Ke koho ʻana i kahi mea hoʻomaʻemaʻe wai ma lalo o ka wai, aia kekahi mau ʻāpana e noʻonoʻo ai:

1. **Ke ʻano o ka mea hoʻomaʻemaʻe wai:**
- Aia kekahi mau ʻano like me ka Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF), a me Reverse Osmosis (RO). Ke koho ʻana, e noʻonoʻo i ka ʻenehana kānana, ka pono kānana, ka maʻalahi o ka hoʻololi ʻana i ka pahu pahu, ke ola, a me ke kumu kūʻai.

2. **Microfiltration (MF):**
- ʻO ka pololei o ka kānana ʻana mai ka 0.1 a i ka 50 microns. Aia nā ʻano maʻamau i nā pahu kānana PP, nā pahu kānana kalapona i hoʻāla ʻia, a me nā pahu kānana seramika. Hoʻohana ʻia no ka kānana koʻikoʻi, e wehe ana i nā ʻāpana nui e like me ka sediment a me ka ʻōpala.

- ʻO nā hemahema ka hiki ʻole ke wehe i nā mea ʻino e like me ka bacteria, hiki ʻole ke hoʻomaʻemaʻe i nā pahu kānana (hoʻopau pinepine ʻia), a pono ke hoʻololi pinepine.

3. **Ultrafiltration (UF):**
- Hoʻopili pololei ka kānana mai 0.001 a i 0.1 microns. Hoʻohana i ka ʻenehana hoʻokaʻawale membrane ʻokoʻa e hoʻoneʻe i ka ʻōpala, sediment, colloids, bacteria, a me nā molekole organik nui.

- Loaʻa nā pōmaikaʻi i ka nui o ka hoʻihoʻi ʻana i ka wai, ka hoʻomaʻemaʻe maʻalahi a me ka holoi ʻana i hope, ke ola lōʻihi, a me ke kumu kūʻai haʻahaʻa.

4. **Nanofiltration (NF):**
- Aia ka pololei kānana ma waena o UF a me RO. Pono ka uila a me ke kaomi no ka ʻenehana hoʻokaʻawale membrane. Hiki ke hoʻoneʻe i nā ion calcium a me ka magnesium akā ʻaʻole hiki ke hoʻopau loa i kekahi mau iona ʻino.

- ʻO nā mea pōʻino ʻo ia ka haʻahaʻa o ka hoʻihoʻi ʻana i ka wai a me ka hiki ʻole ke kānana i kekahi mau mea ʻino.

5. **Reverse Osmosis (RO):**
- ʻO ka pololei kānana kiʻekiʻe loa ma kahi o 0.0001 microns. Hiki ke kānana i nā mea haumia a pau e like me ka bacteria, nā maʻi maʻi, nā metala kaumaha, a me nā lāʻau antibiotic.

- Loaʻa nā pōmaikaʻi i ka helu desalination kiʻekiʻe, ka ikaika mechanical kiʻekiʻe, ke ola lōʻihi, a me ka hoʻomanawanui i nā hopena kemika a me ke olaola.

Ma nā ʻōlelo o ka hiki ke kānana, ʻo ka helu maʻamau ʻo Microfiltration> Ultrafiltration> Nanofiltration> Reverse Osmosis. ʻO nā Ultrafiltration a me Reverse Osmosis nā koho kūpono e pili ana i nā makemake. He mea maʻalahi ka Ultrafiltration a haʻahaʻa ke kumu kūʻai akā ʻaʻole hiki ke hoʻopau pololei ʻia. He mea maʻalahi ka Reverse Osmosis no nā pono wai kiʻekiʻe, e like me ka hana ʻana i ke kī a i ʻole ke kope, akā makemake paha i nā hana hou no ka ʻai ʻana. Manaʻo ʻia e koho e like me kāu mau koi a me kou makemake.