A critical analysis of the novel sewage treatment concept of anaerobic digestion followed by CO₂ capture by microalgae has been carried out, with particular reference to India. The anaerobic process would convert the sewage COD into methane and CO₂, the latter being converted into microalgae in a photobioreactor process, using sunlight as an energy source. The microalgae can be used to produce biofuels, co-fired with high yielding fuels (like coke) or just recycled back into the anaerobic digestion cycle as a substrate for methane production. Overall, this process would allow, at least in principle, the conversion of all the carbon in the municipal wastewaters into fuels. This study reports data on municipal wastewater generation and treatment facilities across the globe. The focus is then given to sewage generation and treatment in Indian cities, classified into metropolitan, Class-I and Class-II cities. Aerobic and anaerobic digestion processes for sewage treatment are then compared with a discussion on the advantages of the anaerobic membrane bioreactor (AnMBR). The advantages and limitations of photobioreactors for microalgae growth are discussed. Mass balances are then carried out with reference to sewage flows and concentrations in India, and the potential energy generation from the process is estimated. Overall, the complete process is envisaged to produce about 1.69 × 10⁸ kWhd⁻¹ of energy from biogas and microalgae. This has the potential to replace 3% of the recent total petroleum product consumption in India. The study goes towards “zero discharge” of waste to the environment, thus representing a promising sustainable development.

对厌氧消化后再通过微藻捕获CO ₂的新型污水处理概念进行了严格的分析，特别是在印度。厌氧过程会将污水中的COD转化为甲烷和CO ₂，利用阳光作为能源，通过光生物反应器将后者转化为微藻。微藻可用于生产生物燃料，可与高产率燃料（如焦炭）共烧，或仅作为甲烷生产的底物循环回厌氧消化循环。总的来说，该过程至少在原则上将允许将城市废水中的所有碳转化为燃料。这项研究报告了全球范围内市政废水产生和处理设施的数据。然后将重点放在印度城市的污水产生和处理上，这些城市分为大城市，I类和II类城市。然后将用于污水处理的好氧和厌氧消化工艺与关于厌氧膜生物反应器（AnMBR）优点的讨论进行了比较。讨论了光生物反应器在微藻生长中的优势和局限性。然后参照印度的污水流量和浓度进行质量平衡，并估算该过程产生的潜在能量。总体而言，整个过程预计将产生约1.69×10来自沼气和微藻类的能量为⁸ kWhd ^-1。这有可能取代印度最近的石油产品总消费量的3％。该研究致力于将废物“零排放”到环境中，从而代表了有希望的可持续发展。