
Dioxin Emission Factors for the Incineration of Different Medical Waste Types
Previous research works showed that to protect public health, hospital incinerators should be provided with equipment to reduce atmospheric emissions. Most hospital incinerators do not possess such equipment, so efficient methodologies should be developed to evaluate the safety of incineration procedures. Emission factors can be used for an easy estimation of the parameters defined in legislation. Nevertheless, the actual knowledge is very scarce, mainly because previously published emission factors do not include enough information about the incinerated waste types and the respective proportion in incinerated mixture. The existence of different waste classifications also reduces the usefulness of previously published results. This study reports the first dioxin emission factors estimated for the incineration of medical waste, segregated in different types according to the classification of the Portuguese legislation. The main purpose was to evaluate the influence of waste type on emission factors, assessing how useful they are if not associated to the composition of the incinerated mixture. The study also allowed analyzing the correspondence between different waste classifications that are being used, comparing the estimated emission factors with the sole results previously published for specific waste types but segregated according to a different classification. The influence of the incinerated waste type and segregation practices on the concentration and amount of emitted dioxin was assessed, as well as the influence of segregation practices on the amount of wastes that must be incinerated. To estimate eventual hazards for human health, dioxin concentrations in combustion gas flow were compared with the respective legal limits.
Concentration of Atmospheric Pollutants in the Gaseous Emissions of Medical Waste Incinerators
ABSTRACT The purpose of this paper is to quantify the production of medical waste from a general hospital and to evaluate the atmospheric pollutant concentrations in gaseous emissions associated with its incineration. A 3.8 kg (bed.day)-1 production of medical waste was estimated for 1998; its incineration is related with an ash production of 0.3-0.4 kg (bed.day)-1. The concentrations of atmospheric pollutants were estimated using emission factors, comparing the effluents with and without control of atmospheric pollutants. The calculated concentrations were compared with the emission limits established by Portuguese legislation. The results indicate that, if there is no control of atmospheric pollutants, their concentrations exceed the established limits. This is observed even if correct operation and maintenance procedures are used. The emission concentrations of dioxins are higher than the Portuguese emission limit, which is particularly worrying due to the high toxicity of some of these compounds. Generally, it is possible to reduce pollutant concentrations if appropriate control equipment is used. The conclusions obtained clearly justify the great concern regarding air pollution associated with medical waste incinerators currently operating in Portugal.
Chemical-Looping Combustion of Biomass in a 10 kWth Reactor with Iron Oxide As an Oxygen Carrier
Chemical-looping combustion of biomass was carried out in a 10 kWth reactor with iron oxide as an oxygen carrier. A total 30 h of test was achieved with the same batch of iron oxide oxygen carrier. The effect of the fuel reactor temperature on gas composition of the fuel reactor and the air reactor, the proportion of biomass carbon reacting in the fuel reactor, and the conversion of biomass carbon to CO2 in the fuel reactor was experimentally investigated. The results showed that the CO production from biomass gasification with CO2 was more temperature dependent than the CO oxidation with iron oxide in the fuel reactor, and an increase in the fuel reactor temperature produced a higher increase for the CO production from biomass gasification than for the oxidation of CO by iron oxide. Although the conversion of biomass carbon to CO2 in the fuel reactor decreased with the increase of the fuel reactor temperature, there was a substantial increase in the proportion of biomass carbon reacting in the fuel react...