1. Ua ntej ua kom huv txheej npoo ntawm cov hlau hose, thiab tswj kom zoo;
2. Qhov thib ob yog tias txheej saum npoo tsim nyog, thiab tag nrho cov txheej txheem no tuaj yeem tso cov kav hlau hlau ntawm lub cev qhuav dej. Tus nqi pH ntawm lub cev qhuav dej yog zoo dua hauv 13, thiab lub sijhawm tsis pub tsawg tshaj ib nrab ib teev. Ntxuav nrog dej txias tom qab tshem tawm.
3. Tom ntej tuaj yeem nqa tawm, pH ntawm cov kua qaub ua kua qaub yog 3, thiab lub sijhawm daws teeb meem tsis zoo nyob rau kaum feeb, thiab cov kua qaub tau ntxuav tom qab ntxuav;
4. Kev kho mob dub: lub pas dej ua ke concentration tus nqi pH 2-4, kev daws teeb meem yog kaum feeb, thiab nws tsis tshua huv tom qab dub;
5. Thaum kawg nqa tawm cua qhuav, roj;
Raws li lub ntsiab lus thib 5, koj tuaj yeem nqa tawm kev kho xim dub ntawm lub raj cua sov tseem yog txoj hauv kev tsim nyog.