Comprehensive utilization of activated sludge for the preparation of hydrolytic enzymes, polyhydroxyalkanoates, and water-retaining organic fertilizer.
The urban wastewater treatment industry produces a large amount of excess activated sludge which is mainly composed of microbial biomass and costly to be disposed. In this research, a comprehensive utilization of activated sludge was developed by sequentially extracting hydrolytic enzymes and polyhydroxyalkanoates (PHAs), and the residue was used to prepare water-retaining organic fertilizer. The sludge was extracted with fourfold H2O-containing 1% Triton X-100 with the yield of 66.7% protease activity. The enzyme solution was precipitated in 80% acetone and vacuum dried at 40°C at the dried enzyme yield of 2.4 g/kg wet sludge. The enzyme product contains collagenase, lipase, amylase, and cellulase activities, which are good compound enzymes to feed. The PHAs were extracted with 30% sodium hypoclorite:chloroform (1:3). The PHA solution was decolored and dried, and pure white PHAs were obtained at the yield of 70.1 g/kg wet sludge. The residue was used to prepare water-retaining organic fertilizer at the optimal condition. The fertilizer absorbs 131.3-fold distilled water and had good performance in water retention and can effectively slow down the loss of soil moisture when added into soil. This work provides a simple and practical approach for comprehensive utilizing activated sludge with significant economic benefits.
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.
He
H
Ni
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.
Xiao-Min
XM
Fan
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.
Hao-Ning
HN
Guo
b Guangzhou Development Zone Water Purification Plant , Guangzhou , China.
Jian-Hua
JH
Liang
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.
Qing-Rong
QR
Li
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.
Liu
L
Yang
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.|c Guangzhou Huichuan Medical Technology Company, Baiyun District , Guangzhou , China.
Hui
H
Li
a Guangdong Provincial Key Lab of Biotechnology for Plant Development , School of Life Sciences, and Research and Development Center for Rare Animals, South China Normal University , Guangzhou , China.
Hai-Hang
HH
Li
D005308:Fertilizers / Q000032:analysis; D006868:Hydrolysis; D010447:Peptide Hydrolases / Q000737:chemistry / Q000302:isolation & purification*; D054813:Polyhydroxyalkanoates / Q000737:chemistry* / Q000302:isolation & purification; D011108:Polymers / Q000737:chemistry*; D012722:Sewage / Q000382:microbiology*; D014867:Water / Q000737:chemistry
D005308:Fertilizers; D054813:Polyhydroxyalkanoates; D011108:Polymers; D012722:Sewage; D014867:Water; D010447:Peptide Hydrolases
Activated sludge; hydrolytic enzymes; polyhydroxyalkanoates; water-retaining organic fertilizer