Start-up performances of dry anaerobic mesophilic and thermophilic digestions of organic solid wastes.

Two dry anaerobic digestions of organic solid wastes were conducted for 6 weeks in a lab-scale batch experiment for investigating the start-up performances under mesophilic and thermophilic conditions. The enzymatic activities, i.e.

[Effect of limited aeration on the thermophilic anaerobic treatment of high-sulfate refractory wastewater].

A thermophilic up-flow anaerobic sludge blanket (UASB) reactor was used to treat high-sulfate refractory wastewater from a sulfite pulp mill. The microorganisms were inhibited significantly as the result of sulfate reduction. Based on the consideration that the limited aeration may strip hydrogen sulfide out and oxidize part of the sulfide into nontoxic elemental sulfur, limited aeration was introduced into the reactor later to reduce the inhibition.

Effect of limited aeration on the anaerobic treatment of evaporator condensate from a sulfite pulp mill.

Serious inhibition was found in the regular up-flow anaerobic sludge blanket (UASB) reactor in treating the evaporator condensate from a sulfite pulp mill, which contained high strength sulfur compounds. After applying the direct limited aeration in the UASB, the inhibition was alleviated gradually and the activity of the microorganisms was recovered. The COD removal rate increased from 40% to 80% at the organic loading rate of 8kgCODm(-3)d(-1) and a hydraulic retention time of 12h.

Effect of loading rate on the granulation process and granular activity in a bench scale UASB reactor.

The effect of organic loading rate (OLR) on the granulation process was evaluated using upflow anaerobic sludge blanket (UASB) reactors running under different conditions. Results showed that increase of OLR, extracellular polymer (ECP) content and granulation were closely related to one another. ECP in the sludge accumulated over a short period under overloading conditions, which greatly enhanced the granulation process.

Examining farmland applications of composted biosolid wastes depending on nutrient balance in soils.

This study emphasizes nutrient balance of soils in the farmland application of composted biosolid wastes. The loading rates of plant nutrients following the compost application to farmland in Japan were estimated and compared with the nutrient uptake of agricultural plants. Results show that the current compost application in Japan can meet the requirements of agricultural plants for plant nutrient Ca, except for K, Mg, P, Fe, Mn, Cu, and Zn.

A model of fish preference and mortality under hypoxic water in the coastal environment.

Eutrophication and associated occurrence of hypoxic condition could cause significant damage to marine ecosystems, resulting in considerable economic losses to fisheries and aquaculture and is a major source of stress that fish often have to contend with in order to survive. This problem is likely to be exacerbated in the coming years, since the wastewater treatment facilities is unlikely to catch up with increasing human activities. Moreover, large-scale reclamation projects in coastal areas have recently been increased, and these activities certainly have adverse impacts on water quality and fisheries resources.

Simulation of eutrophication and associated occurrence of hypoxic and anoxic condition in a coastal bay in Japan.

A probabilistic method of calculating the occurrence of oxygen-depleted water within a combined hydrothermal and water quality model was presented in this paper to investigate the environmental impact of eutrophication on the living resources. The method was applied to an eutrophicated shallow coastal bay in western Japan, where the occurrence of red tides at the water surface and the onset of bottom hypoxic waters are observed every summer. Both meteorology and freshwater inflow contribute to the development of stratification of the bay, thus limiting the dissolved oxygen supply to bottom waters.