Daily Treatment Capacity Research Articles

Pre-industrial-scale Combined Solar Photo-Fenton and Immobilized Biomass Activated-Sludge Biotreatment

This paper reports on upscaling of a new technology combining solar photo-Fenton and aerobic biological processes to successfully treat a saline industrial wastewater containing around 600 mg L-1 of a non-biodegradable compound (α-methylphenylglycine, MPG) and dissolved organic carbon (DOC) of between 400 and 600 mg L-1. Pilot-plant tests were used in designing this demonstration hybrid solar photocatalytic-biological plant with a 4 m3 daily treatment capacity. It consists of a solar photo-Fenton reactor with 100 m2 of solar compound parabolic collectors (CPCs) and an aerobic biological treatment plant based on an immobilized-biomass activated-sludge reactor (1 m3). The catalyst concentration was Fe2+ = 20 mg L-1. The overall efficiency in the combined system was around 95% mineralization. 50% of the initial DOC was degraded in the photo-Fenton pretreatment, and 45% was removed in the aerobic biological treatment.

Evaluation of PCDD/Fs emission from fluidized bed incinerators co-firing MSW with coal in China

The levels and homologue profile of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) from stack gas of three typical fluidized bed incinerators co-firing municipal solid waste (MSW) with Chinese coal were measured. The PCDD/Fs emission was in the range of 0.0054–0.1961 ng I-TEQ/N m 3. Comparison of PCDD/Fs detection results by HRGC/HRMS and HRGC/LRMS suggested that it was feasible to detect fly ash with high PCDD/Fs concentration by HRGC/LRMS. Several factors on PCDD/Fs emission were discussed. The primary reason for the lower PCDD/Fs emission was the inhibition mechanism of relatively high sulfur in feeding coal on PCDD/Fs formation. The emission results also showed that there was no directly correlation between PCDD/Fs levels and CO, O 2 and HCl concentration in flue gas. It was estimated that about 0.1034 g I-TEQ was annually emitted to atmosphere from the tested three MSW incinerators (total daily treatment capacity is 800 tonnes MSW).

Cold Climate Sequencing Batch Reactor Biological Phosphorus Removal – Results 1991-92

The aeration tank in a small scale wastewater treatment plant was converted to a sequencing batch reactor (SBR) with a maximum volume of approx. 27 m3. The main purpose of this study was to examine low temperature biological phosphorus removal (BPR). The wastewater temperature varied during the study between 3 and 8°C, with a water temperature at or below 5°C during 7 months of the year. The SBR unit has been in operation from the end of 1989, the study period discussed here covered July 1991 - December 1992. SBR cycle time was varied between 6 and 12 hours, giving a total daily treatment capacity of between 18 and 36 m3. The influent biological oxygen demand - 7 days (BOD7) levels varied between 88 and 165 mg/l. Corresponding phosphorus levels were between 3.10 and 9.55 mg/l The mean effluent level of phosphorus was 1.57 mg/l and the BOD7 value was 23 mg/l. This gives a mean total phosphorus reduction of 74% and a BOD7 reduction of 81 %. During the study, mean supernatant suspended solids (SS) levels were quite high, at around 36 mg/l. This high SS level contributed a major part of both outlet phosphorus as well as BOD7 value. Effluent soluble values for phosphorus and BOD7 were 0.79 mg/l and 9 mg/l. The supernatant SS component of BOD7 and phosphorus increased at lower temperatures. It was not possible to reduce or balance this increase by increased cycle time or increased settling time within the maximum cycle time available (12 hours). Stable low supernatant phosphorus and BOD7 levels are thus to a large degree controlled by the effluent SS level. A maximum of 20 mg/l supernatant SS is necessary to reach target supernatant values of less than 1 mg/l of phosphorus and 15 mg/l of BOD7.