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Polydimethylsiloxane (PDMS) is widely used in industrial products, medical and health care products, and personal care products. In the treatment process of sewage, PDMS can be hardly biodegraded but enter the environment mainly through the discharge of excess sludge, and only a small amount of PDMS adsorbed on the suspended solids or sludge particle surface is discharged into water body and sediment with treated sewage. There is no enough evidence to verify that PDMS can vertically migrate in sediment. The degradation of PDMS in sediment is very slow, but PDMS can be degraded in different types of soils. PDMS has less risk to aquatic ecosystem, and no apparent acute toxicity to benthos. In soil environment, PDMS and its degradation products have no significant effects on the soil microorganisms, soil animals, and crops. Though a few studies indicated that PDMS and its degradation products have relatively low ecological toxicity in various environments, it is still very important to clarify the potential threat of PDMS to the environment because of the increasingly large number of PDMS being produced and used. [ABSTRACT FROM AUTHOR]

Activated sludge process is widely used in treating a wide variety of wastewater, but the by-product is the large amount of excess sludge. To treat the excess sludge properly could spend 25%-60% of the total cost of wastewater treatment, while improperly treating the sludge could cause serious secondary pollution. Therefore, the reduction of excess sludge is becoming a rising challenge. Using thermophiles to degrade excess sludge is a way easy in operation and inexpensive in maintenance, being a promising method in application. This paper reviewed the recent progress in the researches of sludge-degrading thermophiles, their working mechanisms, and the enzymes from thermophiles, such as thermophilic proteolytic enzymes and thermophilic lipases which play an important role in the degradation of sludge. The factors affecting the degradation of sludge by thermophiles were summarized, and the perspectives for the further research on the application of thermophiles in digesting sludge were discussed. [ABSTRACT FROM AUTHOR]

In conventional wastewater bio-treatment, little attention has been paid on the bio-degradation of grease, causing low efficiency in the process, and thereby, further study should be made on the development and application of related mature and effective bio-treatment techniques. This paper summarized the pathways and mechanisms of grease bio-degradation in wastewater treatment, with the focus on the research progress in the functional microbes involved in lipid hydrolysis and long-chain fatty acid degradation, and briefly introduced a series of new treatment technologies based on the habitat differences of the functional microbes. The key breakthrough directions in the technological study of grease bio-degradation were prospected, expecting to provide theoretical guidance to the development of the related technologies. [ABSTRACT FROM AUTHOR]

There are plenty of methods used for the assessment of organic compounds biodegradability, but lack of comprehensive literatures in systematically introducing the assessment methods and guiding the choice of the methods. This paper briefly introduced the indicative parameters in assessing organic compounds biodegradability and the assessment methods of aerobic and anaerobic biodegradation, with the focus on the principles and criteria in the choice of the assessment methods, and analyzed in detail the reasons for the differences in the biodegradation rates of organic compounds when different test methods were adopted. Taking the standards established by the Organization for Economic Co-operation and Development (OECD) as an example, the process of choosing and applying the assessment methods was introduced, the systematic method-choosing route was integrated, and the advantages of the OECD standard methods were pointed out.

Polydimethylsiloxane (PDMS) is widely used in industrial products, medical and health care products, and personal care products. In the treatment process of sewage, PDMS can be hardly biodegraded but enter the environment mainly through the discharge of excess sludge, and only a small amount of PDMS adsorbed on the suspended solids or sludge particle surface is discharged into water body and sediment with treated sewage. There is no enough evidence to verify that PDMS can vertically migrate in sediment. The degradation of PDMS in sediment is very slow, but PDMS can be degraded in different types of soils. PDMS has less risk to aquatic ecosystem, and no apparent acute toxicity to benthos. In soil environment, PDMS and its degradation products have no significant effects on the soil microorganisms, soil animals, and crops. Though a few studies indicated that PDMS and its degradation products have relatively low ecological toxicity in various environments, it is still very important to clarify the potential threat of PDMS to the environment because of the increasingly large number of PDMS being produced and used.

Activated sludge process is widely used in treating a wide variety of wastewater, but the by-product is the large amount of excess sludge. To treat the excess sludge properly could spend 25%-60% of the total cost of wastewater treatment, while improperly treating the sludge could cause serious secondary pollution. Therefore, the reduction of excess sludge is becoming a rising challenge. Using thermophiles to degrade excess sludge is a way easy in operation and inexpensive in maintenance, being a promising method in application. This paper reviewed the recent progress in the researches of sludge-degrading thermophiles, their working mechanisms, and the enzymes from thermophiles, such as thermophilic proteolytic enzymes and thermophilic lipases which play an important role in the degradation of sludge. The factors affecting the degradation of sludge by thermophiles were summarized, and the perspectives for the further research on the application of thermophiles in digesting sludge were discussed.

In conventional wastewater bio-treatment, little attention has been paid on the bio-degradation of grease, causing low efficiency in the process, and thereby, further study should be made on the development and application of related mature and effective bio-treatment techniques. This paper summarized the pathways and mechanisms of grease bio-degradation in wastewater treatment, with the focus on the research progress in the functional microbes involved in lipid hydrolysis and long-chain fatty acid degradation, and briefly introduced a series of new treatment technologies based on the habitat differences of the functional microbes. The key breakthrough directions in the technological study of grease bio-degradation were prospected, expecting to provide theoretical guidance to the development of the related technologies.