The sludge treatment process with three stages: application of bio-floc and wolffia (Lemna minor) for sludgewater from bronze featherback ponds, exploiting sludge for microbial-compost (MC) production and evaluating effects of MC on leaf-eating vegetable cultivating on alluvial soil of Vi Thanh city, Hau Giang province. The results showed that total of suspended soild (TSS) and chemical oxygen demand (COD) in sludge-water reduced strongly, especially COD decreased in the bio-floc treatment
total of Kjeldahl nitrogen (TKN) and total of phosphorus (TP) in water reduced in the wolffia treatment
two kg sludge plus eight kg rice-straw with Trichodenna sp. fungus was optimal ratio for compost production after that supplemented with beneficial bacteria liquid (with two strains of nitrogen-fixing bacteria and phosphate-solubilizing bacteria) into compost and incubated in 7 days to MC with characteristics as follows: neutral pH
C/N ratio, available P and exchageable K were average concentration
population of beneficial bacteria were over 107 CFU/g, Coliforms and SamoneUa did not detect in MC. Evaluation effects of MC on leaf-eating vegetable cultivation, showed that biomass yield of 1 ton/ha MC plus 50 percent chemical fertilizer NPK treatment did not differ from biomass yield of 100 percent chemical fertilizer NPK treatment but nitrate concentrations in vegetable were lower than nitrate levels in vegetable only applying chemical fertilizer and saved 50 percent inorganic fertilizer level but soil fertility of MC treatment did not change in comparison to initial.