Depuration Plants Research Articles

SCP and crude pectinase production by slurry-state fermentation of lemon pulps

Single cell protein (SCP) and crude pectinolytic enzymes production from citrus pulps is reported. SCP and enzymes were produced by slurry-state flask cultivation of Aspergillus niger and Trichoderma viride on pulps from lemon juice clarification. Production as well as crude pectinase activity was not affected by the high dry matter content of the pulps. Both the protein content in the residue and the enzyme activity in the supernatant were higher in T. viride than in A. niger culture. The crude pectinase of T. viride, whose specific activity was similar to that found for a commercial concentrated preparation, could be utilized in the same citrus processing factory as well as in other factories which use large amounts of pectinolytic crude preparations, for example to enhance depuration plant performance.

Brote epidémico de tularemia en la provincia de Cuenca en relación con la manipulación de cangrejos

To report the clinical and epidemiologic characteristics of 19 patients diagnosed of tularemia at our hospital following an epidemic outbreak occurred in our health area. Retrospective analysis of clinical records of patients admitted to our hospital who were examined at the Infectious Diseases Clinic and had clinical findings and epidemiologic data consistent with tularemia during the period from June 1998 to March 1999. A patient was considered to fulfill the case definition when clinical symptoms, epidemiologic data and the following laboratory criteria were met: antibody titer to Francisella tularensis (tube agglutination test) > or = 1/128 in the convalescence serum specimen, seroconversion or recovery of the microorganism from biological material. Nineteen patients with a median age of 60 years. Males predominated (63.1% male patients); all of them had handled red crayfish from the same source (río Mayor). The incubation period ranged from 0 to 15 days (mean 4.88 days). All patients presented with the ulceroglandular form. Seventy-three percent of patients received doxycycline. Only one patient relapsed. Water samples from the reservoir of the depuration plant of the river were positive to F. tularensis by PCR. This same result was confirmed in stomach and hepatopancreas of crayfish fished in río Mayor in the second half of July. The most likely hypothesis of this outbreak was the contamination of the river water with animals dead from tularemia which, together with the characteristics of the transmission mechanism (wounds caused by crabs) had contributed to the acquisition of this disease in humans. Interestingly too, red crayfish as the source of infection.

Fuzzy Modelling with Input Variables Reduction.

Fuzzy reducing modelling of a dynamical system arising only from an input-output data set is the aim of this work. A modelling method that includes model input reduction is proposed. It starts from Takagi-Sugeno approach and from algorithm EG2, a modified version of the Quinlan ID3 automatic learning algorithm. The proposed method is implemented as a tool in C language, compatible with the Fuzzy Toolbox of MATLAB, and is put to use to the same water depuration plant described by Takagi and Sugeno.

Biodegradation of nonionic surfactants. I. Biotransformation of 4-(1-nonyl)phenol by a Candida maltosa isolate

Results are reported concerning biodegradation of 4-(1-nonyl)phenol by cultures of a Candida maltosa strain isolated from aerobic sludge samples collected at a depuration plant treating wastewaters from a textile industry. The yeast was able to utilize 4-(1-nonyl)phenol as a sole carbon and energy source. Preliminary attempts to draw the actual metabolic pathway evidenced microbial attack on the alkyl chain with the production of 4-acetylphenol. To the best of our knowledge this is the first report describing a microorganism capable of attacking nonylphenol in axenic culture and at the same time allowing for the identification of its degradation products.

Microbial Purification of Shellfish: A Review of Depuration and Relaying

A review of the literature on shellfish depuration and relaying revealed wide diversity in microbial uptake and elimination among shellfish species and for different microorganisms. Information on relaying of five commercial shellfish species and on controlled purification (depuration) of 11 species indicates that such processes are effective in reducing the levels of bioconcentrated bacteria and viruses from shellfish. The degree of bacterial and viral bioconcentration varies with shellfish species; however, the primary sites of bioconcentration are the hepatopancreas and digestive diverticula. Low levels of enteric viruses and coliphage may be sequestered in shellfish hemolymph and tissues, thus protecting them from elimination through depurative processes. Vibrio spp. appear to proliferate when closely associated with intestinal cells of shellfish. Shellfish relaying techniques offer effective microbial depletion provided water quality is acceptable and shellfish remain physiologically active. The current body of literature on controlled purification demonstrates a broad spectrum of conditions under which shellfish are depurated. Optimal times, temperatures and salinities for effective depuration vary among shellfish species. Proper design and operation of depuration plants is crucial to insure process integrity. Recirculating and flow-through purification systems are effective in reducing the levels of pathogenic and indicator microorganisms from shellfish, but the extent to which they reduce viruses from shellfish is uncertain. Studies are needed to validate the effectiveness of depuration processes in eliminating pathogenic viruses and to address the adequacy of indicator bacteria as measures of enteric virus contamination.

Aerobic treatment of wine-distillery wastewaters.

Waste from food-processing and allied industries is largely made up of organic compounds which can be metabolized by aerobic or anaerobic means. However, these wastes present a series of problems to biological depuration plants, such as the need for prior treatment to establish conditions suitable for the development of the microorganisms responsible for the process; and the long retention time of the biomass if acceptable effluents are to be obtained. Again, the seasonal nature of many of these industries makes for very heterogeneous waste. This means that treatment plant must be versatile and are subject to rapid successions of close-down and start-up interspersed with long intervals of inactivity. All these difficulties oblige the industries in the sector to adapt depurative technology to their particular needs. Wine distilleries fall into this general category. Their waste (called vinasses) is acidic, has a high organic content and varies widely according to the raw matter distilled: wine, lies, etc. This paper studies the start-up of digestors for aerobic treatment of vinasses and the establishment of optimum operating conditions for an adequate depurative performance.

An Experimental Depuration Plant: Operation and Evaluation

The operation of a prototype (24-bushel capacity) depuration plant for the bacteriological cleansing of oysters was evaluated under prevailing Gulf Coast environmental conditions. Results indicated that with proper plant location and basic engineering design of the system, commercial depuration of shellfish is a feasible method for purifying oysters harvested from restricted waters. Eight trials were conducted over a 15-month period to cover seasonal changes. The depuration tank design permitted three pallets, each holding 16 baskets of one-half bushel capacity, to be stacked in the tank. A fecal coliform MPN of 130 or less/100 g for depurated oysters was established as the maximum level of acceptability for a 72 hour period of depuration. Physical parameters of the sea water which were measured included salinity, temperature, turbidity, pH, and dissolved oxygen. Determinations of the percent wet/dry weight and percent glycogen of depurated oyster meats revealed no adverse effect on quality.