ros-gra

I was looking for a microbiology forum but this may work, 'cause the work is focused on environmental science. First, a bit of context, in our current job we are collecting water samples from a river and the purpose is to sequence all the microbiome. So, aside from membrane filtering or centrifugation, which other methods (avoiding damage to the DNA) can we use to concentrate the microorganisms from this kind of sample? For example, I was wondering if I can agglutinate them?