（通訊員王攀攀）近日，我校yl7703永利袁巧霞教授課題組在WaterResearch上發表了題為“Performance evaluation of a solar evaporation system for liquid digestate concentration”的研究論文。該研究開發了一套“太陽能-空氣”強化蒸發的沼液濃縮系統，在典型工況下對系統性能進行了評估及環境經濟性評價。研究結果為沼液的低成本、高效濃縮提供了新思路。

近年來，随着我國畜牧業的發展，畜禽糞污的安全處理及資源化利用問題倍受人們關注。厭氧消化是農業廢棄物資源化利用的一種重要技術手段，它可在處理農業廢棄物的同時獲得清潔能源，對緩解能源危機及環境污染治理均具有重要意義。然而，随着畜禽糞污厭氧消化技術的推廣，厭氧發酵沼液的産生量随之增大，沼液的安全消納已成為當前中國農業源廢棄物污染防治必須要面對和解決的問題。

沼液可作為有機肥利用，但養分含量低限制了其消納半徑，以太陽能為熱源進行高溫濃縮，可以提高沼液的養分濃度，但随着濃縮溫度的升高，沼液中遊離氨濃度增加，因蒸發損失的養分量也增大。基于此，本研究開發了一套“太陽能-空氣”強化蒸發的沼液濃縮系統，該系統以太陽能為熱源同時對沼液和空氣進行升溫，利用太陽能調節空氣的載濕能力和沼液的蒸發強度，通過系統工藝和參數的優化強化傳熱傳質，實現沼液的低溫高效濃縮，同時協同沼液的酸調節以控制系統總養分的損失。該系統在日平均太陽輻射為773.08W/m²時，沼液濃縮率可達43.33%。當調節沼液初始pH為5時，沼液中的氮以穩定的離子态铵形式存在，使氨氮回收率由原沼液的6.42%提高到78.39%。研究結果還表明，改變系統中沼液流速，可調控噴淋室内沼液與空氣的熱質交換強度，改善沼液濃縮效果。針對沼液處理規模為100噸/天的沼氣工程，其濃縮成本僅為6.8元/噸，遠低于目前的膜濃縮成本。相較于以化石燃料為能源的蒸發技術，該系統能減少2.40×10⁵噸的CO₂排放，獲得3.48×10⁶美元的碳信用。該研究開發了一套經濟、環保、高效的沼液濃縮技術，為沼液的高值化利用提供條件。

我校yl7703永利博士研究生王攀攀為論文第一作者，yl7703永利袁巧霞教授為論文通訊作者。該研究得到了國家重點研發計劃的資助。

【英文摘要】

The safe and efficient treatment and resource recovery of the large amount of liquid digestate (LD) produced by biogas plants has become an important factor limiting the development of the biogas industry.In this study, a solar evaporationsystem was developed based on low cost, highefficiency, and high nutrient recovery of LD concentration. The effects of different parameters, including solar radiation, LD flowrate, and daily treatment capacity, on the concentration efficiency, nutrient recovery, andthermalefficiency were investigated. Economic andenviroeconomicanalyseswere conducted to comprehensively assess the feasibility and environmental benefits of the systemforlarge-scale biogas plants. The results showed that the higher the solar radiation, the higher the air temperature and its saturation vapor pressure, which led to an increase in the concentration efficiency of LD. The LD concentration efficiency can reach up to 43.33%whenthe average daily solar radiation was773.08 W/m².High solar radiation also contributed to high LD temperature, leading to an increase in the percentage of free ammonia (NH₃)intheLD, which was not conducive to the recovery of ammonia nitrogen (NH₃-N).By increasing the LD flow rate, the heat and mass exchange between air and LD in the spray chamber was enhanced, resulting in higher concentration efficiency.The variation of LD flow rate and daily treatmentcapacityhad little effect on nutrient recovery. The recovery of NH₃-N and soluble salts in the concentrated phase could be as high as 78.39% and 84.19%, respectively, whentheinitial pH of LD was 5, the air flow rate was 0.03 m³/s, and the LD flow rate was 6 L/min. In addition, the economic analysisindicated that theconcentrationcost of the system in treating a daily LD production of 100 tons was1.08 USD/ton. The solar evaporation system can reduce CO₂emissions by 2.40×10⁵tons and earn carbon creditsof3.48×10⁶USD over its lifetime.This study provides a new direction and reference for LD concentration.

論文連接：https://doi.org/10.1016/j.watres.2022.118056

審核人：袁巧霞