After grounding, polarization charges and shallow charges will be released. The space charges still existing in water tree are called residual charge.

接地放电后，极化电荷及表层电荷释放，仍存在水树枝内的空间电荷即为残留电荷；

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Greenco Environmental collects the residual food from places like the Hyatt and blends that with wood and yard "waste" from tree companies, landscapers and municipalities.

CNN: Downtown Atlanta recycles self into a Zero Waste Zone