Research on structural characteristics of large-scale CdS thin films deposited by CBD under low ammonia condition

Cadmium sulfide(Cd S) buffer layers with the scale of 10 cm×10 cm are deposited by chemical bath deposition(CBD) with different temperatures and thiourea concentrations under low ammonia condition.There are obvious hexagonal phases and cubic phases in Cd S thin films under the conditions of low temperature and high thiourea concentration.The main reason is that the heterogeneous reaction is dominant for homogeneous reaction.At low temperature,Cd S thin films with good uniformity and high transmittance are deposited by adjusting the thiourea concentration,and there is almost no precipitation in reaction solution.In addition,the low temperature is desired in assembly line.The transmittance and the band gap of Cd S thin films are above 80% and about 2.4 e V,respectively.These films are suitable for the buffer layers of large-scale Cu(In,Ga)Se2(CIGS) solar cells.

Use of additive and pretreatment to control odors in municipal kitchen waste during aerobic composting

The effects of adding a bulking agent and chemically pretreating municipal kitchen waste before aerobic composting were studied using a laboratory-scale system. The system used20-L reactors and each test lasted 28 days. The objective was to decrease NH3 and H2S emissions during composting. The bulking agent, dry cornstalks, was mixed with the kitchen waste to give a mixture containing 15%（wet weight） bulking agent. A combined treatment was also conducted, in which kitchen waste mixed with the bulking agent was pretreated with ferric chloride（FeC l3）. Less leachate was produced by the composted kitchen waste mixed with bulking agent than by the kitchen waste alone, when the materials had reached the required maturity. The presence of cornstalks also caused less H2 S to be emitted, but had little impact on the amount of NH3 emitted. The FeC l3 was found to act as an effective chemical flocculant,and its presence significantly decreased the amounts of NH3 and H2S emitted. Kitchen waste mixed with cornstalks and treated with FeC l3 emitted 42% less NH3 and 76% less H2 S during composting than did pure kitchen waste.

A full-scale integrated-bioreactor with two zones treating odours from sludge thickening tank and dewatering house： performance and microbial characteristics

A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H,S and NH3 were 1.6-38.6 mg.m-3 and 0.1 6.7 mg.m-3 respectively, while the steady-state outlet concentrations were reduced to 0-2.8mg.m - for H2S and 0-0.5mg.m for NH3. BothH2SandNH3 were eliminated effectively by the integrated-bioreactor. The removal efficiencies of H2S and NH3 differed between the two zones. Four species of microorganisms related to the degradation of H2S and NH3 were isolated. The characteristics and distributions of the microbes in the bioreactor depended on the inlet concentration of substrates and the micro-environmental conditions in the individual zones. Product analysis indicated that most of the H2S was oxidized into sulfate in the immobilized zone but was dissolved into the liquid phase in the suspended zone. A large amount of NH3 was converted into nitrate and nitrite by nitration in the suspended zone, whereas only a small amount of NH3 was transferred to the aqueous phase mainly by absorption or chemical neutralization in the immobilized zone. Different microbial populations dominated the individual zones, and the major biodegradation products varied accordingly.