Analysis of the Amount of Gas Generation for the Amount of Organic Matter Removal in Accordance with the Merge Ratio of Livestock Manure and Food Waste in a Single-Phase Anaerobic Digester

A single-phase reactor was applied to food waster digestion for hydrogen production in order to test its feasibility. Different solid retention time (SRT) and pH adjustment modes were tried in a series of semi-continuous experiments. The results showed that it was necessary to take some precautions including a long SRT and a proper pH adjustment mode so as to avoid the excessive acidification in single-phase digesters. When lime milk was added into the digester to adjust pH to about 7 once a day, the food waste digester, which had a SRT of 20 days and a feed concentration of 4%, can produce hydrogen steadily. The hydrogen content was 27.6-51.3% and the degradation rate of food waste organic matter was 54%.

Download Full-text

A Comparison of Two-Stage and Traditional Co-Composting of Green Waste and Food Waste Amended with Phosphate Rock and Sawdust

Sustainability ◽

10.3390/su13031109 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1109

Author(s):

Edgar Ricardo Oviedo-Ocaña ◽

Angélica María Hernández-Gómez ◽

Marcos Ríos ◽

Anauribeth Portela ◽

Viviana Sánchez-Torres ◽

...

Keyword(s):

Organic Matter ◽

Product Quality ◽

Food Waste ◽

Phosphate Rock ◽

Pilot Scale ◽

Two Stage ◽

Green Waste ◽

Wet Weight ◽

Two Phases

The composting of green waste (GW) proceeds slowly due to the presence of slowly degradable compounds in that substrate. The introduction of amendments and bulking materials can improve organic matter degradation and end-product quality. However, additional strategies such as two-stage composting, can deal with the slow degradation of green waste. This paper evaluates the effect of two-stage composting on the process and end-product quality of the co-composting of green waste and food waste amended with sawdust and phosphate rock. A pilot-scale study was developed using two treatments (in triplicate each), one being a two-stage composting and the other being a traditional composting. The two treatments used the same mixture (wet weight): 46% green waste, 19% unprocessed food waste, 18% processed food waste, 13% sawdust, and 4% phosphate rock. The traditional composting observed a higher degradation rate of organic matter during the mesophilic and thermophilic phases and observed thermophilic temperatures were maintained for longer periods during these two phases compared to two-stage composting (i.e., six days). Nonetheless, during the cooling and maturation phases, the two treatments had similar behaviors with regard to temperature, pH, and electrical conductivity, and the end-products resulting from both treatments did not statistically differ. Therefore, from this study, it is concluded that other additional complementary strategies must be evaluated to further improve GW composting.

Download Full-text

Life Cycle Assessment of Bioplastics and Food Waste Disposal Methods

Sustainability ◽

10.3390/su13126894 ◽

2021 ◽

Vol 13 (12) ◽

pp. 6894

Author(s):

Shakira R. Hobbs ◽

Tyler M. Harris ◽

William J. Barr ◽

Amy E. Landis

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Anaerobic Digestion ◽

Waste Management ◽

Food Waste ◽

Energy Demand ◽

Anaerobic Digester ◽

Management Scenarios ◽

Cumulative Energy ◽

Cumulative Energy Demand

The environmental impacts of five waste management scenarios for polylactic acid (PLA)-based bioplastics and food waste were quantified using life cycle assessment. Laboratory experiments have demonstrated the potential for a pretreatment process to accelerate the degradation of bioplastics and were modeled in two of the five scenarios assessed. The five scenarios analyzed in this study were: (1a) Anaerobic digestion (1b) Anaerobic digestion with pretreatment; (2a) Compost; (2a) Compost with pretreatment; (3) Landfill. Results suggested that food waste and pretreated bioplastics disposed of with an anaerobic digester offers life cycle and environmental net total benefits (environmental advantages/offsets) in several areas: ecotoxicity (−81.38 CTUe), eutrophication (0 kg N eq), cumulative energy demand (−1.79 MJ), global warming potential (0.19 kg CO2), and human health non-carcinogenic (−2.52 CTuh). Normalized results across all impact categories show that anaerobically digesting food waste and bioplastics offer the most offsets for ecotoxicity, eutrophication, cumulative energy demand and non-carcinogenic. Implications from this study can lead to nutrient and energy recovery from an anaerobic digester that can diversify the types of fertilizers and decrease landfill waste while decreasing dependency on non-renewable technologies. Thus, using anaerobic digestion to manage bioplastics and food waste should be further explored as a viable and sustainable solution for waste management.

Download Full-text