Advances in Stress Factors of Aquatic Macrophytes in Polluted Water

Aquatic macrophytes are of significant importance for polluted water restoration.This paper reviews current research progress of stress factors for aquatic macrophytes growth and analyzes existing problems. Factors including nutritive salt, suspended sediments and deposited sediments had an obvious effect on aquatic macrophytes growth, and the impacts of light intensity, heavy metals, temperature and pH on the growth of aquatic macrophytes were little than that of the above factors. The problems existed in present researches were: dynamic and quantificational studies of the impacts of some stress factors on aquatic macrophytes growth were insufficient, there was lack of integrated investigations considering several factors which were of complex relationship.

Improving Biogas Production and Biodegradability of Acid Hydrolytic Cotton Stalk with Addition of Nutritive Salts and Complex Anaerobic Cellulose Decomposing Bacteria

Nutritive salts and complex anaerobic cellulose decomposing bacteria (CACDB) were added for anaerobic digestion process in order to improve biogas production and biodegradability of acid hydrolytic cotton stalk. The results showed that addition of CACDB, nutritive salt I and nutritive salt II could effectively enhance daily biogas production, cumulative biogas and methane yields, in this treatment, the total gas production, daily average gas production, TS gas production rate, VS gas production rate and average yield of methane were all highest and reached 5908.90 mL, 196.96 ± 7.97 mL·d-1, 143.07 ± 5.79 mL·g-1, 156.32 ± 6.33 mL·g-1, 102.58 ± 3.34 mL·d-1, separately. The addition of CACDB and nutritive salts could improve the biodegradability of acid hydrolytic cotton stalk, in all addition treatments, the degradation rates of cellulose and lignin, VS reduction rates were higher and C/N ratios were lower than control treatment. The SEM analysis showed that the microstructure changes of digestion residues were helpful for biogas production.