Carbon Dioxide Recovery from Composting

堆肥是一种既定的废物管理选择，它将城市垃圾填埋场中的有机废物转移，使其稳定下来，并将残渣回收用于农业。通常，堆肥是一种户外过程，将有机材料储存在可定期翻转的窗帘(长堆)中，以增强生物活性。通过确保微生物有足够的氧气，即将材料从堆边移动到表面，从而增强生物活性。生物活性将部分有机物转化为二氧化碳和水，从而释放热量。这些气体和热量通过正常的燃烧被排放到大气中，产生的二氧化碳浓度按体积计算约为6%。二氧化碳是一种宝贵的工业气体，不久将通过尚未公布的国家碳计划得到重视。即将到来的碳价格将增加工业二氧化碳消费者的成本，工业二氧化碳通常来自炼油厂或其他基于化石燃料的浓缩来源。我们将调查一个封闭系统，该系统允许捕获堆肥过程产生的二氧化碳，同时潜在地增加生物活性比率。该项目的主要重点将是增加堆肥废气中的二氧化碳浓度，捕获废气以促进分离过程，并增加细菌的氧气利用率。这将通过测试堆肥过程的几个重新设计来实现，包括增加空气流量、将废气与新鲜空气混合(提高二氧化碳水平)、使用产生的氧气(例如，从空气分离中产生的纯氧气或混合氧气)以及将堆肥移动到移动的炉排系统上。这些方法的性能改进将在可能的情况下转化为每吨捕获二氧化碳的成本。

Composting is an established waste management option that diverts organic waste from city landfills, stabilizesit and recycles the residue for agriculture. Typically, composting is an outdoor process where the organicmaterial is stockpiled in windrows (long piles) that can be turned periodically to enhance biological activity.The biological activity is enhanced by ensuring adequate oxygen for the microbes, that is moving material frominside the pile to the surface. The biological activity converts a portion of the organic matter to carbon dioxideand water thus releasing heat. These gases, and heat, are vented to the atmosphere with normal compostingproducing carbon dioxide concentrations of about 6% by volume. Carbon dioxide is a valuable industrial gasand will soon be valued through the national carbon plan yet to be unveiled. The coming price on carbon therewill be added costs to consumers of industrial CO2, which is normally sourced from refineries or otherconcentrated, fossil fuel based, sources.We will be investigating a closed system that allows for capturing of the CO2 produced by the compostingprocess while potentially increasing the biological activity rate. The main focus of the project will be toincrease the CO2 concentration in the compost exhaust, capture the exhaust to facilitate the separation processand increase the oxygen availability to the bacteria. This will be accomplished by testing several redesigns ofthe composting process including increasing the air flow, blending exhaust air with fresh air (raising CO2levels), using produced oxygen (e.g. from air separation either pure or blended) and moving the compost on amoving grate system. The performance improvement of these methods will be converted into a cost per tonneof CO2 captured where possible.