Treatment of Domestic Sewage Using Algal Bioreactor

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FINAL REPORT

MTP - Part 2

Domestic Sewage Treatment using Algal Bioreactor[pic 5]

SUBMITTED BY

Shashank Karnawat (2011BB50037)

Supervisor

Dr Ziauddin Shaikh Ahammad

Department of Biochemical Engineering and Biotechnology

Indian Institute of Technology - Delhi

New Delhi – 110016

CONTENTS

1. Introduction and Motivation                        

2. Objective        

3. Literature Review and Project Pre-requisites

        3.1 Design Requirements for the photo-bioreactor system

        3.2 Key Variables of the Process

4. Work Done So Far

        4.1 Protocol of Algal Growth

        4.2 Concentration of Algal Solution

        4.3 Measurement of VSS of sludge and Algal Solution

        4.4 Design of the Reactors

5. Experimentation and Procedure

        5.1 Determining Ammonical Nitrogen

        5.2 Determining Nitrate Nitrogen

        5.3 Determining COD

        5.4 Determining Phosphate

6. Results and Discussion

7. Future Plan of Action

8. References

Domestic Sewage Treatment using algal bioreactor

1. INTRODUCTION AND MOTIVATION FOR THE PROJECT:

With the phenomenal increase in urban population and industrial growth, some of the major problems of a basic nature confronting mankind are those of quality and quantity of food, drinking water, disposal of sewage, industrial wastes, CO2 / other toxic emissions and fuel shortages. Algal bioreactors using suitably controlled algal growth can provide potential solutions to some of these sustainability issues.

This nutrient pollution caused by excess accumulation of nitrogen, phosphorus, heavy metals and other pollutants leads to eutrophication of water. Free ammonia in the water can cause harm to aquatic life and since it consumes oxygen it can lead to oxygen depletion. Nitrate ion in the water can combine with the haemoglobin and act as a potential hazard to infants.

Biological processes are usually more sustainable since they operate at normal temperatures and pressure although usually slow. They are natural and do not require the use of any chemicals. Instead of having a process to remove just P or just N, the biological process can remove both P and N whilst simultaneously sequestering C, reducing other trace nutrients and providing oxygen for improved BOD reduction through an algae/bacteria co-symbiotic relationship. Microscopic algae could be used for nutrient removal through controlled, accelerated eutrophication as a tertiary treatment process.

The main aim of this project will be to replace the existing methods of waste water treatment like the expensive Activated Sludge Process (ASP) which incurs huge pumping costs. Also, big tanks are required for the ASP which result in low light penetration. This all results in overall high energy requirements of the process which will be dealt through novel designs of algal bioreactors which will overcome these shortcomings.

Algae have already been shown to be successful at growing in a range of different stages of a smaller wastewater treatment process.

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1. OBJECTIVES:

• The primary objective of the process is to treat domestic sewage using algal bioreactor focusing on the usage of LED lights and optical fibers for illumination of the bioreactor and hence obtaining a reduction in the energy requirements of the process and an increased algal growth rate.
• Also, the secondary objective will be to achieve the highest possible amount of nutrient reduction possible.

1. LITERATURE REVIEW AND PROJECT-PRE REQUISITES:

This project will study the environmental parameters required to optimize this waste-algae energy process by considering algal growth rate as a function of light, temperature, biomass concentration, nutrient concentration, CO2 and pH.

A set of experiments will be run to test the P, N and C removal capabilities and growth rate of algae under varying light conditions. Various measure will be taken to reduce the overall cost of the process by experimenting with different light sources and shape of reactors which provide the best growth conditions for algae.

3.1 Design requirements for the photo-bioreactor system:

A bioreactor is to support a biologically active culture. Its type is defined by its mode of operation, they can be batch or continuous flow. Bioreactor design is a complex engineering task but under these engineered optimum conditions the microorganisms or cells are able to perform their desired function with greater efficiency.

Quantitative assessment of the bioreactor's environmental conditions (CO2, nutrient concentration, flow rates, lighting, temperature and pH) need to be monitored, reported and controlled to allow comparisons.

The system should be such that there is a minimization of costs like the fixed costs comprising of the capital investment and the running costs which include maintenance and operational costs. The system should also be such that there is a significant reduction in other costs obtained from economic and environmental restrictions whilst optimizing potential to achieve acceptable standards for the treated effluent and reach maximum algal yields.

3.1.1 Summary of design requirements:

• To Remove P and N from wastewater using algae.