Composting processes for food processing wastes: A review

Composting of food processing waste was analyzed as a biological process and an engineered system. The goal is to establish fundamental principles and design criteria that would aid its adoption as waste management practice. Characteristics of the inflow, reactor, and outflow were evaluated. Success of the bioreactor was found to be largely dependent on microbial community structure, physical properties of biodegradable waste (BW), aeration, heat transfer, and time required for maturation. Static piles were the primary focus of this article for cost and energy efficiency.

Continuous Thermal Stripping Process for Ammonium Removal from Digestate and Centrate

The state of California has passed legislation to divert organic materials from landfills to reduce the emission of methane to the atmosphere. A large amount of this source separated organic (SSO) material is expected to be used as a feedstock for anaerobic digestion processes. Based on a review of properties for likely SSO feedstocks, it is clear that while SSO are high in volatile solids, they are also concentrated sources of nutrients (principally, ammonium). When SSO feedstocks are digested, these nutrients are released into the digestate, where ammonium can cause problems both within the digester and in downstream treatment processes. The focus of this paper is on the performance of two pilot studies designed to remove ammonia from a digester effluent. The process used in the study is a thermal stripping column with tray configuration, operating under a vacuum. In the first study, food waste digestate was treated as a slurry in the stripping column with and without NaOH addition. At process temperatures near 90 °C, the performance with and without caustic was similar. In the second study, centrate from a co-digestion facility, that blends food processing waste with wastewater process solids, was treated in the same thermal stripping column under the same conditions and without chemical addition. The results from both studies, which can be described using the same performance curves, are presented and discussed in this paper.

Industrially Important Enzymes Production From Food Waste

To link food demand and reduction in food waste, proactive approaches should be taken. Perishable food is mainly fruits and vegetables, waste from different processing industries like pulses, meat products, oil products, dairy products, and fishery byproducts. Conventional food waste management solution is land filling which is not sustainable as it generates global warming gases like methane and carbon dioxide. To reduce food waste, the process known as “food valorization” has become another solution to landfilling, the concept which is given by European Commission in 2012, meaning food processing waste conversion to value-added products. In this chapter the study focuses on production of industrially important enzymes from food waste which could be one of the reactive solutions. Different enzymes like pectinase, peroxidase, lipase, glucoamylase, and protease can be produced from food waste.

Green Routes for the Development of Chitin/Chitosan Sustainable Hydrogels

The eco-sustainable use of materials derived from agricultural and food processing waste will represent one of the most stimulating challenges shortly. Chitin and chitosan are two remarkable examples of how molecules with high added value can be extracted from food waste, such as crustaceans’ shells, fungi, mollusks, etc. This Perspective summarizes the current state of knowledge about chitin extraction, chitosan production, and hydrogel formation, highlighting the environmental critical steps in the common route (use of strong acids and basis, toxic solvents, and not eco-friendly crosslinkers). At the same time, promising green alternatives are described and analyzed. Examples are the employment of NADESs or DESs (such as choline chloride: urea or choline chloride: organic acids mixtures) for chitin extraction and dissolution, use of citric acid both in chitin extraction and hydrogel formation or utilization of natural extracts, like genipin, as green cross-linkers under mild conditions (heating at 37 °C for 12 h). In particular, this perspective aims to provide a stimulating basis for the development of processes based on the recycling and reusing of chemicals, during the different preparation steps, in line with “system chemistry” and “circular economy” principles.

Mixed greywater treatment for irrigation uses

Water contamination comes from many different sources, including, among others, factories, sewage treatment plants, mining activities (heavy metals), food-processing waste, agriculture runoff, animal waste, disposal of personal care products, and household chemicals. Therefore, the reuse of wastewater has become a fundamental strategy for sustainable water management and maintaining environmental quality. In this sense, this research presents a simple and economic alternative to solving the problems caused by greywater, resulting from laundry activities. This paper evaluates a mixed system for the treatment of greywater. The mixed system has physical filters that are composed of river stone, concrete, river sand, and coal. A bioremediation technique is also evaluated, involving two types of aquatic plants, watercress (Nasturtium officinale L.) and duckweed (Lemma minor L.). This study showed significant differences in pH reduction, from 9.56 to 7.50, total suspended solids (TSS), from 1742.00 mg/L to 298.50 mg/L, phosphates, from 1.12 mg/L PO43¯ to 0.31 mg/L PO43- , and chemical oxygen demand (COD), from 472.38 mg/L to 8.52 mg/L. Thus, the results indicate that this system is efficient for the reuse of grey water for irrigation uses. Moreover, each parameter, with the exception of dissolved oxygen and total suspended solids (TSS), meets the maximum limits set by the Environmental Quality Standards for Category 3: irrigation water for vegetables and animal beverages and the FAO irrigation water standards.