Wet Coffee Processing Discharges Affecting Quality of River Water at Kayanza Ecological Zone, Burundi

Wet coffee processing leads to the generation of large volumes of wastewater, whose discharge to the environment leads to pollution of freshwater bodies. Kayanza is a major coffee growing area in Burundi with more than 40 wet coffee processing factories (WCPF) that discharge effluents directly to receiving water bodies without treatment. This study was carried out to assess the effect of coffee wastewater on the physicochemical properties of receiving waterbodies in Kayanza coffee growing ecological zone. Currently, no study has been done to analyze the effluent from the WCPF and assess the level of pollution. This study will therefore provide valuable data on the water pollution from coffee processing plants. Ten (10) rivers in the Kayanza coffee growing zone were studied during the months of April and June, 2020. Water samples were collected upstream (U) and downstream (D) of the effluent discharge points in triplicate. Samples were analyzed for pH, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD 5 ), Temperature, Salinity, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Total Suspended Solids (TSS), Nitrates, Nitrites, Lead (Pb), Copper (Cu), Chlorides and Ammonium ions using standard methods. Physical parameters were analyzed in situ whereas chemical parameters were analyzed in the laboratories in Burundi Institute of Agricultural Sciences (ISABU) and University of Burundi. Data were analyzed using R-studio-1.0.153, GenStat 64-bit Release 14.1 and SSPS. Results on the physicochemical parameters indicated that coffee factory effluent has a polluting potential during coffee processing peak. The concentrations of the physicochemical parameters were significantly (p < 0.05) higher downstream (D) compared to upstream (U) of the river water sampling points. All downstream sites had COD, BOD 5 , TSS and pH values above allowable limits set by WHO and Burundi. The polluting impact of public wet coffee processing factories was significantly higher than that of private and cooperatives owned factories (p < 0.05). Measures should be taken in order to protect water bodies.


Introduction
In developing countries, scarcity and water pollution constitute a primary challenge for sustainable water resources management. Coffee effluent's impact on water quality is of great concern. This is because it has been observed that the quality of water has a great effect on human health, exposing the environment to several hazards [1]. It becomes pertinent to carry out Environmental Impact Assessment (EIA) for any proposed wet coffee processing plants and Environmental Audits for existing factories. Inefficient use of water, contaminated water sources and use of polluted water in the wet processing of coffee cherries are all major issues in Burundi and other coffee producing countries [2] [3]. Currently, none of the wet coffee processing factories in Kayanza, has installed appropriate wastewater treatment technologies to improve the quality of the coffee wastewater to meet the set discharge standards.
By 2020, Kayanza had more than 40 wet coffee processing (WCP) plants (18 Publicly, 12 Privately and 9 Cooperatively owned functional wet coffee processing factories). Only Private and Cooperative owned factories had begun to operate the coffee wastewater treatment systems. The common wet coffee processing method used in Kayanza zone produces a significant amount of wastewater with a high pollution load because wet coffee processing factories are one of the significant consumers of water and produces a large amount of wastewater. This wastewater is later discharged into the river system polluting the water and negatively impacting the natural ecosystem and health of the local communities.
Coffee wastewater contains high concentrations of organic matter, suspended matter and is highly acidic [4]. Organic load is measured in terms of COD (Chemical Oxygen Demand) and BOD 5 (Biological Oxygen demand during five days), while acidity in terms of pH, and suspended matter in terms of total suspended solids (TSS). Considering the volume generated and the pollutants from the coffee wastewater, the wet coffee processing plant represents one of the main contributors to severe pollution problems. It was reported that all public wet coffee processing factories, even those with wastewater treatment plants do not treat the wastewater appropriately and discharge untreated, colored and acidic effluent into the nearby water bodies, streams and open land [4] [5]. This can have a serious negative impact on both the health of the surrounding population

Study Area
The study was conducted in Kayanza Province, one of the coffee growing eco- East. The area ranges from 1500 to 1850 meters above sea level with a temperature range of 15˚C to 17˚C. The area receives rainfall between 1200 to 1400 mm annually.

Water Sampling and Preservation
Samples were collected during peak seasons of April/Wet season and June/Dry season. Ten (10) rivers were selected in Kayanza coffee growing ecological zone according to Mugenda and Mugenda approach [8]. In order to assess the effect of the wastewater from the factories on the physicochemical properties of the receiving water bodies in Kayanza province, water samples were taken from rivers/streams that receive wastewater from the wet coffee processing factories at upstream and downstream of the discharge points (Table 1 & Figure 3).
The samples were collected using sampling procedures described in APHA, 1995 [9]. Onsite pretreatment was done for all parameters analyzed in the laboratory except water samples for the analysis for TSS, Chlorides and BOD 5 . All samples were collected using pre-cleaned plastic bottles. Open Journal of Applied Sciences

Experimental Design
Samples were analyzed in triplicates. Physical and chemical analyses were carried out in order to assess the effect of coffee processing wastewater being discharged without adequate treatment.

Analytical Procedures
Samples were analyzed onsite for pH, Temperature (T˚), salinity, Electrical Con- where X = Volume of titrant used for titration of sample; sample V = Volume of sample.

Data Processing and Analysis
The data were statistically analyzed using MS-Excel 2016, R-studio-

Results and Discussions
The comparison of the value of water quality parameters using box and whisker plot are presented ( Figure 4) and the overall assessment and classification of stagnant and running surface water according to their river water quality have been given in Table 2 to compare the pollution level of wastewater generated from the coffee processing plant and for the nearby waterbodies receiving this wastewater.
Higher concentration of the various physicochemical paremeters was obtained at downstream (D) sites than upstream (U) according to the values presented in    especially harmful to immature fish and insects. Acidic water also speeds the leaching of heavy metals harmful to fish [14]. This finding is in consistent with similar study done in Jimma zone by Dejen Yemane Tekle et al., 2015 [15], reported that high pH was observed at upstream sites than downstream sites. Unlike the other parameters, the amount of pH was found high in the upstream site (7.11) and reduced pH values at downstream locations of most rivers. The temperature at downstream of the rivers during the wet and dry seasons was found to be within the range of 20.8˚C -24.2˚C with a mean of 22.7˚C ± 1.38˚C and 20.5˚C -23.5˚C with a mean of 21.8˚C ± 1.24˚C respectively. This displayed wide variations among sampling locations and did not change significantly (p < 0.05) during seasons. The temperature in the upstream rivers ranged from 19.2˚C -23.9˚C with a mean of 22.5˚C ± 1.76˚C in wet season as compared to the results recorded in dry season which ranged from 19.2˚C -22.5˚C with a mean of 21.8˚C ± 1.54˚C varied from one river to another in Kayanza agro ecological Zones in Burundi and were below 25˚C, which is the set limit for no risk as per the WHO, FAO quality guidelines for discharging effluent to natural surface water bodies. These results are in agreement with preceding work undertaken by Hadis and Devi (2007) in Jimma zone in which the water temperature downstream of receiving waterbodies after receiving coffee effluents was reported as 22˚C. Based on the findings and on the guidelines, the temperature of the effluent did not pose any threat to the water ecosystem of the receiving water bodies [10] [11]. There was no significant difference in temperature values between the two seasons at 95% confidence interval.
The EC of the water reflects of quantity of dissolved ionic constituents. The EC profile of the upstream and downstream water bodies varied significantly (p < 0.05) and ranged from 41.9 -114.5 µS/cm with a mean of 77.5 ± 19.73 µS/cm and from 47.6 -184.1 µS/cm with a mean of 85.6 ± 18.62 µS/cm respectively up stream's results recorded in wet and dry seasons. While the down stream's results recorded in wet and dry seasons ranged respectively from 42.6 -277.7 µS/cm with a mean of 104.1 ± 34.25 µS/cm and from 54.6 to 360.3 µS/cm with a mean of 206.5 ± 102.13 µS/cm. These values were low all long the sampling points as compared to the provisional river water quality limit [10] [11]. The high EC downstream can be attributed to the high mucilage from wet coffee processing effluents. A sudden increase or decrease in conductivity in body of water can indicate pollution Agricultural runoff or sewage could increase EC due to the additional of chlorides, phosphates, Nitrates. In this case the additional of dissolved solids will have a negative impact on water quality.
The mean concentration of TDS was found to be in the range of 20.6 -57.4 mg/l with a mean of 37.0 ± 7.58 mg/l and 23.8 to 92.3 mg/l with a mean of 45.2 ± 13.02 mg/l respectively for up stream's results recorded in Wet and Dry seasons while the down stream's results recorded in Wet and Dry seasons varied respectively from 21.3 -137.7 mg/l with a mean of 67.8 ± 31.87 mg/l and from 27.7 to 186.9 mg/l with a mean of 124.1 ± 48.6 mg/l. The TDS of the water samples generally varied significantly (p < 0.05) through the study period. High TDS (67.8 -Open Journal of Applied Sciences 124.1 mg/l) were found at the downstream sites of the discharged points. The relatively higher amount of TDS at the downstream sites might be attributed by the high mucilage from coffee processing effluents. The results show that the results of the current study agree with the findings reported by Tadesse M. E. & Haddis A., 2016 and Dejen Yemane Tekle et al., 2015 [15]. However, the effluents quality did appear to be compliant with the regulations of TDS [4]. Thus the parameter indicated that the water was suitable for direct domestic use [10] [11].
The high values of TDS can be toxic to flesh water animals causing osmotic stress and can give increase to obnoxious odors from the decay of organic matter and vulgar smell [15].
The DO levels in the upstream of the rivers water were found within the range  [15]. There was significant difference in overall TSS between the two seasons at 95% confidence level. The difference is attributable to coffee solids waste during coffee processing. Based on the WHO [16] standard and the overall assessment criteria for river water quality [10], the TSS concentrations along all down streams locations/sites were almost above than the acceptable limit, which indicated the pollution of the rivers. Based on the standard limit values, TSS in all sampling points (rivers) should adversely affect the use of water for various purposes [17]. High TSS can cause turbidity in the river and may change the habitat of aquatic microorganisms. concentrations found at downstream of the discharged points could be due to wet coffee effluents discharged without any treatment. However, the effluents qualities appeared to be compliant with the standards. Thus, the chloride parameter indicated that water was appropriate for direct use [19].  There was no significant difference in nitrite recorded in both seasons (wet and dry seasons).
In Kayanza growing ecological zones, the copper values for all the samples in kayanza during dry season did not exceed the limit of detection of AAS. In this case, the coffee effluents from all locations did not contribute to water pollution in studied areas [4]. The concentrations of Cu were within the permissible limit standards and o overall assessment and classification of stagnant and running surface water according to their quality of river water [10] [11].
Copper is acutely toxic to most of forms of aquatic life at relatively low concentrations. Increased quantities of copper make water distasteful to drink. The copper values for all the samples in Kayanza during sampling periods did not exceed the limit of detection of AAS. Lead is a toxic element that accumulates in Open Journal of Applied Sciences the skeletal structures. The toxic effects of Pb to fish decrease with increasing water hardness and dissolved oxygen [20] [21].

Conclusion
Wet coffee processing factories in Kayanza coffee growing ecological zone contain large amounts of organic and nutrient load. This huge untreated wastewater is discharged directly into the nearby pits that are intended to serve as waste stabilization ponds but are neither appropriately constructed to accommodate the generated waste during peak processing time and some wet coffee factories discharged directly their coffee effluent into nearby water bodies. This leads to overflow of raw effluents into natural watercourses and damages the surface waters and aquatic life. The findings show that coffee wastewater discharged without any treatment contributes to the pollution of receiving water bodies. Therefore, the coffee wastewater generated around the rivers was found to have a great negative impact on the receiving water bodies' quality, hence extra care has to be taken in order to protect the receiving water bodies from being polluted. Laws and policies should be enforced to ensure the parameters of the wastewater are within the set standards in order to safeguard the environment.