Microbial-Based Treatment of Kitchen Waste and Kitchen Wastewater: State-of-the-Art Progress and Emerging Research Prospects Related to Microalgae and Bacteria

Purpose of ReviewThis review intends to recapitulate the pretreatment measures of kitchen waste and kitchen wastewater (KWAKWW). Furthermore, this review also separately summarizes the ascendancy of using bacteria, microalgae and microalgae-bacteria consortia to treat KWAKWW, and corresponding emerging reinforcement strategies.Recent FindingsTremendous amount of KWAKWW are annually generated in the whole world. Wherein roughly 1.3 billion tons of kitchen waste (KW) are dumped and which were forecasted that would increase to about 2.5 billion tons by 2025. In addition, KWAKWW have the characteristics of high content of refractory organic matter (e.g., oil and cellulose), water (commonly outstrip 70%), and salt, which is difficult for bacteria or microalgae to treat. Consequently, it is essential to perform efficacious pretreatment measures to boost the efficiency of post-treatment. Utilizing bacteria, microalgae, and microalgae-bacteria consortia to treat KWAKWW is considered an efficient strategy due to ascendancy of puissant deep purification ability, excellent resource appreciation effect, and low operation costs. For instance, bacteria could produce leastways four kinds of products through KWAKWW; multiple studies indicated that microalgae generally could remove exceed 70% of nutrients of KWAKWW; one research manifested that microalgae-bacteria consortia retrenched 46% of the demand about dissolved oxygen (DO). Nevertheless, the above microbial treatment systems still have some inherent drawbacks such as poor impact resistance. Fortunately, metabolic engineering and other strengthen strategies can efficaciously upgrade the nutrient removal and resource utilization performance of bacteria, microalgae, and microalgae-bacteria consortia. For example, one research shown that the 1-butanol productivity of original bacteria remarkably increased by 93.48-171.74% draw support from metabolic engineering.SummaryA total of 221 papers related to the content of this review were searched through Web of Science (http://apps.webofknowledge.com). What is more, specific data that emerged on this review were all extracted from the above-searched papers. The mechanisms and effect of hydrothermal carbonization (HTC) and other four pretreatment measures are introduced by this review in detail. The preponderance of utilizing bacteria, microalgae, and microalgae-bacteria consortia to treat KWAKWW are comprehensively evaluated mainly from the perspectives of nutrient purification and resource utilization. Four state-of-the-art strengthen strategies like machine learning are then introduced. Finally, the current challenges in KWAKWW treatment are summarized from five aspects, and future concrete improvement directions are also provided. Overall, this review outlines the state-of-the-art research progress of KWAKWW treatment by bacteria and microalgae and tenders corresponding implementation schemes for improving KWAKWW treatment effect.