What is this white stuff on my face after microneedling? (Photo)

this is your acne breaking out. you need much more than microneedling I suggest seeing an acne and acne scarring expert.  
For facial rejuvenation I would suggest a combination approach of :

1) skin care with products and PRP/microneedling
2) PDT light therapy few times a month with growth factors
3) laser treatments like clear and brilliant regularly and a few times a year Fraxel, Viva, Co2/Erbium
4) Sculptra injections a few times a year for collagen production with fillers like juvederm/restylane/belotero/radiesse/bellafill
5) thermage/ultherapy for yearly skin tightening with or without PDO or cone based instalift threads for lifting
6) botox every 2-3 months to stop movement lines and prevent lines at restBest, Dr. Emer.

it is never easy to make an assessment just from a picture, but in your particular case with active acne in my experience it is absolutely contraindicated to perform microneedling Because of risk of infection and inflammation. My advise is to wait for your acne to heal and than get evaluated by an experienced physician in microneedling .

Thank you for your question!  If the person is being particularly aggressive, then this will be increased. It is possible that the tears are causing swelling and micro scarring. This will heal, but it is not ideal for the skin to go through this level of trauma and can result in a waxy look to the skin.  I would seek out a center that does micro needling with a motorized pen. The pen will efficiently puncture the skin at a 90 degree angle and not tear the skin. The pen can also be set at the right depth for the different areas of the face (as your thickness is different throughout). This allows for a very precise mechanical injury that is quickly and easily repaired with little inflammation resulting in a real dewey youthful and smooth look to the skin.  Best of luck!