https://users.ugent.be/~evolcke/pdf/2012_Daelman_WaterRes_MethaneEmissionsFromMunicipalWWtreatment.pdf

Methane emission during municipal wastewater treatment.

Anaerobic digestion often generates ‘biogas’ – an approximately 3:1 mixture of methane and carbon dioxide – which has been known to be a ‘clean’ fuel since the late 19th century. But a great resurgence of interest in biogas capture – hence methane capture – has occurred in recent years due to the rapidly growing spectre of global warming. Anthropogenic causes which directly or indirectly release methane into the atmosphere, are responsible for as much as a third of the overall additional global warming that is occurring at present. Hence the dual advantage of methane capture – generating energy while controlling global warming – have come to the fore. This paper presents an overview of the natural and the anthropogenic sources that contribute methane to the atmosphere. In this context it underscores the urgency with which the world must develop and enforce methods and practices to enhance methane capture.

Anaerobic digestion for global warming control and energy generation—An overview

In the present study, the bioaccumulation of heavy metals (Cr, Cu, Cd, Pb) content were determined in freshwater edible fishes Cyprinus carpio Linnaeus and Pelteobagrus fluvidraco, which were caught from the Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that the Cr, Cu, Cd and Pb content in the edible parts of the two fish species were much lower than Chinese Food Health Criterion (1994). However, the results showed marked differences in the four analyzed metal content between the two species and different tissues as well as significant variations. Pb content were the highest in the liver of fishes, Cd contents were almost the same in all organs of fishes, Cr contents mainly enriched in the kidney and liver, Cu contents were the highest in gills, However, the total metal bioaccumulation were greatest in the liver, gills and the lowest in the muscle. Although the total accumulations were highest in P. fluvidraco compare then C.carpio. This investigation indicated that fish products in Meiliang Bay, Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Pb. Further, this is the first report on seasonal distribution of heavy metals and proximate compositions of commercialized important edible fishes from Meiliang Bay, Taihu Lake, China.

Bioaccumulation of heavy metals in fish species from the Meiliang Bay, Taihu Lake, China

https://espace.library.uq.edu.au/view/UQ:407004/UQ407004_OA.pdf

Seasonal investigation of heavy metals in marine fishes captured from the Bay of Bengal and the implications for human health risk assessment

bioaccumulation of heavy metals in fish species from the meiliang bay taihu lake china

Methane emissions from a full-scale A/A/O wastewater treatment plant

Metal accumulation in fish is a global public health concern, because the consumption of contaminated fish accounts for the primary exposure of humans to toxic metals. In this study, the concentrations of arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) in Crucian carp (Carassius auratus),Yellow catfish (Pelteobagrus fulvidraco), and Bighead carp (Hypophthalmichthys nobilis) from Nansi Lake of China were evaluated, and compared with the corresponding historical values in 2001 when the government started to govern water environment effectively. Bioaccumulation of heavy metal was highest in P.fulvidraco, followed by C.auratus and H.nobilis. The concentrations of Pb, As, Cd were much lower than the historical values, but Hg concentration was higher, suggesting that heavy metal pollution problem in fish from Nansi Lake still exists. Health hazard assessment showed no health risk from exposure to Pb, As, Cd, and Hg by consuming fish from this lake.

Heavy Metal Bioaccumulation and Health Hazard Assessment for Three Fish Species from Nansi Lake, China

Nitrous oxide (N2O) emissions from a typical full-scale tertiary municipal wastewater treatment plant (WWTP) in northern China were investigated during spring and summer of 2010. Results showed that the major emission sources of N2O performed the following descending order: oxic tanks, final clarifier tanks, anoxic tanks, sludge concentration tanks and anaerobic tanks. The total annual N2O flux from the oxic tanks was the highest and accounted for the majority of total N2O emissions of this WWTP. The emission factors derived from the field measurements included per capita emissions of 1.73–2.19 g of N2O person–1 y–1 and flow based emissions of 2.37×10–5–3.01×10–5 g of N2O (L of wastewater) –1. The N2O emissions accounted for approximately 0.10%–0.13% of the total nitrogen removed in this WWTP. The most significant factors influencing N2O emissions in this plant were dissolved oxygen concentration and nitrite concentration in the oxic tanks.

Nitrous oxide emissions from a typical northern Chinese municipal wastewater treatment plant

Direct emissions of N2O, CO2, and CH4, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26–39 to 112–173 g CO2-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N2O, CO2, and CH4) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO2-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems.

Yangang Ren

Papers

Methane emissions from a full-scale A/A/O wastewater treatment plant

Heavy Metal Bioaccumulation and Health Hazard Assessment for Three Fish Species from Nansi Lake, China

Nitrous oxide emissions from a typical northern Chinese municipal wastewater treatment plant

Direct emissions of N2O, CO2, and CH4 from A/A/O bioreactor systems: impact of influent C/N ratio