Biological Systems Engineering

Pius Ndegwa, Ph.D.

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Refereed Journal Articles

 

• Vaddella, V.K., P.M. Ndegwa, H.S. Joo. 2011. Ammonia loss from simulated post-collection storage of scraped and flushed dairy-cattle manure. Biosystems Engineering 110:291-296 (PDF Full Text).
• Pandey, P.K., P.M. Ndegwa, R. Alldredge, M. Pitts. 2011. Efficacies of inocula on the startup of anaerobic reactors treating dairy manure under stirred and unstirred conditions. Biomass and Bioenergy 35:2705-2720 (PDF Full Text).
• Vaddella, V.K., P.M. Ndegwa, A. Jiang. 2011. An Empirical model for ammonium ion dissociation in liquid dairy manure. Trans. of the ASABE 54(3):1119-1126 (PDF Full Text).
• Hristov, A.N., M. Hanigan, A. Cole, R. Todd, T. McAllister, P.M. Ndegwa, A. Rotz.  2011. Ammonia emissions from dairy farms and beef feedlots: A review. Can. J. Anim. Sci. 91:1-35 (PDF Full Text).
• Vaddella, V.K., P.M. Ndegwa, H. Joo, and J.L. Ullman. 2010. Impact of Separating Dairy Cattle Excretions on Ammonia Emissions. J. Environ. Qual. 39:1807-1812 (PDF Full Text).
• Angle, M., A.N. Hristov, A.N., S. Zaman, C. Schneider, P. M. Ndegwa, V.K. Vaddella. 2010. Effect of dietary concentrate on rumen fermentation, digestibility, and nitrogen in dairy cows.  J. Dairy Sci. 93:4211-4222 (PDF Full Text).
• Pandey, P.K., P.M. Ndegwa, R. Alldredge, M. Pitts. 2010. Modeling effects of granules on the start-up of anaerobic digestion of dairy wastewater with Langmuir and Extended Freundlich Equations. Bioprocess and Biosyst Engineering 33:833-845 (PDF Full Text).
• Angle, M., A.N. Hristov, A.N., S. Zaman, C. Schneider, P. M. Ndegwa, V.K. Vaddella. 2010. The effect of ruminally degraded protein on rumen fermentation and ammonia losses from manure in dairy cows.  J. Dairy Sci. 93(4):1625-1637 (PDF Full Text) .
• Hristov, A.N., S. Zaman, M. Vander Pol, P. Ndegwa, L. Campbell, S. Silva. 2009. Nitrogen Losses from Dairy Manure Estimated Through Nitrogen Mass Balance and Chemical Markers. J. Environ. Qual. 38:2438-2448 (PDF Full Text).
• Ndegwa, P.M., V. Vaddella, A.N. Hristov, H.S. Joo. 2009. Measuring concentrations of ammonia in ambient air or exhaust air stream using acid traps. J.  Environmental Quality 38:647-653 (PDF Full Text).
• Joo, H.S., P.M. Ndegwa, M. Shoda, C. Phae. 2008. Bioremediation of oil-contaminated soil using Candida catenulata and foodwaste. Environmental Pollution 156(3):891-896 (PDF Full Text).
• Ndegwa, P.M., A.N. Hristov, J. Arogo, R.E. Sheffield. 2008. A review of ammonia emissions mitigation techniques for concentrated animal feeding operations. Biosyst. Engineering 100(4):453-469 (PDF Full Text).
• Ndegwa, P.M., D.W. Hamilton, J.A. Lalman, H.J. Cumba. 2008. Effects of cycle-frequency and temperature on the performance of anaerobic sequencing batch reactors (ASBRs) treating swine waste. Bioresource Technology 99(6):1972-1980 (PDF Full Text).
• Chowdhury, N., J. A. Lalman, R. Seth, P.M. Ndegwa. 2007. Biohydrogen production by mesophilic anaerobic of glucose in the presence of linoleic acid. Environmental Engineering-ASCE 133(12):1145-1152 (PDF Full Text).
• Ndegwa, P.M., L. Wang, V.K. Vaddella. 2007. Potential strategies for process control and monitoring of stabilization of dairy wastewaters in batch aerobic treatments systems. Process Biochemistry 42(9): 1272-1278 (PDF Full Text).
• Ndegwa, P.M., L. Wang, V.K. Vaddella. 2007. Stabilization of dairy wastewater using limited-aeration treatments in batch reactors. Biosystems Engineering 97(3):379-385 (PDF Full Text).
• Templer J, J.A. Lalman, N. Jing, P.M. Ndegwa. 2006. Influence of C18 long chain fatty acids on hydrogen metabolism. Biotechnology Progress 22(1):199-207 (PDF Full Text).
• Zhu, J., A. Luo, P.M. Ndegwa. 2006. Effect of microbial additives combined with aeration on reduction of nutrients in swine manure. Trans. of the ASABE 49(1):203-280 (PDF Full Text). 
• Hamilton, D.W., I.N. Kourtchev, P.M. Ndegwa, H.J. Cumba. 2006. Methane and carbon dioxide emissions from simulated anaerobic swine manure treatment lagoons under summer conditions. Trans. of the ASABE 49(1):157-165 (PDF Full Text). 
• 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 (PDF Full Text) .
• 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 Eng. 89(2):223-229 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• Ndegwa, P.M. 2004.  Limitations of Orthophosphates Removal during Anaerobic Batch Treatment of Piggery Slurry. Biosystems Engineering 87(2):201-208 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text) .
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• Ndegwa, P.M., J. Zhu, A. Luo. 2002.  Stratification of Solids, Nitrogen and Phosphorus in Swine Manure in Deep Pits Under Slatted Floors.  Bioresour. Techno. 83(3):203-211 (PDF Full Text).
• 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 (PDF Full Text).  
• 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 (PDF Full Text).
• Ndegwa, P.M., J. Zhu, A. Luo. 2002. Effects of Solids Separation and Time on the Production of Odorous Compounds in Stored Pig Slurry. Biosyst. Engineering 81(1): 127-133 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• Zhu, J., A. Luo, Ndegwa, P.M. 2001. Raising pH by Low Level Aeration for Soluble Phosphorus Removal from Swine Manure. Trans. of the ASAE 44:391-396 (PDF Full Text).
• 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 (PDF Full Text) .
• Luo, A., J. Zhu, Ndegwa, P.M. 2001. Phosphorus Transformations in Swine Manure during continuous and intermittent Aeration Processes. Trans. of the ASAE 44(4):967-972 (PDF Full Text).
• Ndegwa, P.M., S.A.Thompson. 2001. Integrating Composting and Vermicomposting in the Treatment and Bioconversion of Biosolids. Bioresource Techno. 76(2):107-112 (PDF Full Text).
• 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 (PDF Full Text).
• Ndegwa, P.M., S.A.Thompson. 2000. Effects of C-to-N Ratio on Vermicomposting of Biosolids.  Bioresource Technology 75(1):7-12 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• 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 (PDF Full Text).
• Ndegwa, P.M., S. A. Thompson, W. C. Merka. 1991. Fractionation of Poultry Litter for Enhanced Utilization. Trans. of the ASAE 34(3):992-997 (PDF Full Text).
  

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