If you want to skip all whitespace lines, you should use this test: '   '.isspace(). 
Since you may want to do something more complicated than just printing the non-blank lines to the console(no need to use CSV module for that), here is an example that involves a DictReader:
#!/usr/bin/env python
# Tested with Python 2.7
# I prefer this style of importing - hides the csv module
# in case you do from this_file.py import * inside of __init__.py
import csv as _csv
# Real comments are more complicated ...
def is_comment(line):
    return line.startswith('#')
# Kind of sily wrapper
def is_whitespace(line):
    return line.isspace()
def iter_filtered(in_file, *filters):
    for line in in_file:
        if not any(fltr(line) for fltr in filters):
            yield line
# A dis-advantage of this approach is that it requires storing rows in RAM
# However, the largest CSV files I worked with were all under 100 Mb
def read_and_filter_csv(csv_path, *filters):
    with open(csv_path, 'rb') as fin:
        iter_clean_lines = iter_filtered(fin, *filters)
        reader = _csv.DictReader(iter_clean_lines, delimiter=';')
        return [row for row in reader]
# Stores all processed lines in RAM
def main_v1(csv_path):
    for row in read_and_filter_csv(csv_path, is_comment, is_whitespace):
        print(row)  # Or do something else with it
# Simpler, less refactored version, does not use with
def main_v2(csv_path):
    try:
        fin = open(csv_path, 'rb')
        reader = _csv.DictReader((line for line in fin if not
                                  line.startswith('#') and not line.isspace()),
                                  delimiter=';')
        for row in reader:
            print(row)  # Or do something else with it
    finally:
        fin.close()
if __name__ == '__main__':
    csv_path = "C:\Users\BKA4ABT\Desktop\Test_Specification\RDBI.csv"
    main_v1(csv_path)
    print('\n'*3)
    main_v2(csv_path)
     
    
datavariable. That assignation toempty_linesis incorrect without declaring it first and you have a typo in theforwith an extra closing parentheses.databefore theforloop.csv.readerin Python 2, as mentioned in the docs.def is_empty_line(line): ...for readability, say if you want to skip a line containing all white-space. It can also be a good idea to skip both comments and empty lines - more reason to re-factor into separate functions.