Stability of an anaerobic single reactor filled with dolomitic limestone with increased organic load of sugarcane (original) (raw)
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Revista Ceres, 2018
Cassava processing wastewater has a low Volatile Acidity/Total Alkalinity ratio, low buffering capacity and became quickly acidified. In this trial, dolomitic limestone was used as an alkalizing agent in an anaerobic reactor to treat cassava starch wastewater. The dolomitic limestone contained 27% CaO and 23% MgO and granulometry between 24.5 and 38.1 mm. The average Chemical Oxygen Demand of the wastewater was 13331.30 mgO2 L-1, the organic loading rates (OLR) ranged from 1.23 to 16.43 gCOD L-1 d-1 and the hydraulic retention times ranged from 10.00 to 0.80 days. The results showed that the calcium concentrations increased in the reactor effluent and the magnesium concentrations decreased as the organic loading rates increased. Ca2+ and Mg2+ concentrations were approximately 5,000 and 5.05 times greater in the sludge than in the inoculum, respectively. The average pH, Total alcalinity, Volatile Acidity and Volatile Acidity/ Total alcalinity values were 6.69, 882.54 mgCaCO3 L-1, 221...
Industrial Wastewater Treatment Improvements Using Limestone
Journal of Environmental Studies and Researches
T he discharge limits of industrial wastewater effluents are subjected to regulations which are getting more restricted with time. A previous research was carried out in Port Said city, studied the efficiency of treating industrial wastewater using the first stage A-stage of the multiple-stage plant AB-system. From the results of this research, the effluent treated wastewater has high rates of total dissolved solids TDS and chemical oxygen demand COD. The purpose of this paper is to improve the treatment process in removing TDS and COD. A pilot plant was constructed at wastewater pump station in the industrial area in the south of Port Said city. Experimental work was divided into several runs, by adding powdered limestone with different dosages to wastewater. Furthermore, for each run wastewater was filtered after being mixed with limestone powder. TSS and pH as physical variables were also studied. Significant removals of TDS and COD were observed in these experiments showing that using effective adsorbents can aid such removals to large extent.
Enhancement of Limestone Defluoridation of Water by Acetic and Citric Acids in Fixed Bed Reactor
Clean-soil Air Water, 2010
Limestone defluoridation by fixed bed reactor has been studied with water pre-acidified with edible organic acids, viz. acetic acid (AA) and citric acid (CA). The study has been carried out by varying acid concentration, contact time (t), number of repeated use of the same limestone bed (n), and chip size of the crushed limestone using fixed fluoride concentration of 10 mg/L in distilled water and groundwater amended to that concentration of fluoride. The presence of both the acids considerably improved the fluoride removal and the removal increased with increase in the acid concentration. Fluoride removal to less than 0.5 and 1.0 mg/L from initial 5 and 10 mg/L, respectively, have been achieved by the method on treatment with single reactor. The mechanism of fluoride removal in the process thought to be the increase in Ca 2þ activity by dissolution of limestone, which precipitates as CaF 2 . XPS analysis reveals that adsorption also contribute to the fluoride removal along with precipitation. The final pH of water remained within acceptable range for drinking water. Initial concentration of fluoride, effects the removal ability of the limestone particles only to some extent. The influence of other anions on fluoride removal process has a little influence which follows the order phosphate > sulfate > bromide > chloride > nitrate.
Ciência Rural, 2017
ABSTRACT: The main problem in anaerobic digestion of low-protein residues is the instability caused acidity. The use of limestone at the same time as a neutralizing agent and support material is innovative because stones wear allows the slow release of the calcium carbonate thereby eliminating dispersers. Free calcium content in the system was measured in two plug flow reactors filled with vinasse at initial pH of 4.50. The proportion of 1.8 tonnes of limestone per m³ of vinasse was evaluated at the Hydraulic Retention Times (HRT) of 24, 48, 72, 96 and 120 hours, allowing stabilisation at 96 hours. The ratio of Volatile Acids/Total Alkalinity (VA/TA) ranged from 0.2 to 0.4 and the pH reached 7.0, at the HRT of 120 hours. Increasing the HRT also increased the volatile total solids (VTS) and fixed total solids (TFS) in a similar profile to the measured free calcium content, but calcium remained at the appropriate level of 100 to 250mg l-1. The proportion of limestone/vinasse was adequ...
Nutrient removal in an A2O-MBR reactor with sludge reduction
In the present study, an advanced sewage treatment process has been developed by incorporating excess sludge reduction and phosphorous recovery in an A2O-MBR process. The A2O-MBR reactor was operated at a flux of 17 LMH over a period of 210 days. The designed flux was increased stepwise over a period of two weeks. The reactor was operated at two different MLSS range. Thermo chemical digestion of sludge was carried out at a fixed pH (11) and temperature (75°C) for 25% COD solubilisation. The released phosphorous was recovered by precipitation process and the organics was sent back to anoxic tank. The sludge digestion did not have any impact on COD and TP removal efficiency of the reactor. During the 210 days of reactor operation, the MBR maintained relatively constant transmembrane pressure. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn't detoriated the treated water quality.
Lab-scale study of passive treatment to treat acidic mine effluent by using limestone and dolomite
6TH INTERNATIONAL CONFERENCE ON ENVIRONMENT (ICENV2018): Empowering Environment and Sustainable Engineering Nexus Through Green Technology, 2019
Limestone and dolomite were used to treat acidic mine effluent in a lab scale study of a passive treatment. This study focused on improving pH level and reducing heavy metals concentrations of the mine effluent. Both limestone and dolomite with aggregate sizes of 10-20 mm and 30-50 mm were packed in a 40 L tank filled with acidic mine effluent. The mine effluent was sampled from an active iron ore mine in Bukit Besi, Terengganu. The experiments were lasted for 10 days and the mine effluent samples were collected to measure pH, alkalinity and heavy metal concentrations at various retention time. Experimental results revealed that the limestone had shown a better performance compared to the dolomite in increasing pH and reducing metals concentrations of the mine effluent. Most heavy metals were able to be reduced successfully with only manganese (Mn) had shown a poor reduction.
SOME STUDIES ON THE STATUS OF WATER QUALITY IN AN ABANDONED OPENCAST LIMESTONE & DOLOMITE QUARRY
: The present paper summarizes the outcome of preliminary investigations carried out for assessing water quality parameters in an abandoned opencast limestone and dolomite quarry. From the experimental results it was observed that the overall water quality of the water was good and some of the parameters like turbidity (23-32 NTU) and calcium (98-102 mg/L) and magnesium hardness (54-61 mg/L) were slightly greater than the prescribed statutory limits. It can be used for various end uses with minor treatment.