Mwangi Simon Thuku F21/2492/2009 Supervisors : Mr. Orodi Odhiambo - PowerPoint PPT Presentation

UNIVERSITY OF NAIROBI

ENVIRONMENTAL & BIOSYSTEMS ENGINEERING

Design of a biological slaughterhouse wastewater treatment system (Using an anaerobic baffle reactor – constructed wetland system) < case study of Kiserian Slaughterhouse>

Mwangi Simon Thuku

F21/2492/2009

Supervisors : Mr. Orodi Odhiambo

Eng. D. A. Mutuli

Approximated slaughterhouse waste content and NEMA standards for disposal into the environment

Johns et al., 1995; Manjunath et al., 2000, NEMA

BACKGROUNDCont’d

Treatment Options

• Anaerobic treatment + activated sludge
• Anaerobic treatment + contact aeration
• Activated sludge + chemical coagulation
• Contact aeration + chemical coagulation.

• This waste water flows to R. Kiserian and eventually gets to Kiserian Dam.
• This causes eutrophication and anoxia in the water bodies.
• Waste from slaughterhouses also leads to air and soil pollution

Pre- treated Wastewater getting into the streams

Site Analysis

• Kiserian is a settlement in Kajiado county
• Habitants are mainly pastoralist community
• Warm and Temperate climate.
• Rainfall =833mm
• Temperature = 17.8

Overall objective

To design a biological slaughterhouse wastewater treatment systemSpecific Objectives

To analyze the amount and the content of wastewater

To establish pertinent parameters for design of a biological slaughterhouse waste water treatment system.

To use the parameters from (ii) to size the baffle reactor and the constructed wetland.

• Survey work
• Carrying out tests
• Determination of System Design Parameters
• Making detailed engineering drawings

Literature review

• Treatment Process ( primary, secondary and tertiary treatment)
• Why anaerobic?
• Anaerobic Baffle reactor (improved septic tank)
• Constructed Wetland

Methodology

Survey

Soil and waste water sampling

Laboratory tests (soil & waste water)

Determining the efficiency of ABR

ABR volume determination

Result analysis

Designing the wetland

Structural design of the ABR

Theoretical Framework

Chemical oxygen demand,

Biochemical Oxygen Demand, BOD5,mg/L =

Sasse (1998), Wanasen (2003), Foxon et al., (2004) etc

Results

Results Cont’d

Leslie C.P. et al, 1999

Results Cont’d

Qi = 14.5m3/d

y = 0.7 m

As =

126.22 m2

t = 1.85 days

width = 7.94 m

dh = 0.01 x 15 = 0.15m

Length = 2 x 9 = 16 m

slope is taken to be 1.5

Drawings

Drawings

Drawings

Drawings

Drawings

Conclusion

• Objectives of the design project were met.
• slaughterhouse wastewater was observed to have high content of waste.
• The BOD5 removal efficiency for the ABR was found to be 90% (i.e. from 936.25mg/l to 93.625mg/l) with a HRT of 2.38days. The organic lading in the ABR was found to be 1.314 kg COD/m3.d (should range between 1 – 3 kg COD/m3.d).
• The CW reduced the concentration of nitrates in the waste water from 141.5 mg/l to 100 mg/l and the BOD from 93.625mg/l to 15.62mg/l.
• System was found to have a 98.4% BOD reduction

Recommendations

• The first compartment of the ABR should be modified and increased in size to trap as much solids as possible.
• The ABR should be made air tight and a system to improve/increase the pressure of the biogas in the reactor to allow gas collection otherwise the first compartment can be constructed in such a way that it has a gas holder and made airtight (shape of a fixed dome).
• A gradient should be created between the ABR and the CW so as to utilize gravity as the driving force.
• Wastewater monitoring/ testing should be done on a regular basis in order to ensure that the content of waste flowing to the stream conforms with the NEMA standards and as a way of monitoring the performance of the system.

References

• Muench, E. (2008): Overview of anaerobic treatment options for sustainable sanitation systems. In: BGR Symposium "Coupling Sustainable Sanitation and Groundwater Protection".
• Bachmann, A., Beard, VL. and McCarty, PL. (1985). Performance Characteristics of the Anaerobic Baffled Reactor. Water Research 19 (1): 99–106.
• Sergio S. Domingos (2011), Thesis on Vertical flow constructed wetlands for the treatment of inorganic industrial wastewater, Murdoch University WA, Australia.
• Morel A. and Diener S. (2006). Greywater Management in Low and Middle-Income Countries, Review of diff erent treatment systems for households or neighbourhoods. Swiss Federal Institute of Aquatic Science and Technology (Eawag). Dubendorf, Switzerland.
• Nijaguna B.T. (2002), Biogas Technology, New Age International (P) Limited, New Delhi.

References

• Rustige H &Platzer Chr. (2000),Nutrient Removal in Subsurface Flow Constructed Wetlands for Application in sensitive Regions in: Proceedings – 7th Int. Conf. On Wetland Systems for Water Pollution Control, Orlando, USA
• Leslie Grady .C, Glen .T, (1999), Biological Wastewater treatment, 2nded, Maral Dekker ,Inc, New York
• Foxon KM, Pillay S, Lalbahadur T, Rodda N, Holder F, Buckley CA (2004) The anaerobic baffled reactor(ABR): An appropriate technology for on-site sanitation. Water South Africa 30, 44-50.
• Lawrence A.W. and McCarty p.L (1970): Unified basis for biological Treatment Design and Operation. J. Sanit. Eng. Div., Am. Soc. CivEngrs.
• Walter R.H., Shermah R.M. and Downing D.L. (1974): Reduction in Oxygen demand of abattoir effluent by Precipitation with metal. J. Agric. FdChem

THANK

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