Acute impacts of mixed heavy metals and diclofenac on sludge activity and enzyme activity involving with the biological nitrogen removal

Acute impacts of mixed heavy metals and diclofenac (DCF) on sludge activity and enzyme activity involving with the nitrogen removal were investigated. The synergistic inhibition on sludge activity and enzyme...

Influence of selected antibiotics on respirometric activity of activated sludge

The main topic of this study is to determine the effect of selected antibiotics on the respirometric activity of sewage sludge microorganisms. Within the practical part of the work, several respirometric measurements were performed with activated sludge from a wastewater treatment plant, while the influence of three selected antibiotics — sulfamethoxazole, sulfapyridine, and ciprofloxacin, on sludge activity was monitored. The aim of the work was to point out the inhibitory effect of all monitored compounds on sludge activity and to quantify the inhibitory effect. For sulfamethoxazole (in the concentration range of 0.142—1.42 mg·L−1), the determined inhibition was in the range of 9.67—27.7 %, depending on the concentration of the test substance and the type of respirometric measurements. For sulfapyridine, inhibition values ranged from 1.13 % to 31.9 % for the concentration range from 0.134 to 1.34 mg·L−1. Ciprofloxacin inhibited the activity of activated sludge microorganisms in the range of 4.55 % to 28.8 % (at CPX concentrations from 0.104 to 1.04 mg·L−1).

Removal and Effects of Surfactants in Activated Sludge System

The widespread use of detergents has raised concern with regard to the environmental pollution caused by their active substances, which are biorefractory, toxic or persistent. Even though anionic and non-ionic surfactants often used in commercial detergents composition are reasonably degradable under aerobic conditions and not particularly toxic at low concentrations, high concentration of surfactants influenced the activated sludge activity and are harmful for the aquatic environment. In the literature, data on the biodegradability and/or ecotoxicity of a certain type of surfactant (anionic, nonionic, cationic) are usually presented. Our study aimed to assess the biodegradability of a mixture of two types of surfactants (anionic mixed with non-ionic) and also, effects caused by their presence of elevated concentrations to the activated sludge micro-organisms, within a batch experiment. We performed a biodegradability test (according Zahn-Wellens method) on 2 synthetic solutions with high concentrations of anionic surfactant �methyl dodecylbenzene sulfonate (15-25 mg/L) and non-ionic surfactant -4-nonylphenyl-polyethylene glycol (10 mg/L). The study established different percent of biodegradability (measured by COD decrease and surfactants removal) depending on initial concentrations of anionic and nonionic surfactants in the tested solutions. High surfactants concentrations modulated the activity and morphology of activated sludge, so its degradation efficiency of the organic substrate has decreased. Surfactant solutions resulting from biodegradability experiment have been tested for toxicity to planktonic crustaceans (Daphnia magna).