Study On Reuse Of Sewage Sludge As Growth Media For Ornamental Plants

Increasingly, tons of sewage sludge were disposed to environment annually with more and more waste water treatment plants constructed in China, leading to serious problems to human health. However, sewage sludge which contains rich nutrients for plant is a good source of organic fertilizer after optimized and adjusted composting process, especially using N retention technology. On the other hand, most nurseries in the world have based for many years their growing media on peat. Which are being rapidly depleted, causing environmental concerns that have lead to many individual countries to limit the extent of peat mining, and prices are increasing as a result. Research on peat alternatives is of great interest in the future, and the increasing interest in waste recycling is another cause to advocate the recycling and use of organic wastes and composts as soil or potting amendments; it could be one of the most attractive methods of solving the problem of waste disposal.In this assay, sewage sludge(SS),spent mushroom(SM) and herb residues(H)was mixed for composting, with the purpose of evaluate the good mixture which reduced the loss of N, which prove to be one of most important factors in reusing biosolid composts. After that, peat was partially or totally substituted by the former composts. And the result was as follows:(1) Addition of SM and H raised the temperature faster, and showed a shorter composting maturating time than piles with nothing in them. It also resulted in lower ammonium-N and higher nitrate-N in the compost products. Among the windrows, SM and HR amendment caused a better condition in N circulation than control did, which presented as TN and N losses of treatments were 22.45g/kg-24.99g/kg and 10.2%-22.4% compared to control with 18.66g/kg and 40%,which composted by sewage sludge and sawdust.(2) It was pointed out that the pile with 40%SM added had highest TN and lowest N loss, which proved to be 24.99g/kg and 10.2%.(3) The addition of sewage sludge compost to peat increased plant nutrient and was better for cucumber growth than peat did. (4) The addition of herb residues compost to peat was harmful for the growth of cucumber, however, adding water resistant agent could reduce this detrimental effect.(5) As biosolid recycling is the main objective of the present work, the mixtures S1P3,S4 in trail 1 ,the combination of S4W in trail 3 will be the most convenient substrate to use.