G. Larry Newton

A value added manure management system using the black soldier fly

Abstract A manure management system for laying hens using the black soldier fly, Hermetia illucens (L.) converted manure to a 42% protein, 35% fat feedstuff, reduced manure accumulation by at least 50% and eliminated house fly breeding. No extra facility or added energy was required. Mature larvae self-harvested producing a feedstuff as they attempted to pupate. Optimal feedstuff to manure dry matter yield was 7·8%. This insect occurs worldwide in tropical and warm-temperature regions and can digest many biological wastes.

The use of fly larvae for organic waste treatment

The idea of using fly larvae for processing of organic waste was proposed almost 100 years ago. Since then, numerous laboratory studies have shown that several fly species are well suited for biodegradation of organic waste, with the house fly (Musca domestica L.) and the black soldier fly (Hermetia illucens L.) being the most extensively studied insects for this purpose. House fly larvae develop well in manure of animals fed a mixed diet, while black soldier fly larvae accept a greater variety of decaying organic matter. Blow fly and flesh fly maggots are better suited for biodegradation of meat processing waste. The larvae of these insects have been successfully used to reduce mass of animal manure, fecal sludge, municipal waste, food scrapes, restaurant and market waste, as well as plant residues left after oil extraction. Higher yields of larvae are produced on nutrient-rich wastes (meat processing waste, food waste) than on manure or plant residues. Larvae may be used as animal feed or for production of secondary products (biodiesel, biologically active substances). Waste residue becomes valuable fertilizer. During biodegradation the temperature of the substrate rises, pH changes from neutral to alkaline, ammonia release increases, and moisture decreases. Microbial load of some pathogens can be substantially reduced. Both larvae and digested residue may require further treatment to eliminate pathogens. Facilities utilizing natural fly populations, as well as pilot and full-scale plants with laboratory-reared fly populations have been shown to be effective and economically feasible. The major obstacles associated with the production of fly larvae from organic waste on an industrial scale seem to be technological aspects of scaling-up the production capacity, insufficient knowledge of fly biology necessary to produce large amounts of eggs, and current legislation. Technological innovations could greatly improve performance of the biodegradation facilities and decrease production costs.

Survival dynamics of fecal bacteria in ponds in agricultural watersheds of the Piedmont and Coastal Plain of Georgia.

Animal agriculture in watersheds produces manure bacteria that may contaminate surface waters and put public health at risk. We measured fecal indicator bacteria (commensal Escherichia coli and fecal enterococci) and manure pathogens (Salmonella and E. coli 0157:H7), and physical-chemical parameters in pond inflow, within pond, pond outflow, and pond sediments in three ponds in agricultural watersheds. Bishop Pond with perennial inflow and outflow is located in the Piedmont, and Ponds A and C with ephemeral inflow and outflow in the Coastal Plain of Georgia. Bromide and chloride tracer experiments at Bishop Pond reflected a residence time much greater than that estimated by two models, and indicated that complete mixing within Bishop Pond was never obtained. The long residence time meant that fecal bacteria were exposed to solar UV-radiation and microbial predation. At Bishop Pond outflow concentrations of fecal indicator bacteria were significantly less than inflow concentrations; such was not observed at Ponds A and C. Both Salmonella and E. coli 0157:H7 were measured when concomitant concentrations of commensal E. coli were below the criterion for surface water impairment indicating problems with the effectiveness of indicator organisms. Bishop Pond improved down stream water quality; whereas, Ponds A and C with ephemeral inflow and outflow and possibly greater nutrient concentrations within the two ponds appeared to be less effective in improving down stream water quality.

Winter Feeding Frequency for Channel Catfish in Cages

Abstract Cage-stocked channel catfish (Ictalurus punctatus) with an average initial weight of 99 g were fed once a day on alternate days or once weekly throughout the winter (19 November–22 April). Total fish weight per cage on the alternate-day schedule increased by 32.1% over the study period. Less weight gain per cage was produced when fish were fed once weekly (1.7–8.5% weight gain; P < 0.01). Channel catfish weight can be maintained by once-weekly feedings during warm winters (mean water temperature near 16.3°C) by feeding during warming trends.

MANURE MANAGEMENT STRATEGIES AND TECHNOLOGIES

A number of manure management strategies are used for both open lot and confinement facilities in the U.S. The primary control strategies for open lots are solids removal using settling basins and containment followed by land application of the liquids. These management strategies are dictated by federal law for large open lots. Smaller lots may or may not capture and land apply the runoff liquid. Both large and small lot operators must haul and distribute manure solids on the land. Solid manure spreaders that apply uniform rates is a major research need. Confinement facilities rely primarily, but not exclusively, on liquid handling systems. Two general categories of liquid systems are pits, or slurry systems, and lagoons, primarily anaerobic lagoons. Anaerobic lagoon design has been researched and is well known to environmental engineers. Anaerobic lagoons work better in warm climates where biological activity continues most of the year. Anaerobic digesters with controlled temperatures can be used to produce biogas and reduce pathogens, but are difficult to justify due to high capital costs, high management requirements and a lack of incentives for using the systems. Covered lagoons and anaerobic digesters can significantly reduce odors and releases of unwanted gases. Naturally aerobic lagoons can reduce nitrogen in the liquid significantly, but are impractical because of large size requirements. Mechanically aerated lagoons are sometimes used. Autothermal thermophilic aerobic digestion, biofilm reactors, sequencing batch reactors, and combinations of anoxic and aerobic treatments are being researched, and offer advantages of odor reduction, and waste degradation and stabilization. Additional research is needed to optimize these systems for nutrient reduction, pathogen destruction, and energy use. Solid-liquid separation can be used for both open lots and confinements. Open lots typically use settling basins. Confinements typically use mechanical separators. The efficiency of a separator depends on the type of waste and the separator. It’s difficult to achieve high efficiencies of separation without pretreatment with coagulating chemicals. Solids from both separators and from open lots are sometimes composted. Wetland treatment of manure liquids has received some research attention. It has been shown to offer some nutrient reduction advantages when designed properly. Initial design parameters have been determined for animal waste systems, but continued research is needed to adapt wetland systems to different types of livestock operations. Chemical amendments remain a question. Both feed additives and manure additives have been tested by a number of researchers, and have achieved only moderate success at best. Much research is needed before chemical additives will be major contributors to manure control solutions. Land application systems are well developed, but always need continued work to improve efficiencies and effectiveness. One of the primary areas of research needs currently is for injection units that minimize disturbance of the soil and crop residue cover. Insect digestion of manure solids has been well researched in laboratory settings. Effective field production systems need to be devised, and uses for the resultant high protein feedstuffs need to be developed. Many of the above technologies can be combined into integrated treatment systems that protect soil, air, and water quality. Manure management strategies are different for manure from a confinement system (used here to mean a totally roofed facility) and from an open lot, or partial open lot system. Because open lots are subject to hydrologic phenomenon such as rainfall, runoff, sunlight, and evaporation, they are very different from confinement systems. Although there are some similarities, there are many differences.

Treatment of Aquaculture Wastewater Using Floating Vegetated Mats

Methods are needed for treating aquaculture wastewater. The goal is to improve water quality sufficiently for it to be recycled to production ponds. One method is to use floating vegetation in treatment tanks. Alternatively, the floating vegetation could be grown directly on the production ponds. A study with floating vegetated mats for improving aquaculture wastewater quality is being conducted at the Univ. of GA Aquaculture Unit in Tifton, GA. The objective is to determine amount of biomass produced, nutrients removed, and quality of the treated wastewater. Wastewater from fish-production ponds is pumped into sets of 1285 L aquaculture tanks. There are three tanks in series in each treatment set, and three replicate sets per vegetative species. Each tank contains a floating platform (1 m2) for growth of vegetation. During a prototype test of wetland, horticultural, and agronomic plants, it was determined that cattail, iris, or soft rush were suitable for growing in aquaculture wastewater. The treatments are three-tank sets of cattail, iris, soft rush, or a control (no plants). The water is circulated every three weeks such that tank 1 receives water from the fish pond, tank 2 receives water from tank 1, tank 3 receives water from tank 2, and tank 3 is drained into a nearby storage pond. Water samples for analyses are collected from each tank prior to transfer to the next tank. Plant biomass is harvested as needed. Measurements are made of total biomass per tank and nutrient content (N, P, and K) of the plant tissue. Water quality measurements include N, P, K, BOD, chlorophyll, O2, turbidity, and pH. This paper presents partial results of the three-year study which started in May 2009.