This study examined the life cycle and environmental impacts of managing green waste in Fresno, California. Preliminary results found that the compost produced may be unsuitable for crop production due to low nutrient contents. Greenhouse gas emissions were also found to be higher on-site during composting. Further analysis is needed to understand the trade-offs between composting and other waste management processes, as well as the overall environmental costs and effectiveness of composting in Fresno. The study aims to assess compost quality, greenhouse gas emissions, and environmental costs to help inform green waste management in the region.

1. Preliminary Inquiry of Life Cycle Analysis of Green Waste in Fresno
Mohan B. Dangi, Ph.D.1, Cory D. Robbins2, Sergio Moreno, Jr.3, Erika J. Mey2, Nicole N. Hoke2, Raquel A.
Perez2, Rosamaria Herrera2, Leonel Campos4
1Assistant Professor, Department of Geography and City & Regional Planning, California State University, Fresno, mdangi@csufresno.edu
2Department of Geography and City & Regional Planning, California State University, Fresno
3Department of Biology, California State University, Fresno
4Department of Earth and Environmental Sciences, California State University, Fresno
Introduction
Green Valley Recycling (GVR) in Fresno,
California handles 102,000 tons of green waste per
annum and of which 55,000 tons is sent to
Kochergen Farms Composting (KFC) and 47,000
tons is delivered to biomass incinerator. This study
used life cycle analysis (LCA) approach to examine
the trade-offs and environmental costs associated
with managing green waste in Fresno.
Discussion of Results
The organic matter, C:N, and moisture content
were lower than recommended; pH was within the
range; and EC5 was two times higher. See Table 1.
Table 1. Standard parameters measured as received for compost.
The NPK values were much lower than 2%, 0.3%,
and 0.8% reported by Cogger et al. (2002). See
Table 2.
Table 2. Percentage of nutrients found in windrow composting.
The emissions seem to be dominated by alcohols,
which is consistent with literature. We did a couple
of upwind samples and a couple from the middle
of the site, and found out about 0.5 ppm more
VOCs (not including methanol) on site (which is
substantial). See Figs. 1-2. Methanol is very strange.
Both of the upwind measurements indicated about
10 ppm of methanol in the air. Environmental costs
of operating GVR and KFC are being analyzed.
Fig. 1. Emission from Compost for Flag 2. Fig. 2. Emission from Compost for East Face.
Conclusions
Preliminary results hint that compost produced
from green waste in Fresno may be unfit for crop
production, while it may be used for Grade B or
lower applications. The finished product lacks
nutrient contents, and potentially contributes to
greenhouse gas emission. More study is required
to understand the trade-offs among different
processes within composting, overall cost
effectiveness of composting, and its net impact to
the environment.
Acknowledgements
Dr. Alam Hasson, Dept. of Chemistry, CSU, Fresno
Green Valley Recycling
Kochergen Farms Composting
References
• Cogger, C., Bary, A., and Sullivan, D.M. 2002.
Fertilizing with yard trimmings. Washington
State University Cooperative Extension.
• Diaz, L., Savage, G.M., and Golueke, C.G. 2002.
Composting of Municipal solid wastes. (In
Tchobanoglous, G. and Kreith, F. (2nd ed.),
Handbook of solid waste management. New
York City, NY: McGraw-Hill. p. 12.1-12.70.)
• http://www.mapsofworld.com/usa/fresno-
city-map.html.
Objectives
• Understand quality and usefulness of compost.
• Study greenhouse gas emission from compost.
• Assess environmental cost of composting in
Fresno.
Methods
Season specific characterization of green waste
was followed by monitoring of windrow piles.
Laboratory analyses of compost were also utilized.
Parameters 21-Feb-13 5-Jun-13 18-Jul-13 16-Sep-13 Average
Moisture content (%) 40.5 29.2 15.1 30 28.7
pH 7.71 7.52 6.99 7.1 7.3
Bulk density (lbft-3) 51 58 56 53 54.5
EC5 (mmhoscm-1) 4.2 4.7 5.7 5.7 5.1
Organic matter (%) 14.4 16.3 19.6 18.5 17.2
C/N ratio 12 12 10 14 12
Nutrients 21-Feb-13 5-Jun-13 18-Jul-13 16-Sep-13 Average
N 0.65 0.78 0.93 0.62 0.75
P2O5 0.31 0.36 0.44 0.27 0.35
K2O 0.65 0.63 0.82 0.61 0.68