A review on generation, composition, and valorization of dairy processing sludge: A circular economy-based sustainable approach

초록

This dairy industry has grown considerably in the last decade to meet the increasing requirements of the everrisinghuman population. Large volumes of solid waste are generated during the processing of dairy wastewater,known as dairy processing sludge (DPS). Organic and inorganic chemicals, carbon, nitrogen, phosphorus,chlorides, sulfides, fats, oils, and grease comprise most of the DPS. Discharging untreated DPS into surroundingwater sources harms the environment because of its elevated organic contents. Alternatively, the DPS canpotentially be transformed into struvite, char, and ash with some fertilizer equivalence values. DPS containsheavy metals, pathogens, and synthetic organic compounds (hormones and pesticides) and requires pretreatmentbefore its direct application as a fertilizer equivalent. DPS can be effectively treated by non-conventionalmethods, such as earthworms converting it into nutrient-rich fertilizer. Moreover, circular economy principlescan be fulfilled by recycling DPS into value-added products, such as bacterial growth media for rhizobia, stabilizingcontaminated soil for growing biofuel plants (e.g., Jatropha), and further used as a potential substrate forbiodiesel production. This review elucidates the generation, composition, treatments, and opportunities forreusing DPS in a sustainable and eco-friendly manner that minimizes environmental pollution and identifiesimportant future research prospects.

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