Effects of oxytetracycline and zinc ion on nutrient removal and biomass production via microalgal culturing in anaerobic digester effluent.

Removal of nutrients from swine wastewater digester effluent (SWDE) by microalgae Coelastrella sp. and production of Coelastrella sp. were investigated at the presence of oxytetracycline (OTC) and Zn(II). Mechanisms of stress of OTC and Zn(II) on microalgae were discussed via analyzing the removal performance of SWDE and biochemical characteristics of microalgae. Results showed that removal efficiency of ammonia nitrogen and biomass yield of microalgae at the presence of 5000 µg/L of OTC decreased by 13.1% - 50.1% and 28.2% -71.5%, respectively, when Zn concentration was increased from 0.50 mg/L to 5.0 mg/L. The presence of 5.0 mg/L Zn(II) promoted the accumulation of lipids in microalgae, and the presence of 50 µg/L OTC increased unsaturation of fatty acid methyl ester. Content of glutathione and activity of both glutamine synthetase and superoxide dismutase decreased with the increase of OTC concentration, while content of adenosine triphosphatase increased when Zn(II) concentration was also increased.

Use of potassium dihydrogen phosphate and sawdust as adsorbents of ammoniacal nitrogen in aerobic composting process.

Three kinds of adsorbents-potassium dihydrogen phosphate, sawdust and mixture of potassium dihydrogen phosphate and sawdust were added respectively into composting to investigate their adsorption effect on ammonia. The experimental results showed that all the adsorbents could restrain ammonia volatilizing, with the sorption of potassium dihydrogen phosphate adsorbents being the best of all, the sorption of mixture adsorbent with potassium dihydrogen phosphate and sawdust being the second and the sorption of sawdust adsorbent being the last. Therefore, the total nitrogen loss ratios respectively reduced from 38% to 13%, 15% and 21% after adding these three kinds of adsorbents into composting. However, potassium dihydrogen phosphate produced negative influence on composting properties as its supplemented amount exceeded a quantity basis equivalent to 18% of total nitrogen in the composting, for example: pH value had been lessened, microorganism activity reduced, which finally resulted in the reduction of biodegradation ratio of organic matter. But it did not result in these problems when using the mixture of potassium dihydrogen phosphate and sawdust as adsorbent, in which the amount of potassium dihydrogen phosphate was under a quantity basis equivalent to 6% of total nitrogen in the composting. Moreover, the mixture adsorbent produced better adsorption effect on ammonia, and raised biodegradation ratio of organic matter from 26% to 33%.