Aerobic Biodegradation of OCDD by P. Mendocina NSYSU: Effectiveness and Gene Inducement Studies.

The goals of this study were to assess the effectiveness of (1) enhancing octachlorinated dibenzo-p-dioxin (OCDD) biodegradation under aerobic conditions by Pseudomonas mendocina NSYSU (P. Mendocina NSYSU) with the addition of lecithin, and (2) inducing OCDD ring-cleavage genes by pentachlorophenol (PCP) and OCDD addition. P. Mendocina NSYSU could biodegrade OCDD via aerobic cometabolism and lecithin was used as a primary substrate. Approximately 74 and 67% of OCDD biodegradation was observed after 60 days of incubation with lecithin and glucose supplement, respectively. Lecithin was also used as the solubilization additive resulting in OCDD solubilization and enhanced bioavailability of OCDD to P. Mendocina NSYSU. Two intradiol and extradiol ring-cleavage dioxygenase genes (Pmen_0474 and Pmen_2526) were identified from gene analyses. Gene concentration was significantly enhanced after the inducement by PCP and OCDD. Higher gene inducement efficiency was obtained using PCP as the inducer, and Pmen_2526 played a more important role in OCDD biodegradation.

Comparison of protease activities in different Bacillus licheniformis strains using wastewater sludge and synthetic soy medium as raw material.

The production of extracellular protease by different Bacillus licheniformis strains (ATCC 21415, ATCC 21417 and ATCC 21424) was tested in wastewater sludge as a raw material as well as in synthetic soy medium to compare the capacity of protease production by different strains and to compare the capacity of the medium to provide nutrients for enzyme synthesis. All of the strains showed similar activities in both media. The protease activity was very high in the fermentor in both of the media compared with the shake flask. Results from microbial selection indicated that ATCC 21424 had high potential for protease production using sludge as a growth medium. The observation from this study suggested that wastewater sludge could be used as a raw material (nutrient source) to produce protease for industrial applications.

Integrated advanced natural wastewater treatment system for small communities.

A study was conducted to evaluate the nutrient removal capability of an existing and successfully operated overland flow and wetland wastewater treatment system following a waste stabilization pond. Seasonal temperature effects on performance were also investigated. The treatment system studied consists of a two-cell waste stabilization pond followed by an overland flow system and a wetland system. The influent and effluent samples were analyzed for BOD5, suspended solids (SS), pH, temperature, ammonia nitrogen, nitrate nitrogen, and total phosphorus. The results of the study indicate that the combined pond, overland flow and wetland system provided excellent treatment of municipal wastewater. The overall average BOD5 removal by the entire treatment system was about 90.0% and the overall average suspended solids removal was about 93.4%. The ammonia nitrogen and total phosphorus removal efficiencies of the entire treatment system were 90.7% and 84.2%, respectively.

Treatment of slaughterhouse wastewater in a sequencing batch reactor: simulation vs experimental studies.

In wastewater treatment, the objective of process optimization is primarily to obtain a good treatment efficiency of a specific pollutant. The operational objective of increased productivity has also to be met. This includes a sufficient reduction in the duration of a batch process through batch scheduling. The aim of this paper is thus to find the best cycles for simultaneous carbon, nitrogen and phosphorus (CNP) removal from slaughterhouse wastewater in a sequencing batch reactor (SBR) using GPS-X software and ASM2d model. Simulations with different aeration strategies, residence time, sludge age and feed strategies were carried out to determine the best system performance. The simulation results showed best performance with a system comprised of two equal feeds operated at 48 h hydraulic retention time (HRT) and 20 d solids retention time (SRT). Simulation also showed that addition of metal salts was necessary to reduce the level of phosphorus (P) to meet the requirement (P<1 mg l(-1)). The addition of acetate was also necessary to complete the denitrification process. The simulated results were compared against the experimental results obtained from laboratory SBR. The simulated results of COD, nitrates/nitrites and ammonia removal were very close to the experimental results. A diference of 2-4% between the simulated COD and the experimental COD was observed and that could be attributed to the error in evaluation of the inert COD. For ammonia removal, the simulated (99.9%) and experimental (93-100%) results were practically identical. However, a notable difference in o-PO4 concentration was observed (38% removal by simulation against 78% removal through experiments). After metallic salts addition, P removal efficiency was 98% or 1% less than that observed through experimental results.

Subsurface-flow constructed wetlands treatment in the plains: five years of experience.

This paper documents the performance of a subsurface-flow constructed wetlands system during its initial five years of operation under variable loading and operating conditions associated with a northern midwestern US climate. The results indicate that effective and sufficient CW seasonal removals of TSS, VSS, CBOD5, COD, and fecal coliform were achieved. Wastewater temperatures seemed to affect CBOD5 and COD removal rates. Nitrogen and phosphorus reductions were not as effective and varied seasonally, as well as with wastewater temperature. The addition of a sand filter, to aid in further nitrification and disinfection following CW treatment, markedly improved the performance of the wetlands system. After a few years of operation, the remarkable performance of the CW system was dampened by apparent clogging and subsequent eruption of wastewater at the head-end of the treatment cells. While clogging was partially caused by biomass build-up in the wetlands substrate, visual observations suggest that excessive vegetation coupled with relaxed maintenance may also be responsible for clogging.