/ About 130 sites across the state now use treated sludge as fertilizer. As damaging algae blooms continue to afflict Florida, the state is taking steps to crack down on and track pollution from biosolids, the waste from sewage plants loaded with nutrients that can fuel blooms. But the new rules, conservationists warn, continue to ignore a loophole for about 40% of the state’s waste. WLRN is committed to providing South Florida with trusted news and information. As the pandemic continues, our mission is as vital as ever. Your support makes it possible. Please donate today. Thank you. At a final hearing last week, state environmental regulators said the new rules address two classes of sludge largely used in agriculture. Class AA, a third class, gets more highly treated to remove pathogens and heavy metals and is classified as a fertilizer not covered by the rules.