.25 ± 31.4	57 – 126
DO mg/L	4.38 ± 0.63	3.70 - 5.20

Table 3.3. Physico-chemical Characteristics of conventional wet coffee processing plants effluent
wastewater

Parameter	Mean ± SD	Range	Ethiopia EPA (2003) Standards
pH	4.13 ± 0.23	3.9 - 4.4	6-9
BOD5 mg/L	1697 ± 390.67	1210-2130	80
COD Mg/L	5682.5 ± 304.45	5470-6120	250
NH3 mg/L	4.51 ± 1.62	3.15- 6.65	5
NO3 -N mg/L	3.39 ± 0.65	2.70 - 4.12	20
PO43- mg/L	3.32 ± 0.5	2.71 - 3.45	5
TSS mg/L	1975 ± 322	1564 – 2310	100
TDS mg/L	1800.75 ± 244.8	1580 – 2133	3000
EC	747 ± 64	663 – 821	-
NTU mg/L	271 ± 128.5	185 – 458	-
DO mg/L	2.14 ± 0.72	1.09 - 2.7	-

Table 3.4. Physico-chemical characteristics of conventional wet coffee processing plants wastewater

Parameter	Mean ± SD	Range	Ethiopia EPA, 2003 Standards
pH	4.13 ± 0.23	3.9 - 4.4	6-9
BOD5 mg/L	1697 ± 390.67	1210-2130	80
COD mg/L	5682.5 ± 304.45	5470-6120	250
NH3 mg/L	4.51 ± 1.62	3.15- 6.65	5
NO3 -N mg/L	3.39 ± 0.65	2.70 - 4.12	20
PO43- mg/L	3.32 ± 0.5	2.71 - 3.45	5

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TSS mg/L	1975 ± 322	1564 – 2310	100
TDS mg/L	1800.75 ± 244.8	1580 – 2133	3000
EC (µs/cm)	747 ± 64	663 – 821	-
NTU mg/L	271 ± 128.5	185 – 458	-
DO mg/L	2.14 ± 0.72	1.09 - 2.7	-

Plate 3.1 Vetiver grass grow under wastewater from conventional wet coffee processing plants

nt
It was observed that plants grown under
wastewater effluent from advanced wet coffee processing plants were greenish (Plate 3.2). However; plants grown around wastewater of conventional wet coffee processing did not resist and grow properly (Plate 3.1). This was due to
wastewater released from conventional wet
coffee processing plants being acidic (Table 3.4),
whereas effluent pH from advanced wet coffee processing was close to neutral (Table 3.2).

4. Conclusion

Both advanced and conventional wet coffee processing technologies did not comply with the

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Ethiopian permissible discharge limit standards
for BOD5 , COD and TSS although some paramete rs met the required standards. This means that the advanced wet coffee processing technologies did not released sufficiently clean discharge to the environment. Therefore, there is a need to introduce wastewater treatment systems for both technologies to safeguard the environment. The raw water used for processing both technologies was not safe for coffee processing. Hence, safe water sources need to be identified and used for coffee washing.
The authors gratefully appreciated the special
support from Fiche Land and Environmental Protection, Ethiopian Coffee Initiative Update Techenoserve and Jimma University.
Environment and Coffee Forest Forum was also duly acknowledged for funding this project. References
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