Evaluation of the Potential to Produce Biogas and Other Energetic Coproducts Using Anaerobic Digestion of Wastewater Generated at Shrimp Processing Operations

Abstract

Shrimp processors in the United States each year operate via a staggered schedule of harvest runs that usually encompass about two to four months per run staggered between two to three month intervals. They typically use aerobic biotreatment for their wastewater management which yields no coproducts. This study considered a scenario where intermittent use of an anaerobic digester to produce methane (via biogas) during treatment of the wastewater was evaluated as if the digester was restarted multiple times per year. The overall study goal was to determine if an anaerobic digester could meet treatment goals (set at 60% removal of the chemical oxygen demand or COD) while producing a biogas containing >60% CH4 (v/v). The results indicated that nitrogen amending coupled with adding a microbial seed collected at the digester from a local municipal wastewater treatment plant provides good performance in terms of both biogas production and COD removal. Digestion of the shrimp processing wastewater yielded high levels of methane in the biogas at over 70% (v/v). About 3.5 ft3 CH4 per pound of input COD was produced in the nutrient amended and seeded digester system. Anaerobic digestion can produce other valuable products other than biogas such as volatile organic acids (VOAs), including acetic, proprionic, and lactic acids. Approximately 2 g/L of VOAs could be produced via a 10 day hydraulic residence time using a similar system that was pretreated via conditions reported by others to enhance the production of VOAs, but the level of VOA production obtained was not considered economically attractive. An assessment of the economics of a centralized digestion system that could service multiple processors indicated that the centralized unit would produce a slightly higher return on investment than that typically observed with digestion systems at animal raising and food processing facilities.

Microbial Lipid Production through Integrated Anaerobic-Aerobic Biotreatment Process: An Urban-Based Biorefinery Concept

“…The sludges were inoculated or used in the batch experiments within an hour after collection. Prior to inoculation, the anaerobic sludge was concentrated 2.5X by centrifugation to remove excessive water and inoculated at a fixed loading equivalent to 5% (v/v) based on the original volume of anaerobic sludge. , Similarly, the activated sludge was concentrated by centrifugation and was seeded at a solids concentration of ∼10 g/L following the procedure by Fortela et al…”

“…The composition of gaseous samples from the anaerobic fermentation was determined by gas chromatography, while liquid samples were subjected to liquid chromatography to analyze for residual glucose and SCCAs based on the authors’ previous works. , Collected liquid samples from the lipid accumulation runs were analyzed for biomass and lipid content. Biomass concentrations were measured gravimetrically by centrifugation followed by drying.…”

“…Prior to inoculation, the anaerobic sludge was concentrated 2.5X by centrifugation to remove excessive water and inoculated at a fixed loading equivalent to 5% (v/v) based on the original volume of anaerobic sludge. 30,31 Similarly, the activated sludge was concentrated by centrifugation and was seeded at a solids concentration of ∼10 g/L following the procedure by Fortela et al 21 Batch Experiments. For this study, a medium formulation (Test Medium) (see Table 1) was evaluated for both anaerobic and aerobic cultivations.…”

Unraveling the Carrier Dynamics and Photocatalytic Pathway in Carbon Dots and Pollutants of Wastewater System

“…7−13 Among all developed technologies related to the research of wastewater treatment, photocatalysis is used more due to the utilization of solar energy to produce renewable H 2 from the wastewater. 14,15 In that scenario, robust, nontoxic, low-cost, and watersoluble photocatalysts are required to work with excellent performances in untreated water resources. Most photo-sensitizers such as TiO 2 , ZnO, quantum dots, organic dyes, and carbon nitride used for that purpose are toxic, are insoluble in water, have weak interfacial interactions, and have slow electron transfer kinetics.…”

“…Wastewater contains numerous pollutants such as metal ions and organic and inorganic elements; among them organic and inorganic pollutants are the main pollutants that industrial water yields. We focus on two important wastewater organic pollutants, pyrazine (PYZ) and benzoquinone (BQ), due to the matching of their redox energy level with the photosensitizer carbon dots (C-Dots). − To date various technologies have been developed and commercialized to purify and separate pollutants from wastewater, such as ion exchange, anaerobic technologies, biofilm technologies, membrane separation, adsorption process, chemical processes, and photocatalysis. − Among all developed technologies related to the research of wastewater treatment, photocatalysis is used more due to the utilization of solar energy to produce renewable H 2 from the wastewater. , …”