According to the Knowledge Product (KP) studies commissioned by the Department of Environmental Affairs (DEA), in-vessel composting (IVC) is a method of accelerating the composting process within an enclosed environment. Waste is screened and any oversize items removed. The waste is then shredded or chipped to increase the surface area and reduce the average material size. Source segregation of organic wastes often requires a limited amount of treatment before composting. The composting process takes place under controlled moisture content, temperature, oxygen, and carbon to nitrogen ratios (C:N) in an enclosed environment, either within buildings (bays, beds) or in composting vessels (tunnels, drums, towers). To keep a composting process sufficiently aerobic, oxygen concentrations of at least 5% within the compost pile are typically recommended. Since highly active aerobic micro-organisms use oxygen rapidly, maintaining aerobic conditions throughout a compost pile — particularly at the core — requires constant monitoring, plus fan-powered aeration or frequent mechanical turning.
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Read more (http://www.earthprobiotic.com ) EMPERORS PALACE FOOD WASTE COMPOSTING SUMMARY: During the period September 2015 to July 2016, Emperors Palace has been composting its food waste using Earth Probiotic’s in-vessel composting machine; the Heron IVC. To date Emperors Palace has diverted over 57,791 kg of food waste from landfill. The Heron IVC is positioned as an alternative waste management solution to landfilling, with compost as a beneficial by-product of this alternative system. TECHNOLOGY The Heron IVC is a flow-through enclosed composting unit using mechanical aeration to enable composting of the full food waste matrix. The composting machine uses a five-stage process to ensure an optimum composting process:
Other than manual loading and removal of the discharged compost, the system is completely automated by Earth Probiotic’s programme logic controller (PLC). In addition to the mixing and aeration of the matrix, the composting is processed by the addition of composting microbes specifically developed for Earth Probiotic by the Council for Scientific and Industrial Research (CSIR). MONITORING METHODOLOGY AND PROCESS
FOOD WASTE DIVERSION RESULTS AND CO2 IMPACT Emperors Palace’s key metrics for the evaluation of this technology are specific to the volume of waste diverted from landfill and the consequent saving of CO2e emissions which can be directly attributed to the programme.
Chart 1: Waste Diversion and CO2e impact
CO2e measurement is based on the UK Department for Environment, Food and Rural Affairs (DEFRA) calculations of 235kg/t(FW) savings through composting vs. landfill emissions measured at 335kg/t(FW). As the composting process does generate CO2 emissions at 100kg/tonne the savings vs. landfill are set at 235kg/t(FW). In addition to CO2e emissions savings, a significant environmental benefit of this diversion process is landfill airspace savings. In Gauteng, many landfills are nearing end of life and face closure. Future landfills will be built further away from communities and thus lead to higher waste disposal costs (and a larger carbon footprint). There is thus an economic and environmental imperative to reduce landfill loads as much as possible. Since installation of the Heron IVC, Emperor’s Palace have saved 87m3 of landfill airspace.
Chart 2: Landfill Airspace Saving
For this analysis, Earth Probiotic has used Pikitup’s estimate of 1,000kg of food waste taking up 1.5m3 of landfill airspace. CONCLUSION The key aspect of improving through-put of volumes through the Heron IVC is separation at source. Separation at source solves a number of key issues in the waste arena:
While the Emperors Palace case demonstrates the viability of the Heron IVC, optimising processes and programming of the machine is an ongoing project. For instance, food seasonality leads to changes in the recipe with more bulking carbon agents required due to moisture loads from citrus and soup. Source: tel +27 (0)11 959 1085 • fax +27 (0)86 275 2478 www.earthprobiotic.com P.O.Box 37 Morningside 2057 Gauteng South Africa Earth Probiotic Recycling Solutions (Pty) Ltd : Company Registration 2010/018897/07
Read more (http://www.closingtheloop.co.za ) Case Study: Waste to Food (PTY) LTD In Vessel Composting and Vermiculture Application Conversion of nutrient-rich organic wastes into high quality agricultural inputs. Problems solved
Technologies utilised In-vessel composting followed by earthworm composting (vermicomposting). Research has shown that in-vessel composting and vermicomposting are complimentary. In vessel composting followed by vermicomposting is more efficient – and linking these technologies leads to a higher quality end-product. HotRot is a leading in-vessel composting system developed in New Zealand. The Worm Hammock is a South African developed industrial-scale vermicomposting system suited to local and developing world applications.
The HotRot continuous flow in-vessel composting system agitates and aerates putrescent wastes, mixing them together with a carbon-rich bulking agent (chipped garden or timber waste). This leads to rapid decomposition and stabilisation of the organic waste.
The Worm Hammock continuous flow vermicomposting system provides conditions that are conducive to further stabilisation of the organics and the promotion of beneficial characteristics and high quality organic compost products. The raised, multi-stage layers in the system promote efficient materials handling and efficient processing.
Feed hopper and HotRot 1811.
Project and process description
Waste to Food is located adjacent to the Philippi Fresh Produce Market in Cape Town. The company has been using 10 Worm Hammock units to process fruit and vegetable waste from local Fresh Produce Markets. Waste to Food recently secured a R9 million investment to expand its process to include in-vessel composting and small-scale anaerobic digestion. This investment will also provide equipment, infrastructure and manpower required to produce a range of high-quality products for the agriculture, horticulture and floriculture markets. Waste to food processes food and other organic wastes together with chipped garden waste. Heat generated by the in-vessel composting process kills pathogens and weed seeds and preconditions the composting material to make it palatable to earthworms. The pre-composted organic material is then vermi-composted in Worm Hammocks to further stabilise the organic material and promote beneficial qualities. Nutrient rich liquid and high-quality earthworm compost are used on site to grow food crops and ornamental plants.
Waste to Food process flow (above) shows the integration of in-vessel composting technology with anaerobic digestion and vermicomposting. The processes are linked to generate high quality organic products and avoid the production of waste products. The HotRot 3518 unit is able to process over 10 tons of organic waste each day (Grabouw Waste Water Treatment Facility, Elgin, Western Cape). Worm Hammocks at Waste to Food’s Philippi East site (at the Philippi Fresh Produce Market). The HotRot in-vessel composting system is modular and multiple units can be used for large-scale applications. The concrete hull elements of the HotRot 3518 are cast locally and local content can be increased in future builds. Individual Worm Hammock units are connected in rows and can be scaled to the project’s requirements.
Source: Closing the Loop
According to the Knowledge Product (KP) studies commissioned by the Department of Environmental Affa...
According to the Knowledge Product (KP)studies commissioned by the Department of Environmental Affai...