Biological Systems Engineering

Pius Ndegwa, Ph.D.

Refereed Journal Articles

 

Ndegwa, P.M., D.W. Hamilton, J.A. Lalman, H.J. Cumba. 2005. Optimization of Anaerobic Sequencing Batch Reactors (ASBRs) Treating Dilute Swine Slurries.Trans. of the ASAE 48(4): 1575-1583.

Zhu J., Luo, A., Zhou, Y., Ndegwa, P.M., Schmidt, D.R. 2004. The Age Effect of Dairy Feedlots on Manure Nutrient Seepage in Loam Soils. Biosystems Engineering 89 (2): 223-229.

Ndegwa, P.M., 2004.  Solids Separation Enhances Reduction of Organic Strength of Swine Manure Subjected to Aeration Treatments. Trans. of the ASAE 47(5):1659-1666.

Zhu, J., A. Luo, Y. Zhou, Ndegwa, P.M., D. Schmidt. 2004. Nutrient Seepage from Operating Turkey Buildings with a Litter System.  Water, Air, and Soil Pollution 155(1-4): 87-101.

Ndegwa, P.M. 2004.  Limitations of Orthophosphates Removal during Anaerobic Batch Treatment of Piggery Slurry. Biosystems Engineering 87(2):201-208.

Zhu, J., Ndegwa, P.M., Z. Zhang. 2004. Manure Sampling Procedures and Nutrient Estimation by the Hydrometer Method for Gestation Pigs. Bioresource Technology 92(3):243-250.

Ndegwa, P.M., J. Zhu, A. Luo. 2003.  Effects of Bioreactor Temperature and Time on Odor-Related Parameters in Aerated Swine Manure Slurries.  J. Environ. Technology 24(8): 1007-1016.

Ndegwa, P.M., J. Zhu, A. Luo, D.W. Hamilton. 2003. Enhanced Phosphorus Removal from Swine Manure in Aerated Batch Reactors. Trans. of the ASAE 46(3): 797-803.

Zhu, J., Ndegwa, P.M., A. Luo. 2003. Temperature Effects on Pig Manure under Low-Level Batch Aeration. The International Journal of Environ. Studies 60(5): 523-533.

Ndegwa, P.M., J. Zhu. 2003. Sampling Procedures for Piggery Slurry in Deep Pits for Estimation of Nutrient Content.  Biosystems Engineering 85(2): 239-248.

Ndegwa, P.M. 2003.   Solids Separation Coupled With Batch-Aeration Treatment For Odor Control From Liquid Swine Manure.  J. Environ. Sci. Health B38(5): 631-643.

Zhu, J., Z. Zhang, Ndegwa, P.M.. 2003. Using a Soil Hydrometer to Measure the Nitrogen and Phosphorus Contents in Pig Slurries. Biosystems Engineering 85(1): 121-128.

Ndegwa, P.M., J. Zhu, A. Luo. 2003. Discussions and Closure to “Effects of Solids Levels and Chemical Additives on Removal of Solids and Phosphorus in Swine Manure”.  J. Environ. Eng.-ASCE 129(5): 485-487.

Zhu, J., Ndegwa, P.M., Z. Zhang. 2003. Settling Characteristics of Nursery Pig Manure and Nutrient Estimation by the Hydrometer Method. J. Environ. Sci. Health B38(3): 379-390.

Zhu, J., A. Luo, Y. Zhou, Ndegwa, P.M., D. Schmidt.  2002. Barn Age Impact on Nutrient Leaching from Turkey Barns Built on Clay Loam Soils. Trans. of the ASAE 45(6): 1971-1976.

Ndegwa, P.M., J. Zhu, A. Luo. 2002.  Influence of temperature and time on phosphorus removal in swine manure during batch aeration.  J. Environ. Sci. Health B38(1): 73-87.

Luo, A., J. Zhu, Ndegwa, P.M.. 2002. Influence of anaerobic pre-conditioning on phosphorus removal in swine manure by aeration.  J.  Water, Air, and Soil Pollution 140(1-4): 219-230.

Ndegwa, P.M., J. Zhu, A. Luo. 2002.  Stratification of Solids, Nitrogen and Phosphorus in Swine Manure in Deep Pits Under Slatted Floors.  Bioresource Techno. 83(3): 203-211.

Zhu, J., Ndegwa, P.M., A. Luo. 2002. Bacterial Responses to Temperature during Aeration of Pig Slurry. J. Environ. Sci. Health B37(3): 265 - 275.  

Luo, A., J. Zhu, Ndegwa, P.M.. 2002. Removal of Carbon, Nitrogen, and Phosphorus in Pig Manure by Continuous and Intermittent Aeration at Low Redox Potentials. Biosystems Eng. 82(2): 209-215.

Ndegwa, P.M., J. Zhu, A. Luo. 2002. Effects of Solids Separation and Time on the Production of Odorous Compounds in Stored Pig Slurry.    Biosystems Engineering 81(1): 127-133.

Thompson, S.A, Ndegwa, P.M., W.C. Merka, A. B. Webster. 2001. Reduction in Manure Weight and Volume Using an In-House Layer Manure Composting System under Field Conditions.  Applied Poultry Research 10(3): 255-261.

Zhu, J., Ndegwa, P.M., A. Luo. 2001. Effect of solid-liquid separation on BOD and VFAs in swine manure. J. Environmental Technology 22(10): 1237-1243.

Ndegwa, P.M., J. Zhu, A. Luo. 2001.  Effect of Batch Aeration-Treatment on the Solubility of Phosphorus in Pig Manure.  J. Agricultural Engineering Res. 80(4): 365-371

Zhu, J., A. Luo, Ndegwa, P.M.. 2001. Raising pH by Low Level Aeration for Soluble Phosphorus Removal from Swine Manure. Transactions of the ASAE 44(2): 391-396.

Ndegwa, P.M., J. Zhu, A. Luo. 2001.  Effects of Solids Levels and Chemical Additives on Removal of Solids and Phosphorus in Swine Manure.  J. Environmental Engineering-ASCE 127(12): 1111-1115.

Luo, A., J. Zhu, Ndegwa, P.M.. 2001. Phosphorus Transformations in Swine Manure during continuous and intermittent Aeration Processes. Transactions of the ASAE 44(4): 967-972.

Ndegwa, P.M., S.A.Thompson. 2001. Integrating Composting and Vermicomposting in the Treatment and Bioconversion of Biosolids. Bioresource Technology 76(2): 107-112.

Zhu, J., A. Luo, Ndegwa, P.M.. 2001. The Effect of Limited Aeration on Swine Manure Phosphorus Removal.  J. Environ. Sci. Health B36(2): 209-218.

Ndegwa, P.M., S.A.Thompson. 2000. Effects of C-to-N Ratio on Vermicomposting of Biosolids.  Bioresource Technology 75(1): 7-12.

Zhu, J., Ndegwa, P.M., A. Luo. 2000. Changes in Swine Manure Solid Components During Storage Relating to Separation Efficiency. Applied Engineering in Agriculture 16(5): 571-575.

Ndegwa, P.M., S. A. Thompson, W. C. Merka. 2000.  A Dynamic Simulation Model of in-situ Composting of Caged-Layers’ Manure. Compost Sci. & Utilization 8(3): 190-202.

Ndegwa, P.M., S.A.Thompson, K.C. Das. 1999. Effects of Stocking Density and Feeding Level on Vermicomposting of Biosolids. Bioresource Technology 71(1): 5-12.

Ndegwa, P.M., S. A. Thompson, W. C. Merka. 1991. Fractionation of Poultry Litter for Enhanced Utilization. Transactions of the ASAE 34(3): 992-997.

 

 

"Something in the Air"

 

Dr. Pius Ndegwa

Biological Systems Engineering
Washington State University
LJSmith 202, P.O. Box 64120
Pullman, Wasington 99164-6120

Phone:
509 335-8167

Fax:
509 335-2722

Electronic Mail:
ndegwa@wsu.edu

 

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