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Effect of particle size and sodium ion concentration on anaerobic thermophilic food waste digestion.

Serial basic tests were conducted for the determination of fundamental kinetics and for the actual application of kinetic parameters to food waste digestion with precise measurement of methane production. The effects of food particle size and sodium ion concentration on the anaerobic thermophilic food waste digestion process were investigated. Results of serial tests for the determination of fundamental kinetic coefficients showed the value of k (maximum substrate utilization rate coefficient) and KS (half-saturation coefficient) as 0.24 hr-1 and 700 mg/L, respectively, for non-inhibiting organic loading range. The substrate inhibition coefficient (Ki) was 1000 mg/L for inhibiting organic loading range. No inhibition effect was shown until 5 g/L of sodium ion concentration was applied to the serum bottle reactor. However, the volume of methane gas was decreased gradually to the concentrations of more than 5 g/L of sodium ion applied. All sizes of food waste particle had the same constants (A: 0.45) but the maximum substrate utilization rate constant (kHA) was inversely proportional to particle size. As average particle size increased from 1.02 mm to 2.14 mm, kHA decreased from 0.0033 hr-1 to 0.0015 hr-1. Result reveals that particle size is one of the most important factors in anaerobic food waste digestion.

Bacteria, Anaerobic↗

[Degradation of plant waste by Coprinus truncorum using 2 culture methods].

Degradation of yard wastes by Coprinus truncorum growing in a vertical aereated bioreactor or in flasks was studied. There was a constant decay of reducing sugars in the medium that avoided their accumulation and their possible repression of degradative enzymes. Endoxylanase activity at first showed a similar pattern in both culture conditions, with maximal activity on the 12th day, but flasks maintained a high activity thereafter. Flasks also showed a higher endoglucanase activity with a peak on the 18th day, whereas the maximal value in the bioreactor was reached on the 26th day. No Mn-peroxidase and only low values of laccase activity were found. The measurements of pH and soluble proteins during the incubation period were suitable indicators of the degradation process by C. truncorum.

Biodegradation, Environmental↗

Analysis of ingredient and heating value of municipal solid waste.

Great differences between municipal solid wastes (MSW) produced at different places and different times in terms of such parameters as physical ingredient and heating value lead to difficulty in effective handling of MSW. In this paper, ingredient, heating value and their temporal varying trends of typical MSW in Beijing were continuously measured and analyzed. With consideration of the process in pyrolysis and incineration, correlation between physical ingredients and heating values was induced, favorable for evaluation of heating value needed in handling of MSW from simple analysis of physical ingredients of it.

China↗

A study of the litter loadings in urban drainage systems--methodology and objectives.

The recently completed report on "The removal of urban litter from stormwater conduits and streams" (by Armitage et al.) notes that little data is available on the nature and quantity of litter that finds its way into the stormwater drainage systems. The Council for Scientific and Industrial Research (CSIR) estimated in 1991 that 780,000 tonnes of waste a year was entering the drainage systems of South Africa, representing a potential removal cost in excess of two billion rand. There is thus a considerable need for finding ways to reduce litter loadings through better catchment management. Although suggestions have been made as to how this might be achieved, there is very little scientifically verified data from anywhere in the world to show that any of these proposed methods would be effective in South Africa. Only through an improved knowledge of the litter loadings in South African urban drainage systems can appropriate strategies to reduce litter loadings be arrived at. This improved knowledge is one of the twin objectives of the Water Research Commission Project No. K5/1051 entitled "The reduction of urban litter in drainage systems through integrated catchment management." Under this project a three-year monitoring programme has been instituted in nine catchments covering a range of different land uses, socio-economic levels and densities in the Cape Metropolitan Area. This paper focuses on the methodology behind the monitoring programme and the objectives it is hoped to achieve.

Cities↗

Catch basin inserts to reduce pollution from stormwater.

Stormwater contamination represents the largest source of contaminants to many receiving waters in the United States, such as Santa Monica Bay in Los Angeles, California. Point sources to these same waters generally receive secondary or better treatment before they are released, and they are usually discharged through outfalls that diffuse the wastewater plume to prevent it from contacting the shoreline. Stormwaters receive no treatment and reach the receiving waters through a variety of ways, but most enter through catch basins or inserts to storm drains that terminate at the beach or in shallow coastal areas. Under these conditions, the stormwater discharge may have greater impact on the quality and utility of the receiving water than the treated wastewater discharges. One method of reducing pollution is to equip catch basins with an insert that can capture pollutants. A number of commercially available devices exist but few have been evaluated by independent parties in full-scale applications. A series of tests using bench and full-scale devices under both laboratory and field conditions were conducted to evaluate their ability to remove trash and debris, suspended solids and oil and grease in stormwaters. The results presented in the paper should provide a basis for future insert development and application.

Cities↗

The influence of experimental conditions on the assessment of the toxicity of 2,4-dichlorophenol to anaerobic degradative bacteria.

The toxicity of 2,4-dichlorophenol (2,4-DCP) to anaerobic bacteria in refuse cultures was investigated at two temperatures (30 and 37 degrees C) and after two different exposure periods to the toxicants. It was shown that at 0.52mM 2,4-DCP the time of exposure of microorganisms to 2,4-DCP affected the relative activity (Av) of the production of methane. Av values at the beginning of the steady-state phase were lower than those recorded two weeks later. The incubation temperature selected also critically affected the assessment of anaerobic toxicity; at 37 degrees C an imbalance of the activities of fermentative bacteria and acetogens with those of methanogens was observed.

Anthelmintics↗

Household sanitation in Uasin Gishu district in Kenya.

In rural Uasin Gishu District in 1990, 78.2% of the households had pit latrines, 11.3% ventilated improved pit latrines, 0.8% water-borne and 9.7% with no toilet facilities. On inspection, 97% of the toilet facilities were in use. Compost pits were present in 52.3% of the households. Utensil drying racks were found in 56.0% of the households. Compared to previous estimates, these levels represent a tremendous improvement in sanitation service coverage. It is recommended that the impact of water and sanitation programmes on health status needs to be evaluated. There is a need for studies to be done on the value of utensil drying racks in disease control.

Garbage↗