MTech Thesis: Sorption of Hexavalent Chromium by Iron Impregnated calcined Bauxite by Krishnadas P.

The adsorption of hexavalent chromium (Cr(VI)) onto calcined bauxite modified with ferrous iron and ferric iron was investigated. Parameter optimization was conducted for both the adsorbents and a comparative analysis of their efficiency was performed under the same conditions. The optimum operating conditions for ferrous modified calcined bauxite (FEMCB) was found to be 3 g/L adsorbent dose and 60 minutes equilibrium time. pH and temperature had no significant impact on the removal efficiency. At optimum conditions, a removal efficiency of >99% was obtained. Ferric modified calcined bauxite (FRMCB) performed best (>99%) at 4 g/L adsorbent dose with an equilibrium time of 90 minutes. The optimum pH and temperature were observed as 5±0.2 and 30 ^OC. Freundlich isotherm fitted well for the adsorption of Cr(VI) using ferrous modified calcined bauxite while for adsorption with ferric modified calcined bauxite, better fit was obtained for Langmuir isotherm. FEMCB followed pseudo-second order kinetic model and pseudo-first order kinetic model fitted well for FRMCB. Iron leaching was observed in the effluent after adsorption with FEMCB. 

            The application of FRMCB as an adsorbent for Cr(VI) from real mine drainage was investigated and it showed good removal upto 98%. Optimized operational conditions were 2 g/L adsorbent dose for 120 minutes at pH 4 and 30 ^OC. The reaction fitted well to Langmuir isotherm and first order reversible kinetic model. The effluent was free from iron leaching.

            Fixed bed column study was performed using FRMCB for treating synthetic Cr(VI) wastewater with varying bed depths, flow rates and initial concentrations. The column study was carried out for real wastewater treatment also and a reduction in column efficiency was observed may be due to the interference of other ions and high pH. The column data was fitted to Bohart-Adams model and resulting parameters were calculated. 

Krishnadas P.

Assistant Engineer

LSGD Section

Kalliassery/Narath GP

M Tech Thesis -ANNIE K S

INTEGRATED - TWO STAGE ANAEROBIC DIGESTION FOR THE RECOVERY OF ENERGY FROM KITCHEN REFUSE

SYNOPSIS

In India there is a good sunshine for about 300 days in a year which encourages anaerobic digestion. Kitchen refuse and other similar garbage present a big disposal problem like bad odor, insects and rodents causing very dangerous diseases. The kitchen refuse from canteens, hostels, big hotels and similar garbage sources can be effectively used for anaerobic digestion to recover the fuel energy as well as good manure from exhausted slurry. The aim of the present study is to evaluate bio gas production from kitchen refuse using different seeding materials like cow dung and digested sludge of septic tank and an attempt has been made to work out the cost that could be benefited from the probable bio gas production using kitchen refuse. The two phase anaerobic digester bio gas plant of 20 liters capacity of each phase was operated at room temperature, using kitchen refuse of Thrissur Government Engineering College Canteen as feed stock material. The maximum bio gas produced was found to be as 0.301m³/kg VS added/day, at the rate of loading of 3.3kgVS/m³ slurry/day when digested sludge of septic tank is used as seeding material.

SUMMARY AND CONCLUSION

Ø GENERAL

From the experiment it was seen that the bio gas plant using kitchen refuse from Thrissur Government Engineering College canteen, gave a maximum bio gas volume of 0.301m³/kg VS added/day at the rate of loading of 3.3kg/VS/m³ digested slurry/day with digested sludge of septic tank as seeding material. Since the experiment was carried out in a summer season in the temperature range of 27-32⁰C, the temperature would not affect appreciably for gas yield.

                       

                        As the plant was operated at room temperature, and got a biogas volume of 0.301m³/kg VS added/day, it is clear that if the temperature, stirring and uniform feeding are constantly maintained, the biomethanation  can be increased to 1.009m³/kg VS added/day.

Ø THE FEASIBILITY OF BIOGAS PLANT

It is also seen that the biogas plant is viable and economical if it is operated on large scale rather than small scale (i.e., for all hostel blocks of Government Engineering College, Thrissur).

Ø ENERGY RECOVERY AND ITS INTEGRATED USE

The exhausted slurry has good fertility value and this manure could be used for good yield of vegetables which in turn used for cooking in kitchen, which gives the kitchen refuse material as “feed stock” for digesters. So this is an integrated scheme of utilizing the waste material for energy recovery in an environmental friendly way.

Ø RECOMMENDATIONS FOR FURTHER DEVELOPMENT AND STUDIES

The following recommendations are suggested for further development and for future studies.

1.   The digesters can be installed below the ground level for good temperature maintenance.

2.   A room may be constructed with “Green house effect” using solar energy for good temperature maintenance.

3.   Proper mixing arrangement, using motor pump sets or circulating the same biogas with pressure.

4.   Uniform feeding avoiding feast or fast conditions of microorganisms.

5.   Buffering of pH arrangements, especially for winter months to avoid souring of digester by much accumulation of volatile acids.

6.   The arrangements for bio gas cleaning (removing moisture) and utilising the bio gas within 10m of production source for proper pressure and without leakage.

7.   A cylindrical shape or egg shape digester will have lesser scum forming are. Hence it is suggested to design egg or cylindrical shaped digester.

8.   As far as possible, the plug flow condition should be maintained and also proper retention time should be given for digestion to be fully completed.

9.   The exhausted slurry can be dried on sand bed and mixed with other organic fractions of plant origin for aerobic composting to be used as manure.

10. The water requirements for the digester slurry can be met with by using waste water from Hostel blocks. The sewage or sullage water can be used for this purpose in the place of tap water.

ANNIE K S  ASSISTANT ENGINEER, LSGD SECTION, VAZHAYOOR, MALAPPURAM.

A STUDY ON THE STRENGTH AND COMPRESSIBILITY BEHAVIOUR OF ORGANIC CLAYS FROM KUTTANAD, KERALA

 

ABSTRACT: This paper presents the study on the strength and compressibility behaviour of soil samples collected from Thakazhy, Thayankary, Kandamkary, and Champakulam villages belonging to Kuttanad taluk in Kerala. The influence of organic matter on the strength and compressibility behaviour is also presented. The compression indices and the liquid limit of soils increased with increase in organic content. Also, the influences of various pore fluids like water, NaCl, CaCl₂ and FeCl₃. 6H₂O solutions of different concentrations on the index and strength properties are presented. Regression equations for compression index based on simple parameters obtained in the laboratory are developed.

Following were the conclusion of the study.

The natural water content of undisturbed soil samples collected from Thakazhy, Thayankary, Kandamkary, and Champakulam vary from 23 % to 50% with organic content varying from 1.25% to about 7.66%. The soil samples from all the places except Thakazhy fall in the USCS classification of clay with high compressibility, and that from Thakazhy being clay with low compressibility due to the higher percentage sand content in the soil collected from Thakazhy.

Consistency limits tests conducted on modified soils from Thakazhy, Thayankary, Kandamkary and Champakulam, whose organic content has been varied by the addition of starch solutions, indicate that there is an increase in the liquid limit and plasticity index, while plastic limit and shrinkage limit decrease with increase in % organic content.    Consolidation tests on these modified soils indicate that with increasing % organic content the compression index was found to increase.

When different concentrations of NaCl, CaCl₂ and FeCl₃.6H₂O solutions were used as the pore fluid in oven dried soil samples, the liquid limit of all the samples show a decreasing trend as the pore fluid concentration increased. At higher concentrations the diffused double layer is suppressed causing decrease in liquid limit. The liquid limits of oven dried samples amended with organic content show an increasing trend whereas the plastic limits and shrinkage limits were found to be decreased.

The UCC strength of the oven dried samples mixed with NaCl, CaCl₂ and FeCl₃.6H₂O solutions increased marginally and then decreased with the increase in their respective concentrations.

Regression analysis of results for compression index and other basic soil parameters for undisturbed soil samples from the four locations gave way to a new empirical relationship between compression index and initial void ratio which suited the results in the best possible way.

INDUSTRIAL WASTEWATER TREATMENT BY ELECTROCOAGULATION- Resmi P S

ABSTRACT

          Industries are the one among the major consumers of water. Wastewater from industries should comply the wastewater standards. Inadequate treatment of the effluent may result in the release of polluted wastewater to natural water bodies which cause surface and ground water pollution. But the technical advancements make it possible to treat the industrial wastewater to a good quality so that it can be discharged or reused safely.

Electro coagulation utilizes direct current to cause sacrificial electrode ions to remove undesirable contaminants either by chemical reaction and precipitation or by causing colloidal materials and then be removed by electrocoagulation. The electro coagulation system has been found to be effective in treating wastewaters such as paper pulp mill waste, metal plating, tanneries, canning factories, steel mill effluent, slaughter houses, chromate, lead and mercury laden effluents, as well as domestic sewage. These wastewaters will be reduced to clear, clean, odorless and reusable water.

The present study investigated the effectiveness of the electro-coagulation in treating latex wastewater. The influence of electrocoagulation time, voltage, pH, current density, initial metal ion concentration and conductivity on removal performance was explored. The results showed that metal removal increased with increasing current density, electrocoagulation time and conductivity. The results indicated that electrocoagulation with aluminium electrode was very efficient and was able to achieve heavy metal removal. Results obtained with latex wastewater revealed that the most effective removal capacity was obtained at pH 7, current density 135 A/m2, conductivity 13.2 mS/cm. When industrial wastewater was treated at optimized conditions removal was obtained as Zn 87.45% Cu 90.12%, Pb 94% Cr 92.5% in 35 min. The method was found to be highly efficient and relatively fast compared to conventional existing techniques.

BY
RESMI P S
ASSISTANT ENGINEER
LSGD SECTION 
KARAKULAM G P
THIRUVANANTHAPURAM

Thumboormuzy- Pradeesh PB

Any one know Thumoormuzy solid waste management?

Thesis :TREATMENT OF HERBAL PHARMACEUTICAL WASTEWATER AND ITS TOXICITY EVALUATION ON FRESHWATER PRAWNS -Rekha Chandran

aBSTRACt

Herbal pharmaceuticals have gained enough popularity in recent times due to their minimal effects, low cost, safety, efficacy and cultural acceptability compared to allopathic medicines. Being herbal in nature, the effluent from the herbal pharmaceutical industry was not considered as toxic. But the wastewater generated from these industries has high COD and BOD and are toxic due to the presence of many plant alkaloids, organic solvents, alcohol etc. Hence they cannot be discharged into the water bodies without proper treatment.

The effect of using algae, Azolla filiculoides in treatment of herbal pharmaceutical wastewater was studied. The factors which affect the treatment efficiency such as dosage of algae, pH, treatment period and concentration of wastewater were optimized. The algal treated wastewater was further subjected to a secondary treatment using a filtration unit.  The effluent after algal treatment and that after secondary treatment were subjected to bio-assay test using freshwater prawns, Macrobrachium rosenbergii. The results were analysed using Trimmed Spearman Karber method to determine the LC₅₀ values.

The algal treatment is efficient in reducing BOD, COD, chlorides, sulphates, phosphates and nitrate content and turbidity removal. But the toxicity analysis reveals that further secondary treatment is required to remove the toxicity of the wastewater. The effluent from the filtration unit showed positive results in toxicity analysis indicating that it is an efficient method for removal of toxicity of herbal pharmaceutical wastewater.

MTECH Thesis-INVESTIGATION ON WATER QUALITY STATUS IN AND AROUND MADIWALA LAKE AND ESTIMATION OF CONTAMINANT TRANSPORT PARAMETERS-Shruthy

ABSTRACT

           Water  quality is fundamental to the health, efficiency and well being of individuals and societies in all countries of the world. It is threatened by almost all modern interactions of man with nature .Surface water and ground water is related in the hydrologic cycle. The sediments of the rivers are the repositories of toxic wastes, which result in long term effect through mobilization of pollutant and release of nutrients from bottom mud. Urbanization in watershed in turn reduces water that sustains the g/w system -“recharge”. Water supplies from groundwater sources are becoming increasingly important, but they are threatened by unplanned exploitation and by contamination from many sources. The best way to minimize g/w contamination is to prevent it. The regulation of waste disposal to protect groundwater is especially important. Understanding the behavior of contaminants in the subsurface is essential - for effective regulation of potential sources of contamination and for predicting the environmental impact. 

             

Methodology Adopted

Field investigation on Bangalore Madiwala lake water and surrounding groundwater quality was conducted.

The major ion chemistry of groundwater of Madiwala lake premises has been discussed.

The chemical parameters obtained were used for regression analysis for upstream and downstream.

Water quality indices were calculated for the upstream and downstream points.

To study the transport of contaminants in the subsurface an experimental unit was designed with Nitrate and Chloride as tracers.

The mechanics of flow of the influents in soil columns were studied to determine the effective diffusion coefficients.

Visual Solute Transport (VST) software was used for the prediction of solute concentrations over time or distance.