Study on Migration and Transformation Rule of Organic Pollutants (COD) in Aerated Zone

Collecting waste water with a certain c onc entration of organic pollutants COD (chemical oxygen demand), static adsorption, static biodegradation and dynamic soil column experiments were made in laborato ry, we researched migration and transformation of COD in aerated zone, and put f orward a mathematical model showing the process. The results show that adsorptio n of organism in aerated zone is linear, which is represented by Henry's law s =K dc+s d, adsorption coefficient K d=0.069 3; biodegradati on diagram accord basically with first order kinetics equation c=c 0e -K 1t , biodegradation coefficient K 1 = 0.049 9 d -1 ; dispersio n coefficient D= 0.002 42 m 2/d in experiments. The migration and transform ation of organic pollutants (COD) in aerated zone jointly result from many f actors such as dispersion, adsorption and biodegradation etc..

Moisture Movement and Transformation Law under Soil Moisture Conserving Irrigation in Winter Wheat Field

[Objective] The aim was to provide theoretical basis for field moisture conserving irrigation.[Method] With Xiaoyan No.6 as tested material,three different kinds of mulching irrigation treatments were carried out （straw mulching;plastic mulching;PAM control adjustment mulching）.With non-mulching treatment as control,moisture conserving effect of different treatments were compared.[Result] The results showed that the water consumption of winter wheat under different soil moisture conservation treatments was low at earlier stage and later stage,but high at mid-stage,which was consistent with the water consumption law of control.There were some differences in terms of consumption intensity because of irrigation schedule and growth condition;soil moisture conservation treatments could restrain ineffective evaporation of soil moisture before anthesis.We also found that the variation of soil moisture at depth of 0-20 cm in PAM and control treatment was dramatic.The soil moisture of the former was lower than the latter at the depth of 0-20 cm,but higher at the depth of 20-50 cm.The difference of soil moisture at the depth of 0-50 cm was significant.[Conclusion] Plastic mulching and straw mulching could restrain evaporation effectively.

Pharmaceuticals and personal care products transference-transformation in aquifer system

Pharmaceuticals and personal care products(PPCPs)are a new kind of contaminant widely existing in the surface water and groundwater environment.In recent years,PPCPs have been received widely attention from many researchers.The migration and transformation of PPCPs are mainly photolysis,biodegradation,adsorption and hydrolysis in aquifer environment.The influencing factors of PPCPs migration include PPCPs’own physical and chemical properties,types and contents of organic matter,pH,lithology,geotechnical structure and the thickness of vadose zone,etc.At present,the research of PPCPs in China is still in the primary stage,especially on the contaminant in aquifer system.Therefore,the research in this field needs to be further strengthened.

Transformation and migration of phosphorus in excess sludge reduction pretreatment by alkaline ferrate oxidation combined with anaerobic digestion

Recently,more and more attention has been paid to the strong oxidation ability of newly prepared potassium ferrate(NAPF) in sludge reduction process,but less attention has been paid to the change of phosphorus in this process.The feasibility of phosphorus migration and transformation during excess sludge reduction pretre atment using NAPF pre-oxidation combined with anaerobic digestion was investigated.After 70 mg/g suspended solids NAPF pretreatment and 16 days anaerobic digestion,the solid-phase volatile suspended solids decreased by 44.2%,and much organic matter had been released into the liquid-phase and then degraded during digestion by indigenous microorganisms.As the sludge pre-oxidation process was performed,solid-phase organic phosphorus and chemically combined phosphorus also released into the liquid-phase as PO4^3-,peaking at 100 mg/L.During anaerobic digestion,the Fe3+in the liquid-phase was gradually reduced to Fe2+,and then formed Fe^2+-PO4^3- compound crystals and re-migrated to the solid-phase.The concentration of PO4^3- decreased to 17.08± 1.1 mg/L in the liquid-phase after anaerobic digestion.Finally,the phosphorus in the Fe^2+-PO4^3- compound accounts for 80% of the total phosphorus in the solid-phase.A large number of vivianite crystals in sludge were observed.Therefore,this technology not only effectively reduces sludge,but also increases the proportion of PO43-in the sludge in the form of Vivianite.

Effects and fate of metal-based engineered nanomaterials in soil ecosystem:A review

Metal-based engineered nanomaterials(MENMs)are increasingly being used in people’s working lives.Although MENMs have important effects on soil ecosystem and play an important role in solving soil environmental problems,the hazards associated with MENMs cannot be ignored.Therefore,more and more scholars have studied the behavior and effects of nanomaterials in soils in recent years.In this review,we explore the articles on MENMs and soil ecosystem retrieved from various databases from 2013 to 2022.We discuss the mechanisms of MENM toxicity,the current state of soil ecosystem,the ecological effects of MENMs on soil microbes,earthworms,and plants,and the ways by which soil organisms take up MENMs.We now know that although MENMs have positive effects on soil ecosystem,their potential hazards are not negligible.Therefore,it is necessary to investigate the effects of MENMs on soil organisms.Meanwhile,we should pay more attention to the negative effects of MENMs on soil ecosystem while exploring their positive effects on soil ecosystem in future research.