Don Augenstein

Fuel gas recovery from controlled landfilling of municipal wastes

Abstract Experiments were carried out in unstirred reactors for the digestion to fuel gas of shredded municipal solid waste and sewage sludge at high total solids concentration. Waste and sludge solids together comprised up to 48 percent by weight of the reactor contents. Finely divided calcium carbonate dispersed in the aqueous phase was employed as a pH buffer. Results of experiments showed that conversion to fuel gas of up to 0.128 m3/ kg (2.04 ft3 CH4 (STP)/lb) solid waste was obtained. In a separate experiment, alkaline pretreatment of the solid waste component preceding digestion further improved conversion to fuel gas. An engineering analysis was conducted for application of these results to a controlled landfill system. For an approximately 1.04 Gg/day (1150 U.S. tons/day) at 7 day/week municipal waste system, based on documented equipment costs and an accepted private utility financing method, the incremental capital cost to modify a landfill for fuel gas production was estimated to be

Design of capsules that burst at predetermined times by dialysis

4.6 million, and incremental operating cost under

Quantifying Factors Limiting Aerobic Degradation During Aerobic Bioreactor Landfilling

300,000 per year. Heating value of the fuel gas generated was estimated to be 1.33 × 106 GJ/year (1.26 trillion BTU/year) and the fuel gas cost was estimated to be near

An evaluation of the bioconversion of woody biomass to calcium acetate deicing salt

0.70/GJ (

Performance evaluation of an anaerobic/aerobic landfill-based digester using yard waste for energy and compost production.

0.74/million BTU). It appears that the system evaluated has potential for making possible the economic recovery of fuel gas from solid waste (or other solid substrates) through substantial reduction in the capital and operating costs of a conventional anaerobic digestion system.

Mitigating methane emissions and air intrusion in heterogeneous landfills with a high permeability layer

Abstract This paper presents a mathematical model of a capsule or coating that ruptures after a predetermined time on exposure to water. A biodegradable capsule of this sort could be used to deliver pulsed doses of drugs (e.g. hormones) to patients, to release insecticides a certain time after a rainfall, etc. The model of a spherical capsule suggests that the time it takes to burst can be controlled successfully by the initial radius and wall thickness, provided a design criterion is met. If N 2 = P 0 r 0 /2 Ml 0 ( P 0 is the osmotic pressure of the contents, r 0 is the initial radius, M is the modulus of elasticity, and l 0 is the initial thickness of the capsule wall) is larger than two times N 1 = Y/M ( Y is the yield stress), the capsules bursting time will be approximately a linear function of the initial radius and a quadratic function of wall thickness. If N 2 N 1 , the bursting time is either radically sensitive to initial radius and wall thickness, or else the capsule does not burst.

Composting of municipal solid waste and sewage sludge: Potential for fuel gas production in a developing country

A bioreactor landfill cell at Yolo County, California was operated aerobically for six months to quantify the extent of aerobic degradation and mechanisms limiting aerobic activity during air injection and liquid addition. The portion of the solid waste degraded anaerobically was estimated and tracked through time. From an analysis of in situ aerobic respiration and gas tracer data, it was found that a large fraction of the gas-filled pore space was in immobile zones where it was difficult to maintain aerobic conditions, even at relatively moderate landfill cell-average moisture contents of 33-36%. Even with the intentional injection of air, anaerobic activity was never less than 13%, and sometimes exceeded 65%. Analyses of gas tracer and respiration data were used to quantify rates of respiration and rates of mass transfer to immobile gas zones. The similarity of these rates indicated that waste degradation was influenced significantly by rates of oxygen transfer to immobile gas zones, which comprised 32-92% of the gas-filled pore space. Gas tracer tests might be useful for estimating the size of the mobile/immobile gas zones, rates of mass transfer between these regions, and the difficulty of degrading waste aerobically in particular waste bodies.

Multi-stage digestion of municipal solid waste to fuel gas

Abstract A competitive process is described using local woody biomass residues, which may also include associated pulp and paper wastes, or municipal solid waste, as potential feedstocks for bioconversion to calcium acetate, an alternative deicing salt. The process first involves “suppressed methane” fermentation of these woody biomass residues in a “packed bed” fermentor for the production of acetic acid. In earlier experimental work, operation of conventional anaerobic digestion systems in this suppressed methane mode has yielded a product of over 85% acetic acid, the remainder primarily being other organic acids such as propionic and butyric acids; operation at thermophilic conditions (60°C) yielded essentially all acetic acid. In the process described, recovery of the dilute organic acids (=3.5% acetic acid) will be by liquid ion exchange extraction. Product calcium acetate is formed by back extraction of liquid ion exchange with calcium hydroxide. After spray drying, this calcium acetate is ready for use as an organic deicing salt. Pretreatment of woody biomass may be by “steam explosion” or by mild alkali treatment to breakdown the lignin fraction for fermentation to acetic acid; however, if cellulosic wastes are used, no pretreatment step will be needed. Essentially, only technology transfer is involved in commercialization of this process, rather than the development of new technology. Our cost analysis, the objective of this present work, projects calcium acetate costs of 0.258

The feasibility of a residue biomass bioconversion process to prepare calcium magnesium acetate deicing salt

US/kg (

Quantifying capture efficiency of gas collection wells with gas tracers.

0.117/lb) for a full-scale plant of 454 metric tons/day (500 U.S. tons/day).