Colocated firms can achieve environmental benefit and competitive advantage from exchanging physical resources (known as industrial symbiosis) with each other or with residential areas (referenced here as urban symbiosis). Past research illustrated that economic and environmental benefits appear selfevident, although detailed quantification has only been attempted of symbioses for energy and water utilities. This article provides a complimentary case study for Kawasaki, Japan. The 14 documented symbioses connect steel, cement, chemical, and paper firms and their spin-off recycling businesses.Seven key material exchanges divert annually at least 565 000 tons of waste from incineration or landfill. Four of these collectively present an estimated economic opportunity of 13.3 billion JPY (∼130 million USD) annually. Five symbioses involve utilization of byproduct and two sharing of utilities. The others are traditional or new recycling industries that do not specifically benefit from geographic proximity. The synergistic effect of urban and industrial symbiosis is unique. The legislative framework for a recycling-oriented society has contributed to realization of the symbioses, as has the availability of government subsidies through the Eco-Town program.

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Chinese government promotes ecological civilization in the-13 th five year planning‖ (2016-2020) period. As a result, ecological impacts become highlight in the national circular economy practices. To apply the eco-industrial development strategy to address the intertwined industrial and regional economic development, as well as related environmental and ecological challenges is key point. Urban industrial symbiosis provides a novel approach to realize the above expectation. Traditional evaluation on circular economy provided critical environmental insights, while to date, trade-offs of circular economy practices, and critical insights on regional eco-industrial development. It will shed a light on ecological civilization construction in China in the new national planning period.

We propose a new sequestration process for anthropogenic carbon dioxide (CO 2 ) that uses waste cement. The proposed process consists of two main reactions. The first is the extraction of calcium ions (Ca 2+ ) from waste cement particles by pressurized carbon dioxide (several megapascals of pressure). The second is the precipitation of calcium carbonate (CaCO 3 ). Ca 2+ extracted from waste cement is deposited as CaCO 3 when the pressure is reduced. CaCO 3 is disposed of directly, or recycled as a raw material for cement production. In the latter case, the same amount of CO 2 is considered to be sequestered because the net amount of virgin limestone mined can be reduced. The power consumption and cost of the proposed sequestration process for CO 2 emitted from a 100 MW thermal power plant were evaluated, on the basis of laboratory-scale experimental results. The power consumption for the operating process strongly depended on the operating conditions such as the cement/water ratio, the CO 2 pressure, and the average cement diameter. The minimum power consumption was 25.9 MW/100 MW of power generation when optimized within the operating conditions studied experimentally, and the sequestration cost associated with the power consumption (excluding capital and maintenance) would be about $22.6/t of carbon dioxide. This result indicates that the present process is highly competitive with previously reported CO 2 sequestration scenarios such as ocean sequestration. Sensitivity analysis of the operating parameters was carried out on the operating power consumption, and it was found that a smaller ratio of waste cement to water and a lower CO 2 pressure will decrease the operating power consumption.

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