Diversion Of Organic Waste Research Articles

Site Suitability and Air Pollution Impacts of Composting Infrastructure for California's Organic Waste Diversion Law.

California's organic waste diversion law, SB 1383, mandates a 75% reduction in organics disposal by 2025 to reduce landfill methane emissions. Composting will likely be the primary alternative to landfilling, and 75-100 new large-scale composting facilities must be sited in the state to meet its diversion goal. We developed a strategy for evaluating site suitability for commercial composting by incorporating land-use, economic, and environmental justice criteria. In our Baseline scenario, we identified 899 candidate sites, and nearly all are within a cost-effective hauling distance of cropland and rangelands for compost application. About half of sites, mostly in rural areas, are not within a cost-effective collection distance of enough municipal organics to supply an average-sized facility. Conversely, sites near cities have greater access to organics but cause greater health damages from ammonia and volatile organic compounds emitted during the composting process. The additional required composting capacity corresponds to $266-355 million in annual damages from air pollution. However, this excludes avoided emissions from landfilling, and damages could be reduced by 56% if aerated static piles are used instead of windrows. Siting a higher number of smaller decentralized facilities could also help equally distribute air pollution to avoid concentrating burdens in certain communities.

Double-Stage Anaerobic Digestion for Biohydrogen Production: A Strategy for Organic Waste Diversion and Emission Reduction in a South African Municipality

Landfilling of organic waste poses a significant environmental threat, heavily contributing to climate change. The diversion of waste is imperative, but pathways to implementing alternative waste management strategies are needed. Double-stage anaerobic digestion has been identified as a potential technique that can reduce greenhouse gas emissions and diminish the amount of waste landfilled. Still, further research is needed before its implementation at the municipal level. This paper explored the potential insertion of double-stage anaerobic digestion into the portfolio of alternative treatment methods using the case study of the eThekwini Municipality in Durban, South Africa, by proposing a source-separation waste management scheme and forecasting the organic waste generation for a 24-year timeframe until 2050. The WROSE model has been identified as the ideal tool for the analysis. A new scenario, including double-stage anaerobic digestion, has been introduced in WROSE after developing a country-specific emission factor. The technology has been assessed against similar techniques, namely anaerobic digestion and composting, according to the environmental indicators included in WROSE. Compared with the business-as-usual scenario and three other alternatives, the new scenario proved to be the second-most effective (−282% versus business-as-usual) after anaerobic digestion (−291%) in reducing climate-altering emissions, achieving analogous waste diversion rate (10.09%), landfill airspace (1,653,705 m3), and monetary savings (3.8 billion Rand) compared to composting and anaerobic digestion.

Food and organic waste diversion in industrial, commercial, and institutional (IC&I) sectors: A Canadian pilot project

The purpose of this study was to assess the impacts of a pilot project convened by the Circular Innovation Council that collected source-separated organic waste and donatable food from industrial, commercial, and institutional (IC&I) waste generators in a Canadian community. These sectors usually do not receive municipal source-separated organics collection services, and there is little publicly available data on the amounts of organic waste generated in these sectors. In the first year, 53 businesses participated in the pilot project, although some entered or left the project during this time. Participating businesses were provided with green bins to source-separate their food and organic waste and were provided free collection services once a week during the first phase of the pilot. Participants were also supported in donating surplus food to local organizations. We observed that in its first year of operation, the pilot diverted 230,637 kg of food / organic waste from landfill and recovered the equivalent of 39,447 meals (at an estimated value of $131,803.76). We estimated that the long-term care / hospital sub-sector and grocery stores generated the highest amounts of food / organic waste. In its first year, the pilot project averted 182,000 kg of emissions from landfill through the donation of surplus food and 2,360,000 kg of emissions through the diversion of food and organic waste to compost and anaerobic digestion. Supporting dedicated food recovery and organics collection services to IC&I generators therefore has the potential to reduce large amounts of greenhouse gas emissions, and to provide food for emergency food systems.

Environmental Impact Assessment of a Solar Drying Unit for the Transformation of Food Waste into Animal Feed

Food waste valorization via its transformation into animal feed is a viable alternative for improving food security and the diversion of organic waste from landfills. The manuscript presents the environmental impact assessment of the construction and operation of a novel solar food waste drying unit on the island of Crete in Greece, which is treating food waste from hotels. Life cycle assessment is utilized for the impact assessment. The results indicate a total carbon footprint of approximately 217.5 kg CO2 eq. per ton of treated food waste. In conclusion, the operation phase is the major contributor to the environmental impacts, due to the utilization of electricity.

Transitioning towards a circular bioeconomy in South Africa: Who are the key players?

The transition towards a circular economy is becoming a priority in many countries globally. However, the circular bioeconomy has received relatively less attention. In South Africa, the valorisation of organic waste is a priority area as demonstrated by national goals to divert organic waste from landfill. To support the growth of the organic waste value chain it is important to gain an understanding of the different value chain actors and their activities. Through a series of semi-structured interviews across the industry, this paper unpacks the organic waste value chain including the roles of different actors and the interlinkages amongst them. Interviewed actors were those involved in the waste treatment sector, including consultants, composters and technology providers and installers. The value chain is characterised by a number of partnerships, including sub-contracting and outsourcing, which enable value chain actors to offer services that they do not necessarily have the in-house skills or capacity to deliver on their own. The majority of actors were not directly engaged in activities related to the treatment of waste, with many of them engaging in support activities to facilitate the treatment of waste. This finding may be attributed to the fact that support activities have relatively lower barriers to entry. This has the potential to create a bottleneck, in which there will be limited capacity for waste treatment as new entrants opt for engaging in support activities. Greater investment is needed from both private and public sources in the waste treatment sector, including support for new entrants. This investment will help enable the country to meet its goals for organic waste diversion whilst contributing to job creation.Significance: The majority of participants in the organic waste value chain were engaged in support activities. The organic waste value chain is characterised by a series of partnerships. Greater investment is needed for the development of waste treatment facilities.

Fertilizer demand and potential supply through nutrient recovery from organic waste digestate in California

Diversion of organic waste from landfills offers an opportunity to recover valuable nutrients such as nitrogen and phosphorus that are typically discarded. Although prior research has explored the potential for buildout of anaerobic digestion (AD) infrastructure to treat organic waste and generate energy, a better understanding is needed of the nutrient recovery potential from the solid and liquid byproducts (digestate) resulting from AD of these waste streams. We quantified the system-wide mass of nutrients that can potentially be recovered in California by integrating current and potential future AD facilities with existing nutrient recovery technologies. Based on a profitable build-out scenario for AD, the potential for nitrogen and phosphorus recovery by mass was greatest from municipal sewage sludge. The nutrient recovery (% total mass) was determined for three different end products for the combined organic waste streams: liquid fertilizer [38% of the total recovered nitrogen (TN)], struvite [50% TN, 66% total phosphorous (TP)], and compost (12% TN, 34% TP). Based on the profitable build-out scenario of AD facilities in California, the recovered nutrients would offset an estimated 11% of TN and 29% of TP of in-state synthetic fertilizer demand, whereas a scenario in which all technically recoverable biomass is collected and treated could offset 44% of TN and 97% of TP demand.

Quantification of climate change mitigation potential at Novi Sad landfill

Unsanitary landfills and inadequate waste management system represent the 3rd largest global anthropogenic source of methane emissions in the environment. Waste management system in Novi Sad, the second largest city in Serbia, significantly contributes to the national carbon footprint. Unsanitary Municipal solid waste landfill in Novi Sad receives and deposits mixed waste without any treatment, thus causing the organic waste to biodegrade within the landfill body, and produce and emit the landfill gas (mostly CH4 and CO2) in the environment. Other potential sources of greenhouse gas emissions from waste management system include vehicles used for waste collection, machinery used at the landfill and landfill fires. The purpose of this study is to determine total baseline emissions of relevant greenhouse gases from the waste management system in Novi Sad, and to estimate and quantify the emission reduction potential for defined organic waste treatment scenario. The potential scenarios for organic waste diversion and treatment from the landfill include composting, anaerobic digestion, mechanical biological treatment, waste to energy, etc. Quantification of baseline emissions and climate change mitigation potential are estimated using the Solid Waste Emissions Estimation Tool, the model developed by Climate and Clean Air Coalition.

Processing of biomethane for electricity production as a sustainable way to treat municipal organic solid waste: A case study of the Corumbataí river basin region

This study proposed action scenarios for urban solid waste management in six municipalities in the Corumbataí River Basin. The operating scenarios were designed for organic waste treatment and for the shared disposal of urban solid waste. Six municipalities were studied, five of which had less than 30,000 inhabitants (Analândia, Charqueada, Corumbataí, Ipeúna, and Santa Gertrudes). In addition, Rio Claro had 199,000 inhabitants. Thus, the transport and transshipment stages, general infrastructure, and final disposal in landfills were analyzed. Further, the three scenarios for organic waste treatment were conducted separately. The items and the cost of implementation were estimated for decentralized composting, centralized composting, and biomethanization of waste with electricity recovery. The biomethanization scenario included the commercialization of electricity, so it generated revenues that decreased costs. This cost reduction was especially notable in the last years of the project when the goals of diversion of organic waste through selective collection were higher. The results suggested that the investigated scenarios could improve organic waste treatment and that the biomethanization scenario with electricity generation presented lower average costs per inhabitant than the centralized and decentralized composting scenarios.

Participation in residential organic waste diversion programs: Motivators and optimizing educational messaging

Participation in residential organic-waste-diversion-programs (OWDP) represents an individual-level behaviour with significant environmental benefits, including lowering greenhouse gas emissions. This study of 2621 Niagara, Canada, residents sought to understand the attitudinal and sociodemographic drivers of participation and non-participation in OWDP. Additionally, we examined the impact of messaging about the benefits of OWDP on likelihood of future participation while varying the frame and perceived source of information. Participants reported environmental factors as the main motivators for OWDP involvement, while non-participants cited smell, inconvenience and cost as the most salient barriers. Several sociodemographic and knowledge factors predicted participation, as did strong recognition of the anthropogenic origins of climate change. Forty two percent of non-participants were more likely to participate after receiving the educational message, but this did not vary with information source nor a social-norm frame. These findings inform theory around pro-environmental behaviour and provide actionable information for education campaigns aimed at promoting OWDP.

Quantifying the Farmland Application of Compost to Help Meet California's Organic Waste Diversion Law.

California's landmark waste diversion law, SB 1383, mandates the diversion of 75% of organic waste entering landfills by 2025. Much of this organic waste will likely be composted and applied to farms. However, compost is expensive and energy intensive to transport, which limits the distance that compost can be shipped. Though the diversion of organic waste from landfills in California has the potential to significantly reduce methane emissions, it is unclear if enough farmland exists in close proximity to each city for the distribution of compost. To address this knowledge gap, we develop the Compost Allocation Network (CAN), a geospatial model that simulates the production and transport of waste for all California cities and farms across a range of scenarios for per capita waste production, compost application rate, and composting conversion rate. We applied this model to answer two questions: how much farmland can be applied with municipal compost and what percentage of the diverted organic waste can be used to supplement local farmland. The results suggest that a composting system that recycles nutrients between cities and local farms has the potential to play a major role in helping California meet SB 1383 while reducing state emissions by -6.3 ± 10.1 MMT CO2e annually.

The role of management instruments in the diversion of organic municipal solid waste and phosphorus recycling

Organic waste, which contains essential plant nutrients such as phosphorus, constitutes 30%–50% of municipal solid waste in developed countries. Unfortunately, much of this resource is buried in landfills or incinerated. Many jurisdictions have, therefore, adopted the diversion of organic waste and the recycling of nutrients as policy goals. We used data sets from Europe and Ontario, Canada, to explore the impact of socio-economic and management factors on the rates of organic waste diversion and examined the effect of this diversion on phosphorus recycling. Organic diversion rates were highly correlated with income in Europe and with infrastructure, such as source-separated organic waste collection, in Ontario. Significant correlations were also observed between diversion rates and the use of policy instruments such as economic incentives, legislative organic waste bans, and curbside bag limits. We estimated that 39%–63% of the phosphorus in diverted organics is returned to arable land. Ultimately, we found that although socio-economic factors influence the success of organic waste diversion, policies, accessible infrastructure, economic incentives, and legislative requirements can be leveraged to improve the recycling rate of organic waste and the nutrients they contain.

Impact of organic waste composition on life cycle energy production, global warming and Water use for treatment by anaerobic digestion followed by composting

In response to significant organic waste generation, environmental policies are increasingly mandating diversion of organic waste from landfills and promoting alternative management practices to produce energy and reduce greenhouse gas emissions (GHG). Anaerobic digestion and composting are organic waste treatment alternatives, however, both practices require careful management to prevent similar environmental impacts as landfills. A model was developed to assess the impact of anaerobic digestion followed by composting of food waste and green waste mixtures on net energy production, global warming potential and scarce water use. The model included the ability to vary the initial organic waste composition, decomposition kinetics and treatment time. Energy needs for composting aeration and water pumping, and water use decreased as anaerobic digestion time increased. Composting water use savings for an organic waste anaerobically digested for 90 days prior to composting compared to zero days prior to composting ranged between 25%–53% for different organic waste compositions (from 1:0 to 0:1 green waste to food waste ratios), and energy use savings for composting aeration and water pumping ranged between 15%–17% and 24%–54%, respectively, for the same conditions. For an anaerobic digestion pretreatment time of 30 days prior to composting, the analysis predicted scarce water use to be 0.31–1.09 m3 swe/Mg waste, primary energy use to be −168.5–298.3 MJ/Mg waste, and global warming potential to be 8.1–26.4 kg CO2e/Mg waste. The results will help inform the design and maintenance of waste treatment in resource-limited environments.

Dynamic simulation of phosphorus flows through Montreal’s food and waste systems

Phosphorus (P) is an important nutrient, essential to plant growth and agricultural production, however it can also act as an aquatic pollutant. Anthropogenic activities have impacted global P flows—causing increased mobilization of P to waterways and accumulation of P in landfills. Cities play a unique role in P management because they tend to concentrate demand for P-rich products and subsequent waste production. After developing a substance flow analysis of current P flows in Montreal, we use a system dynamics model to explore the flows of P on the island from 2008 to 2050 under four scenarios. The scenarios are based on existing trends, impending policies, and possible social change. We found that presently over 80% of P imported onto the island ends up in landfill, another 17% flows to the Saint Lawrence River, and less than 3% is available for recycling. There is significant potential to recover P from both wastewater and solid organic waste on the island of Montreal, and to reduce P flows to landfill by up to 95%. Given that existing policies in Montreal support organic waste diversion and wastewater treatment, information gained through our study can be utilized to make P policy and management decisions that fit readily into these current policies. This study shows leverage points where Montreal has the most potential to improve its P management, reducing the use of synthetic fertilizers and reducing P pollution. Furthermore, this model can be used to guide future research analyzing P flows in urban settings.

Overcoming barriers to codigestion

Codigestion of organic waste with municipal wastewater sludge is growing rapidly. It has many benefits, including diversion of organic waste from landfills, increased renewable energy from biogas production, and potential for revenue from tipping fees. However, there are still barriers to greater widespread application of codigestion. Economics, need for collaboration between utilities, impacts on wastewater application, unsupportive regulations and risks to core wastewater treatment business are obstacles that slow wider adoption of codigestion throughout the world. The research presented analyzes the economic impacts of codigestion, predicts the additional biogas production, and determines the allowable organic loading rate and fats oils and grease (FOG) addition for stable digestion operation. The economic impacts were analyzed on a life cycle cost basis and presented in terms of required tipping fees for different organic wastes, electric rates and residuals handling costs. Standard biochemical methane potential tests were conducted to estimate biogas production from various organic wastes. The specific energy loading rate (SELR) was used to express the allowable organic loading rate. Results from the economic analysis showed that codigestion using existing digesters at a municipal water reclamation facility is more economical than building new digesters. Codigestion was more economical at facilities with high electricity costs and low cost of residuals. Tipping fees for receiving organic waste would be required to offset the net cost of codigestion for wastes other than FOG. There was a net positive economic benefit of receiving FOG without a tipping fee. The upper limit of FOG for stable digestion was found to be 60 percent of the feed by chemical oxygen demand (COD). Stable digestion can be achieved with an SELR of less than 0.25 kgCOD/day/kgVS. The SELR accounts for the strength or energy content of the organic feed measured in COD. It was observed and accounted for by the SELR that anaerobic digesters loaded at higher solids concentrations (resulting in greater inventory of microorganisms in the digesters) can be fed at higher loading rates. Insights into the economics of codigestion and allowable organic loading rates for high strength organic wastes help to overcome some of the barriers to widespread application of codigestion.

Analysis of the Environmental Benefits of Introducing Municipal Organic Waste Recovery in Hanoi City, Vietnam

Hanoi, the capital of Vietnam, is home to approximately 7 million people. In 2011, the city generated about 2,372,500 tons of municipal solid waste (MSW) (accounting for 11% of national generation) and the collection rate reached 85%, of which 84% was sent directly to landfills (without landfill gas capture systems). This conventional practice has caused not only adverse environmental impacts but also increased greenhouse gas (GHG) emissions and loss of recyclable resources. Since most of the waste generated in the city is organic waste (it accounts for 71% of municipal solid waste), there is high potential for organic waste recovery of MSW in Hanoi. This paper analyzes the potential for environmental benefits of introducing composting of municipal organic waste by proposing five alternative scenarios that range from current situation to composting of both commercial and household organic waste. In order to evaluate the environmental performance of the scenarios, we used three indicators: organic fertilizer production, landfill life extension, and GHG emission reduction. The results show that composting could produce a huge amount of organic fertilizer (i.e. from 6,424to 218,650 tons/year) depending on the scenarios. Diversion of organic waste to composting could reduce the amount of waste disposed in landfills resulting in extending landfill life significantly. Therefore, landfill lifecould be extended from 0.5 to 8.7 years compared to the current situation. Current MSW management practices contributed the highest amount of GHG emission accounting for 1,322,928 tonsCO2-eq/year, whereas the proposed scenarios decrease emissions in accordance with increasing the amount of organic waste used for composting. The estimated emission reduction from the proposed scenarios ranges from 15% to 98% compared to the current situation. The results suggest that composting could bring significant environmental benefits and is a key solution toward sustainable solid waste management for Hanoi city. In addition, composting highlights the potential of climate protection in the waste management sector.

Evaluation of organic waste diversion alternatives for greenhouse gas reduction

Greenhouse gas (GHG) emission analysis was performed for current and proposed organic waste management practices in the City of Madison, Wisconsin, United States of America (USA). Aiming for the long-term goal of zero waste, the City of Madison has been looking into an opportunity to divert its organic waste from its landfill. Previous studies suggested that organic waste diversion could result in a GHG emission reduction: Alternative treatment of organic waste would reduce GHG emissions through avoidance of landfill methane emission, nutrient replacement, and energy recovery when anaerobic digestion technologies are employed. However, organic waste diversion requires modification of collection practices and additions to the collection fleet. This would increase the GHG emissions and there is a need to balance emission reductions and the additional costs associated with a new organic waste diversion program. Collection practices are also important for the success of such a project, as it accounts for 83% of current operational cost for managing organic waste. The GHG emissions were quantified using the Life Cycle Assessment (LCA) approach. The current practice of composting of yard waste and direct disposal of other fractions of organic waste into the landfill were estimated to emit 224kgCO2-eq./ton of GHG. In contrast with the current practice, four alternatives were assessed in this study: windrow composting, high-solids anaerobic digestion, co-digestion at a large scale industrial waste anaerobic digester facility, and co-digestion at the local wastewater treatment plant. The results show that the co-digestion of source-separated organic waste would achieve the highest GHG emission reduction among the alternatives considered. The results were as follows: 81.5kgCO2-eq./ton for windrow composting; −46.0kgCO2-eq./ton for a high solids anaerobic digester; −156kgCO2-eq./ton for co-digestion with industrial waste; and −189kgCO2-eq./ton for co-digestion with sewage sludge. Co-digestion was favored as it shows the highest GHG emission reduction capacity while saving capital cost by almost half. However, the results of the GHG emission analysis were also affected by several factors external to the technologies chosen, including public participation, collection efficiency of organic waste, and types of waste collected. Based on the findings of this work, the party in charge of the organic waste diversion project should seek opportunities to partner with regional anaerobic digestion projects and local utilities, while continuing with its community outreach efforts.

Financial appraisal of wet mesophilic AD technology as a renewable energy and waste management technology

Anaerobic digestion (AD) has the potential to support diversion of organic waste from landfill and increase renewable energy production. However, diffusion of this technology has been uneven, with countries such as Germany and Sweden taking the lead, but limited diffusion in other countries such as the UK. In this context, this study explores the financial viability of AD in the UK to offer reasons why it has not been more widely used. This paper presents a model that calculates the Internal Rate of Return (IRR) on a twenty year investment in a 30,000 tonnes per annum wet mesophilic AD plant in the UK for the treatment of source separated organic waste, which is judged to be a suitable technology for the UK climate. The model evaluates the financial significance of the different alternative energy outputs from this AD plant and the resulting economic subsidies paid for renewable energy. Results show that renewable electricity and renewable heat sales supported by renewable electricity and renewable heat tariffs generates the greatest IRR (31.26%). All other uses of biogas generate an IRR in excess of 15%, and are judged to be a financially viable investment. Sensitivity analysis highlights the financial significance of: economic incentive payments and a waste management gate fee; and demonstrates that the fate of the digestate by-product is a source of financial uncertainty for AD investors.